Category Archives: Research

Interview with Digital FilmMaker Magazine

I was recently interviewed for one of my favourite magazines – Digital FilmMaker! Here is the original with some of my photos from my ‘A Lion’s Tale’ shoot in Kenya; exactly a year ago. Hope you enjoy it and feel inspired to do your own!

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  1. Why will this project be of interest to readers of Digital FilmMaker?

Hopefully this will be of interest to anyone wanting to shoot their first short film and have only just begun to delve into this creative, thrilling world of visual storytelling. Also, that it is indeed possible to do on a very small budget, whilst travelling to amazing places in the process! Natural history differs to drama in that you cannot predict what the wildlife ‘characters’ will do; or control a great deal of external environmental factors. However, with careful planning and preparation during the pre-production stage; it is possible to make an emotive and personal human-wildlife story that resonates with your target audience.

  1. What had you done project wise in the lead up to this?

This was one of the first and biggest project that I was completely involved in. I studied Zoology during my undergraduate years and played around with cameras in different university societies; but nothing on this scale. I lived in southern Spain all my life before moving to the UK to study as an 18-year old, and upon graduating I then came to Bristol to pursue an MA in Wildlife Filmmaking at the University of West England. I’ve known for a long time that I wanted to get into filmmaking (since I was 12), growing up watching David Attenborough and living in the countryside greatly inspired me. However, there was no academic support in Spain for me to progress in this field, and so dreamed of getting into camerawork and research at the BBC Natural History Unit in Bristol; where a staggering 40% of the world’s wildlife documentaries are made. The Master’s course certainly helped me achieve this, and part of the MA involved making our own film, drawing upon all the skills we learned alongside it. Whilst my academic background was scientific, I had always loved being creative as a child; storyboarding, drawing and writing took me to the far-flung exotic and biodiverse places I saw on our television.

Screen Shot 2017-04-27 at 21.58.46Where I grew up in Southern Spain – the light and birdlife greatly inspired me.

Watching producers and cameramen/women filming behind the scenes sparked my interest; combining the best of both science and art worlds. Then when I was 13 my father bought me my first DSLR, and could finally capture the Bee-eater birds and Short-toed eagles that were always tantalizingly out of reach. Armed with my telephoto lens, I wanted to share my passion with others but knew that being self-taught wouldn’t be enough to cut it in this competitive industry.

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I therefore had a lot of catching up to do at University; joining the Leeds Student Radio societies, television and photography clubs so that I could begin to create a portfolio and apply for the MA. This included a conservation YouTube Channel about local biodiversity, and two radio programs that I produced; Weekly Wildlife Watch and the Travel Talk Show. Whilst radio and LSTV taught me how to write, shoot and focus on story; PhotoSoc helped me to compose and learn about the fundamental principles of photography.

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  1. Who has done what on the film?

As part of the MA requirement, I saw the entire project throughout each of the processes – from the initial idea as a researcher, producer/director, camerawoman, sound, editor, SFX/mixer, grader and now social media manager promoting the content online. It was certainly challenging juggling the different roles, but I loved learning and trying out a variety of methods, techniques and styles from both the drama and natural history world. Learning through mistakes is certainly the best way forward in all walks of life, and by having total creative and editorial control I feel I’ve made something close to my childhood memory and dream. It certainly has been an extraordinary experience that I will remember forever.

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  1. And how did that utilise your individual skills?

With my camerawork, I attempted to adapt different styles of shooting as well as techniques to create a visual story that would suite a film festival audience. Such immersive filmmaking techniques include those seen on various BBC series capture the animal’s perspective to add an emotional level to the story, leading to a more powerful, captivating documentary. I attempted to capture privileged views of the lion in its environment, and learned a great deal about how different documentaries are made by analyzing the shots in different sequences.

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I shot in high speed in attempt to create a sense of drama for the first and last sequence of A Lion’s Tale, as well as with the use of extreme close ups (in particular the ranger patrol) for an immersive feel. The storyboarding of key sequences proved to be invaluable during the shoot, as it allowed me to focus on what I wanted to achieve in terms of framing, direction, action, speed.

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Early morning starts – shooting high speed with the FS700 and Canon 100-400mm.

Equally, I took the camera off the tripod and onto a small inexpensive rig to allow for camera movement – and emphasizes the feeling and mood for a scene. The use of jibs, cranes and float cams are increasingly being used in natural history to create dynamic movement and a parallax between the scenes as seen in drama. The development of gimbals has now made this possible, although I had to resort to a very crude version of one in the end – my arms!

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  1. So what’s the film about?

The Born Free story began with lions, and now 50 years later since the original film, A Lion’s Tale looks at the legacy that actress turn conservationist Virginia McKenna has left and the conflicts that lions and all wildlife face in Kenya. Set in the original heartland of the true father of lions, we journey to Meru National Park to see the Born Free team and Kenya wildlife service rangers on the front line of conflict and education. The world’s largest ivory burn is about to take place, as a symbol of Kenya’s determination to help all wildlife and stop the illegal trade. Will the next generation take up the challenge? Is there hope?

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This film reveals how Kenya’s new generation of conservationists is looking out for all wildlife, including the elephants, which is witnessed at the world’s largest ivory burn event – a symbol of stopping all wildlife trade and helping humans and nature co-exist. Gaining access to this historical event was one of the greatest challenges and provided me with the opportunity to capture a unique moment in time. It has quickly been adopted in the media with several feature films and documentaries have highlighted the event (The Ivory Game, Hugh’s Ivory War). It was a truly unforgettable experience, which I self-shot and have now begun to edit into a separate film alongside this production. Filming beside my heroes, both in the conservation and camera world was one of the highlights of the shoot. The worlds press and filmmakers were gathered to document it, and it was truly a sobering sight to see the 150 tons of ivory go up in flames.

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  1. Who wrote it and what inspired that?

The story of A Lion’s Tale began with my passion for lions and chance meeting with leading ape conservationist Ian Redmond.

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This love of Africa and felines started during my childhood, when I was encapsulated by the true story of George and Joy Adamson. For me, the purpose of making A Lion’s Tale was to emotionally engage and raise awareness – focusing on one of the major issues not only concerning lions, but all wildlife in Kenya. The original Born Free story captured the emotions of millions during its release in 1956, a time when our relationship with the natural world and ‘wild’ animals was viewed negatively.

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And so, whilst a large conservation movement was seemingly triggered with the momentum of a single film, it was the emotive driving force behind the true story about the real Adamson’s who released an orphaned lioness into the wild that led to actress Virginia McKenna to change her entire career and life plan – from actress to activist. I also felt it timely to produce with the upcoming ivory burn and Convention on the International Trade on Endangered Species meetings in Johannesburg. I didn’t want to write a set script; and by using the characters’ voices in the film I hope this has allowed audiences to connect with and care about the cause – not be lectured on it. The major theme of the film is hope – an emotion that all humans can relate to and a message that I believe everyone involved in the filmmaking and conservation industry can use as a device to inspire and drive change.

  1. And who produced it and pulled the project together?

I was the producer of the project and responsible for all the script-writing, scheduling, budgeting, interviewing, shooting, etc. which did take extensive planning. After conducting all the research, calling and making the contacts; getting out on location was thrilling but accounted for only 20% of the production! Logistically it was challenging, Meru National Park is not a well visited park like the Maasai Mara or Amboseli. I booked a direct flight from London Gatwick to Nairobi to go and film at the Born Free office based there, the ivory burn and then a small carrier plane into the heart of Meru for the lions.

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Upon descending Meru, all I could see was a small office – no runway as such but more of a dirt track – then suddenly a giraffe galloping away from us in attempt to avoid a collision! However, the Born Free team and Kenya Wildlife Service were remarkable, they helped make the shoot a success – driving me to all the locations within this most beautiful and underrepresented of parks. The ivory burn was undoubtedly the hardest to get permits for; but with a lot a patience and incredible support from the Born Free’s president (CEO) as well as one of my contributors, Will Travers, I was fortunate enough to be able to film at the historic event.

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  1. Did you have much in the way of money to play with?

Not at all! I calculated a rough budget of £3000, as most of my negotiations brought the prices down and the park fees to film were waivered in return for me editing a separate version for them. This may seem ludicrous to most drama filmmakers, but in wildlife the budgets are far smaller and so this is where precision also plays a part throughout the production process. In total it cost £2600 for a 10 day shoot – this of course excludes all the pre-production and post costs as I was the one researching, filming, directing/producing, editing, grading, sound mixing; however the music was beautifully composed by MA student Richard Collins as part of his course. The facilities were provided by my university and the training in advance, but also a lot of practical reading and watching hours and hours of ‘How to…’ videos! Kit was also borrowed from the university and so most of the budget was spent on flights and accommodation. I did however set up a crowdfunding campaign and managed to raise half the funds to go; kind support from family, friends and strangers alike. IndieGoGo was the platform I used as it’s less risky if you don’t hit your top target.

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  1. And what were your kit choices for this film?

Kit wise I used what was available at university; the Sony FS700 with the kit lens (18-200mm f/3.5-6.3), the 50mm f/1.8, 100mm Canon f/2.0 primes and the 100-400mm with the EF metabones adaptor. The telephoto was crucial for getting close to the action when it would have otherwise been too far and dangerous. This was especially the case with the lions! For sound; radio mics, Sennheiser 416 with the 522 mixer, and a Tascam for good measure – the latter was used to record atmos in the field. The wild sounds of Kenya truly are as vivid and vibrant as you would imagine. I loved recording the young group of school children who sang to us, it stirs up many joyful memories when played back.

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The film was edited on Premiere Pro, Pro Tools, and graded in Da Vinci. In hindsight, I would have loved to have taken an DJI Ronin MX gimbal, FS7 and a Phantom 4 Pro drone for the aerials; but very grateful for the access to the kit we had, especially as students. You are only ever truly limited by your own imagination.

  1. Where does it sit alongside the rest of your portfolio of work?

In terms of technical difficulty, time scale, and aspiration to make – it’s right up there! As I am sure many of you reading this have experienced, we are our own worst critics. However, this is one project that I was excited and dare I say it, proud to have made. It’s been a life-long ambition to meet my heroine Virginia McKenna, and never thought I would get to experience the true Born Free story alongside the incredible people who keep that spirit of the Kenyan wilderness alive.

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  1. So where are you with the film right now?

The film is now complete, however there are a few colour grading tweaks being done by a professional, as I now have the confidence to hit the bigger festivals! It was something that I lacked skill-wise, and could only grade and colour correct to a certain extent. I’m looking forward to the festivals and so far, it’s collected awards at six in the US, UK, India and Spain; winning recently at the Wild Film Fest in Falmouth. But more importantly, it’s been shared in the schools back in Meru where it was filmed, and where the real difference in changing attitudes towards these amazing animals can be made. They are the generation that can make all the difference.

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  1. How is it looking at this stage in the game?

All finished! It took me 10 months in total, with my fellow course mates and I recently enjoyed a screening of our films at the Everyman theatre in Bristol. It was incredibly rewarding to see in on the big screen with family and friends, as well as some BBC staff who came to support us. A project that you are so involved in does, to a certain extent, take over your life for a while – but it’s such an incredible feeling to see the end creation. Although I always say that if I didn’t set myself a cut-off point, I’d be forever editing! I received a heartfelt letter from Virginia McKenna, my main character, about how much she enjoyed the film – and that was very special indeed as she had a huge influence on me when I was growing up.

Incredibly exciting day at the #premiere of #alionstale @ the #Everymantheatre #Bristol😀😎🦁🐾🎞 #mawfonlocation

A post shared by Tania Rose Esteban (@tania_esteban23) on

  1. And how do you plan to promote it given that this is such a competitive marketplace?

I plan to promote it through a variety of social media platforms; Twitter, Instagram, Facebook, etc. and by connecting with influential Born Free supporters who can use their media presence to share and connect the film with the intended audience. Equally by continuing to enter festivals, I hope to promote it further worldwide. I also shot some 360 VR ‘behind the scenes’ clips to showcase on my website, especially during the ivory burn. Tapping into this market is key to reaching the younger audiences or those not necessarily interested in wildlife. During the run up to the film’s creation, I built up an online audience offering exclusive clips and images from the shoot as well as other stages of its development. It’s really important to engage with them and respond to what they have to say; as well as offer any advice. They also want their voice to be heard.

  1. Can you tell us about the other projects you’ve been working on?

Screen Shot 2017-02-06 at 19.05.27At the moment, I am employed at the BBC as a researcher with the digital team – one of the most innovative, creative and energetic group you’ll meet at the Natural History Unit! I’m loving every moment, most recently we released exclusive Snapchat stories for Planet Earth II in the US, and now I’m working on another digital project associated with the Blue Planet series. It’s incredibly exciting as you get to help out in various productions with different roles. Film-wise I do have a couple of personal project ideas in the pipeline, and I am very keen to shoot another short using the superb Panasonic GH5 – watch this space!

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  1. How do they differ from this one?

They differ in that they are not located in Africa! I’ve always been incredibly drawn to the continent but now have storylines I’m researching in Australia and Japan, both having more of a cultural-human element to them. However, another short I’d love to shoot is more of a pure wildlife blue-chip style, and I now have access to better equipment and financing to facilitate the projects.

  1. What is your favourite genre and why?

I’m a little biased when saying I adore making natural history, but it’s something I live and breathe every second of the day. For centuries, humans have told stories to make sense about the world- illuminating behaviour, making order out of chaos and to create moral meaning. It’s the way we can comprehend and pass on information, with which we have the insatiable need for form and structure in the way we tell them. Natural History has been documented for thousands of years through visual, physical and audible means, whether through the primitive Stone Age depictions of a hunt through cave paintings, to the now pioneering ultra-high definition wildlife films. Nature is endlessly fascinating and beautiful, and as a curious person it’s something that I’m always passionate and keen to share with others. I am certain most of us have this desire to learn about the world around us. I do of course enjoy watching a great variety of programmes and films; adventure, comedy, sports, fact ent, animation and action! You can learn many lessons from different genres.

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  1. Are there other genres that you’d like to tackle?

Natural History will always be my passion – but I do believe you can cross-pollinate genres and get interesting results. A superlative example the award-winning success Virunga directed by Orlando Von Einsidel; where wildlife documentary meets investigative journalism. It combines elements of “The seven key steps of story structure” as described by screenwriter John Truby, and regardless of it being a non-fiction film, Virguna also contains strong dramatic elements and a classical story structure of good versus evil. Battles depicted through the civil war and conflict between the park rangers and the oil companies are also tied in with the need to survive, along with the desire to exploit natural resources for profit. These all conjoin into a single cause and effect pathway through the combined use of a ‘run and gun’ shooting style and profound emotive pauses. It would be interesting to try a more daring, journalist approach with a conservation story – thrilling audiences by being immersed right in center of the action.

  1. So what is the filmmaking climate like in your neck of the woods?

Wildlife filmmaking is quite different to drama in my experience. Whilst we are adopting more cinematic techniques and technology using gimbals and aerials to create a parallax and dynamic edge; the set-up times, cast (!), budgets, and approach are quite different. I worked recently on a drama set as a camera assistant and found the whole thing fascinating; there certainly are no repeat takes when filming a wild animal in action! Equally, whilst in drama you have many specialized roles such as focus pullers, gaffers, and make up; wildlife crews are noticeably smaller as costs for location shoots would soon quickly rise – budgets are noticeably smaller. Most crews are a jack of all trades, and you learn quickly how to be as multi-skilled and useful to a team as possible. It’s the most incredibly rewarding and thrilling industry, and you never quite know what animals you will see and how they will behave. If you’re lucky, you can capture unique behavior that’s never been seen before.

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  1. Are you at the stage of making any money from this as yet?

No, I decided that this project would not be for profit, despite my access to the ivory burn. I wanted this to be an educational and inspirational piece and shared far and wide; available to anyone with an interest in wildlife and Africa. Now that I know I can make a short film – next time may be different!

  1. So where do you see this filmmaking route taking you in the future?

I hope to follow in the footsteps of some of my filmmaking heroes; Sophie Darlington, Sue Gibson, Justine Evans – the best female camerawomen in our industry! But equally, I do want to pursue my passion for producing and continue to create compelling stories. I recently met the producers who worked on Planet Earth II who were incredibly inspiring- their work is truly in a league of its own. David Attenborough of course has been the greatest source of inspiration; and If I can make entertaining, emotive and compelling films that inspire others to want to make even the smallest of positive differences on our beautiful planet, then I’ll be a very happy earthling indeed.

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From Shoals to Social media: Global Intelligence, a Science to predict and create the future

Swarms of bees, shoals of fish, flocks of birds and a rowdy crowd of students. Ever wondered what fish and medical decisions have in common?

 

The ability to congregate and act collectively as a group- collective intelligence (CI). The study of CI in humans is a relatively new field in biology, which describes the universal distributed intelligence which arises from the collaboration and competition of many animals and the ability of an animal group to perform a wide variety of task. Scientists for centuries have been fascinated by the theory and mechanisms behind which such behaviour arises. Originally during the 1970’s psychologists and sociologists were primarily interested in looking at an individual’s viewpoint, how they are influenced and change their decisions based on others, peer-pressure and bias.

However the more modern consensus proposed by biologists focuses on the information that each individual has which, above a certain threshold, will take into account other individuals decisions as well as their own to result in one collective movement. Several mathematical models have been used to describe the complexities seen across nature, from the movement of birds to large herds, and is radically transforming the way we share information, communicate and work.

 

The possible use and value of tapping into the CI of species is endless. Biomimetics in particular has been implemented in many different areas of science to make our lives easier and to solve complex tasks. For instance, medical decisions with true and false positives, has recently concluded that the opinions of 3 skin cancer doctors can match that of the best qualified doctor. In terms of the use if this information, society will have to decide whether or not it’s worth paying the extra money to invest in more accurate decision making in medicine.

This basic principal can be seen in shoals of fish when deciding whether or not to flee or stay when an approaching shadow looms. An individual would be stuck in this false or true positive feedback loop on deciding whether or not it should stay or leave, where it could either gain or lose a feeding opportunity. Living in groups beaks this feedback loop as each follows its next nearest neighbour, above a certain threshold number.

The nutritional state of the fish will determine their position within the shoal. Those that are hungry with remain near the front or periphery, at the risk of being predated. Those that are well fed will remain at the centre but at the cost of gaining less food. This, with the simple “nearest neighbour” rule, means shoals take on information around them as well as their own personal preference and move in that direction to form one collective movement with the shoal.

Equally, humans have always possessed a deep desire to predict the future and indeed the collective intelligence of humans through the power of the media is showing promising signs of being able to just do that. Through analogous mechanisms seen in the natural world and the application of mathematical metric models to translate similar mechanisms into our modern world, CI has begun to radically transform the way we live our lives for the better. Can we tell the future with science? It seems that we can.

Prediction markets are used in politics for example, whereby large sums of money will be placed on different markets according to their own personal research and information, the decisions of others (in terms of how much they are willing to bet) which results in the resolution of a decision or problem. The hypothesis here is that the collective wisdom of many people is far greater than the conclusions of the few. Political betting has only recently made it to the UK compared to our American counterparts who have taken advantage of this powerful predictive tool, with correct predictions for almost every election between 1868-1940. Indeed our most recent elections in the UK was correctly predicted by the Betfair market, whilst the polls where postulating Ed Milliband would be at No.10, the markets it seems had the best information regarding the trends, and Mr Cameroon did remain Prime Minister as predicted.

Companies such as “Recorded Future” actually use the information already made available on the internet by people, through powerful data mining and search engines- to predict future trends with remarkable accuracy, as seen on social sites such as Twitter. Rather than the traditional prediction markets as mentioned above where peoples opinions are asked with responses to questions, the use of “web intelligence” to look at what people have already said on the internet is search via automated speech processing.

Others companies and institutions such as the Massachusetts Institute of Technology work have produced Climate CoLab, were it sets challenges and asks its members to think of collective solutions to tackle global issues related to climate change and energy use. It is a crowd-sourcing platform where citizens work with experts to create, analyse and propose ideas. The members of the community are invited to submit their proposals as well as make comments on others, which then are evaluated by experts to select the most promising ones. The MIT centre for collective intelligence stands at the forefront of this revolutionary use of global intelligence and information and uses new technology to harness the power and change the way people work together.

In terms of design, solutions to smart cities and how we can monitor traffic more efficiently through social media as well as pay for parking through mobile devices has already sparked interest in many countries with increasing congestion due to urbanisation.

This will inevitably determine how we are able to keep up to pace with our ever increasingly changing world, having implications for society, economy and our environment. So next time you tweet…you may be helping to support future decisions. And that it’s not who you are but what you know which feeds into this most fascinating and little covered area of scientific research.

Urban Bat Ecology

 Urban Growth

The rapid global urban population growth seen in the last 65 years, from 746 million to 3.9 billion in 2014, has had significant impacts on bat species richness and abundance (WUP 2014, Kunz et al 2007), due to habitat loss, fragmentation, degradation (Altringham, 2011), chemical pollution, barrier effects, introduction and facilitation of invasive species and a decline in prey species (Wickramasinghe et al, 2004, Lentini et al, 2012, Berthinussen & Altringham, 2012). Many studies are currently looking into the possibility of using bats as bioindicators of environmental change (Wordley et al, 2014, Russo et al, 2014), due to Chiroptera being the world’s second most speciose mammalian order (second to Rodentia), numbering 1232 species (Kunz et al, 2011).

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Equally, their widespread distribution and sensitivity to even minute perturbations means they could reflect the status or possible risk of such change in other species (Jones et al, 2009). Some of the responses to change can be seen with declines in abundances, population size, range distributions and behaviour (Altringham, 2011). Thus, it is important to determine the relative abundance of bats in urban areas compared to rural and suburban, and see whether an association with particular urban features are limiting or enhancing their ability to forage and roost there. This information has vital applications for conservation, as 82% of the UK is urbanised and is steadily increasing (United Nations World Urbanization Prospects, 2015). Thus, policy makers with knowledge regarding the ability of certain bat species to adapt (synurbic), or not (more vulnerable and sensitive species) to one of the greatest land use changes seen in the last century, can act to reduce the impact by lobbying with businesses, developers and politicians (Altringham, 2011, Russo, et al, 2014).

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Importance and impacts of an urban landscape on bats- Urban foraging and roosting

Bats form some of the largest seen mammalian assemblages, (Jones et al, 2009), with up to 40 million in a single cave-roosting colony (Seimers et al, 2001). The potential of urban areas being suitable areas to provide bats with useable roosting and foraging habitats is becoming an ever more prevalent area of research. Thus, it is of vital importance to study how bats are using such anthropogenic landscapes (Bellamy et al, 2013). It is essential that research from a wide variety of urban landscapes is conducted in order to assess the relative importance of particular variables and landscape features, as some are more important to different species, which each exploits the landscape differently (Altringham, 2011, Coleman & Barcley, 2011). It is this specificity of each species responding to urbanization differently which is vital to conservation and management policy. Each bat has evolved is perfectly adapted to each habitat, in terms of wing morphology, diet (ecological niche), echolocation call, hibernacula and behaviour (Altringham 2011, Threfall et al 2008). Thus some exhibit behavioural plasticity and can adapt to urban environments, enabling them to effectively exploit their habitat without the disruption of roads, light pollution or buildings (Russo and Ancillotto, 2014, Stone et al, 2011). This has been seen in bats with long narrow wing morphology with a high wing loading, as open air foragers are largely unaffected by urbanization (Norbeg & Rayner, 1987).

Hunting phases of bats. Search phase involves a high frequency component (45-55kHZ) as well as CF constant frequency with longer pulses as it detects prey. Then the calls increase in frequency with additional harmonic components as the bat approaches its prey. Then terminal phase the bat can emit calls at 2ms as it hones in on it.

The ability of synanthropic bats to dominate urban foraging areas can be problematic for the less well adapted species (Silvis et al, 2014, Russo and Ancillotto, 2014). Some studies even suggest urbanization may result in greater competition between the synurbic and less well adapted species, as implicated by Arlettaz et al (2000). The study suggested that the decline of the Rhinolophus hipposideros in Wales may be due to the expansion of Pipistrellus pipistrellus, whose populations have increased as a result of greater feeding efficiency with artificial lights (Warren et al, 2002, Lacoeuilhe et al, 2014), normally avoided by the lesser horseshoe bat. Equally, in one study investigating the activity of insectivorous bats in Panama Canal, it was shown that only a few dominant Molossus were able to adapt to urbanized areas due to their high wing loading and aspect ratio (Jung et al, 2011). This was in contrast to a majority of clutter-specialist species recorded which foraged within the forest and the forest edge.

Advantages provided by artificial roosts in urban areas include homoeothermic benefits, in particular for pregnant females by reducing the energetic costs of maintaining their body temperature within the thermal neutral zone (Lausen & Barcley, 2006). Therefore the potential to provide bats with artificial roosts is of interest to many conservation bodies, which aim educate and encourage public concern (Altringham, 2011). Artificial bat boxes have been shown to be particularly exploited by opportunistic and synurbic P.Kuhii (Angelli et al, 2011). However, the lack of rigorous scientific testing of their effectiveness is yet to be determined in lesser adapted species (Altringham, 2011), and with thorough monitoring and further studies into ‘bat box’ preferences, a more valid account of their potential use may be of value to policy makers (Russo & Ancillotto, 2014).

Importance of Water in urban areas

Bats are vulnerable to evaporative water loss as a consequence of their morphology and large surface area to volume ratio, as well as high energetic costs with the ability to fly (Razgour et al, 2010). Within urban areas, open artificial sources such as ponds, ditches and swimming pools provide bats with fundamental opportunities to drink and forage. Certain species show preferences over these larger, less cluttered and open bodies of water (Seimers et al, 2001). The reduction in pulse-echo overlap, ability to detect spectral shift and high insect abundance over still water sources (Altringham, 2011) can attract large numbers of bats to urban and modified sites (Vindigni et al, 2009). Such examples can be seen in North Carolina, where studies looking at the importance of managed water bodies over natural wetlands revealed significantly higher bat activity by heliponds, despite equal densities of insects at both sites (Vindigni et al, 2009). Equally, studies on Greek islands showed that bats will also use artificial water sources such as swimming pools due to the lack of natural sources in such arid habitats, with minimal annual rainfall (Davy et al 2007).

If you want to find out more about how YOU can help bats, head over to the Big Bat Map and the Bat Conservation Trust!

http://www.bigbatmap.org/pages/help-count-bats.html

The value of bats

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Apart from being amazingly cute!

Exactly a year ago today I conducted my research on British bats around North and West Yorkshire regarding their habitat selectivity across multiple scales in rural and urban environments. I still can’t believe how fast it’s all gone in the past 10 months! I will be posting up some articles on exactly what I did and how you can also get involved with conserving these fascinating little mammals of ours too, but first I want to tell you WHY bats are so important to us all.

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Just hangin’ around… Pipistrellus pipistrellus (Common Pipistrelle)

Apart from justifying the value of bats in terms of their diverse nature and unique evolutionary history which has lead to the only powered flight seen in mammals (Fenton et al, 1997), bats provide a range of ecosystem services and benefits to both the environment and humans (Altringham, 2011). The Brazilian-free tailed bat provides one of the largest-scale suppressions of insect pests in the world (Kunz, 1989). During their migration northwards each spring, Tadarida brasiliensis forage on cotton bollworms, saving the US economy over $23 billion dollars in terms of preventative damage to cotton and the reduced cost of less pesticide use (Cleveland et al 2006).

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In Asian markets, over 70% of the fruit sold is pollinated or seed dispersed by bats, in particular the Durian fruit which is worth $2 billion (Kasso & Balakrishnan, 2013, Altringham, 2011). The alcoholic beverage, Tequila is derived from the Agave tequilana and is pollinated by the lesser-long-nosed bat, providing a source of income of for many Mexicans (Kunz et al, 2012). Guano is a source of high concentrations of phosphorus and nitrogen, which is one of the primary limiting nutrients of plant life. Deuchamp et al (2009) studied the potential benefits of the ‘pepper shaker-effect,’ a hypothesis where bats flying from nutrient-rich regions to nutrient-poor habitats, redistribute the guano and act as a mobile fertiliser. Several countries sell guano as fertilisers and can be a main source of income in poorer regions (Altringham, 2011).

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The lesser-long-nosed-bat hovering over a cactus flower.

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Ecotourism also boost the economy, for example as seen in Congress Avenue, Texas which generates $12 million annually (Pennisi et al, 2004). Medicine is also derived from the Vampire bat’s salivary enzyme, desmoteplase which acts as an anticoagulant for post-ischemic stroke patients (Furlan et al, 2006). This was initially trialled on mice in 2003, and was found to extend the time required to administer tissue plasminogen activator during the post-stroke period from 3 to 9 hours (Schleuning et al, 2008).

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Molecular structure of desmoteplase.

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Other aspects of bat biology providing benefits to humans include the development of the ©UltraCane, a device that enables the blind to detect oncoming objects. Developed by researchers at the University of Leeds, it was based on the echolocation calls of bats and has helped thousands of visually impaired people (Scheggi et al, 2014).

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The Ultracane

Also mentioned is their value as bioindicators of the overall health of the ecosystem, which can be seen with their importance in ecological networks and high trophic level, if removed, cumulative and rippling effects can be seen lower down trophic cascades (Jones et al, 2009).

I hope you can see how incredible these little mammals are, and stay tuned to find out about the amazing world of bats in future posts!

Check out our Ecosapien video on bats:

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Darwin VS Mendel: Scientist showdown

‘Who has made the greatest contribution to biology, Gregor Mendel or Charles Darwin?’

There is no doubt that the irrefutably intrinsic contributions of both these remarkable scientists enabled future generations of scientists to make further advances in biology which has shaped our lives worldwide; but to what extent does Charles Darwin’s theory of evolution and natural selection or Gregor Mendel’s set of laws of inheritance outweigh each other in terms of importance?

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Charles Darwin (1809-1882) was ‘a man born to explain the astonishing diversity of life and in doing so would revolutionise the way in which we see the world and our place in it.’ Indeed a revolutionary biologist, his pivotal idea was to be inspired on his journey to the Galapagos in 1835 aboard the HMS Beagle. Darwin collected a plethora of different species and meticulously noted minute differences between the species of the Galapagos and the mainland of South America. The evidence suggested that each species had not been independently formed by a creator but had diverged from a smaller group of common ancestors within the major animal kingdoms (Bowler 1983). His ideas of natural selection developed during 1837-1838. The proposed theory stated that in all species limited resources lead to a struggle for existence either between or against other species members, this is known as intraspecific and interspecific competition (Fullick 2008).

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Variation within species influences the success of an organism; therefore species with more advantageous ‘variations’ will live to reproduce and pass on these useful characteristics to their offspring and will better enable it to survive in its particular environment; this is natural selection (we now know that variation in genetic terms means advantageous alleles which occur due to DNA mutations, gene flow and sexual reproduction). This process over time would lead to the elimination of the lesser adapted species and the survival of the better adapted ones and possibly a new species (this is known as evolution, however, Darwin did not directly call his theory this).

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It took 22 years after his voyage to the Galapagos, armed with a wealth of knowledge and a mountain of evidence to publish the world-famous Origin of Species in 1859 (Shanahan 2004). It is clear today that the extent of Darwin’s contribution of his theory of natural selection has greatly contributed to biology. We are now fully aware of the interconnections between species and how we evolved over time. This also lead to the discovery of continental drift, the ‘missing links’ within our earths history through fossil records, the age of the earth itself and inspiration for other biologists. Professor John Shine from the Garvan Institute of Medical Research stated that “Darwin’s theory was a fundamental building block for all modern biology…underpinning the way we think about a lot of medical and biology research” (Arnott 2009). Also in agreement of Darwin’s achievements is Professor Tim Flannery who concluded that what Darwin has done for modern science and indeed every living individual on the planet is “give us the context that created us” and I am inclined to agree with both leading scientists (Arnott 2009).

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However, many critics of Darwin argue that his contribution was not as great as that of Mendel’s and that Mendel was the ‘father of genetics’ (Mawer 2006). Gregor Mendel was an Austrian monk and biologist who experimented with peas. Quite like Darwin, he was a nature enthusiast and studied at the University of Vienna before returning to priesthood in the Augustinian abbey (Montgomery 2009). It was at the abbey where he began his famous experiments with peas. Between 1856 and 1863 he grew and observed more than 28 000 pea plants and identified seven characteristics showing discontinuous variation including flower position, pea colour and pod shape (Fullick 2008). He experimented by crossing the pairs of peas and recorded which characteristics were passed down onto the next generation, later presenting his results to the Brunn Natural History Society. In 1866 his papers on the subject were published describing the two fundamental laws of hereditary; these are known as Mendel’s Laws of Segregation and Independent Assortment.

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Mendel helped us recognise how organisms passed on their traits to their offspring. His idea of genes was as “discrete particles passed on intact from parent to offspring” (Walsh 2012) and although his great achievements were not noted until 16 years later by Hugo de Vries and Karl Correns, the significance of Mendel’s discovery has enabled our modern society to function as his research laid the foundations for the study of genetics. The Human Genome project for example was created as a multinational project to determine the base sequence of the human genome and many new ones have been identified such as those responsible for disease (Skinner and Lees 2009) which has lead to the development of target drugs benefiting millions globally. Mendel had read Darwin’s theory with interest but pivotally disagreed with the blending notion (Pangenesis- where both parents contribute fluids to the offspring containing the genetic material which is blended to create the new offspring, Walsh 2012) and this is the main reason for many why it was Mendel who was the greatest contributor to biology as he had no ‘gaps’ in his evidence (Leroi 2009). However, I would argue that although Darwin had difficulty in comprehending inheritance, part of his genius was to realise that not understanding inheritance was not a predicament for his theory of natural selection and he had sufficient evidence for it from his work on domesticated animals and plants as well as from communicating with other scientists.

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The world’s most influential biologists, “Darwin and Mendel were contemporaries to many and yet the initial acceptance of their ideas suffered very different fates” (Walsh 2012). Darwin theorized evolution and its complex traits (concepts from population and quantitative genetics) whilst Mendel was concerned with the “transmission of traits from a genetic basis.” Combining Darwin’s theory of evolution with Mendel’s genetics was the most important breakthrough in biology as it triggered a cascade of a whole host of other biological discoveries including DNA (Mayr 1997) the understanding that bacteria evolve which has enabled us to devise methods of dealing with the diseases that they causes and also the disentanglement of the complex relationships between animals and plants within communities enabling us to foresee some of the consequences when we start to interfere with them. I have found both these remarkable scientists profusely influential in my life and to many of my heroes. I therefore collectively deem both of these extraordinary biologists of equal importance in their contributions to biology, because not only have they revolutionised modern biology, they have inspired countless generations to further pursue  scientific knowledge, which is fundamental to the survival, well-being and enjoyment of future generations to come on an ever-changing planet.

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However, our planet is changing. Although natural phenomena have always influenced our climate, the surmounting evidence is unequivocal – Homo sapiens’ ignorance and reckless activities have caused a colossal shift in the natural order and balance of our ecosystems and inevitably the animals that previously co-existed within them. Threats such as climate change, the introduction of invasive species and habitat loss have decimated animal and plant species numbers over the past 100 years to such an extent that nevermore so has the study of zoology been pivotal in understanding the complex interrelationships between specie physiology, behaviour, evolution and development in order to protect their very existence. To be able to understand the intricate relationships animals have within their environment and observe their interactions within it is truly a blessing. I have been enchanted by all organisms from a very young age; to study them in depth would be a privilege and would give me the opportunity to return the same fulfilment by protecting them for future generations to see.

Major threats facing keystone species and the consequences for biodiversity

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Tania R.E –Esteban 1

School of Biology, Faculty of Biological science, University of Leeds, UK, LS2 9JT

 

The global threats facing keystone species is significantly impacting levels of biodiversity, due to the disproportionate effects keystones have on entire communities. They influence trophic interactions and provide ecosystem services of vital importance to the economic, social and cultural well-being of humans. It is therefore in our interest to establish the threats, the individuals most at risk, the potential cascading effects on ecosystems and how we are to manage them successfully in terms of reintroduction or mitigation. In this essay I review the major threats to a variety of different keystone species (at all trophic levels), examine how this influences levels of biodiversity and what effects they have on entire ecosystems. I also evaluate the current and potential management strategies that facilitate networks and allow them to be more resilient to future environmental change. Our knowledge of the concepts that underpin the fundamental basis of ecology can help us confront this as one of the greatest challenges in ecology.

Concept of Keystones

In different ecosystems, each specie plays a role within a community and can influence levels of biodiversity. However, the relative impact of each species can vary in terms of importance [27]. Such species that have disproportionate effects on ecosystems are known as keystone species [39]. According to network theory, keystones are intimately linked via ecological networks of highly connected and complex webs (Box 1, [9]). These include species at different trophic levels. Apex predators exert top-down effect on these levels, known as trophic cascades; whereby these strongly connected species indirectly influence community structure and ecosystem function [37]. The robustness of food webs to species removals varies, depending on the species and ecosystem type, where certain removals have greater impacts on ecosystem functioning and structure. Many apex predators are classed as keystone species because of the secondary extinction impacts of their removal on other species [7]. Predators directly impact upon herbivore numbers as well as indirectly through risk effects [34]. This then influences the relative abundance of producers- hence a ‘cascading effect.’

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Equally, predators sustain levels of biodiversity via the suppression of other competitors (mesopredators) through competitive exclusion, and allow other species to co-exist [20]. Predatory release occurs when the apex predator is removed, increasing populations of the less competitive mesopredator. This then leads to a decline in its prey. Predator-prey dynamics as well as competition between intra and interspecific species also influence the structure of the food webs [1, 27]. The length of food webs can also greatly influence the direction of the cascade according to the exploitation ecosystem hypothesis [11]. These natural processes can be perturbed by threats to apex predators- whereby the removal of such keystone species leads to the concept of trophic downgrading [10]. As well as this, there is an alternate stable; where ecosystems are disturbed to such an extent that the cascade shifts from its prior state to another- when a tipping point is reached [10].

Box 1- Network theory

The fragile nature of ecosystems has been explored by Sole and Montoya [36], on the basis that if the nodes that connect individuals are randomly removed in a network, it remains stable. However, when highly connected individual are removed, this results in cascading effects and interference throughout the rest of the network. These keystone individuals form the framework and structure of the network. In real ecological networks, strong evidence for the removal of predators are known to not only directly impact its prey, but also have indirect effects via top-down forcing. Ecosystems processes such as primary production, nitrogen cycling and the establishment of invasive species are also affected (Figure 3 [10]).

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Keystones – threats to a complex web of interactions

Habitat destruction

There have been major declines in biodiversity within recent decades, in what has been described as the 6th mass extinction event [27]. The threats facing keystones and the ecosystem services they provide are predominantly anthropogenic [19], and habitat loss is arguably one of the greatest [15]. For example, the Yellow and Black-Casqued Hornbills are both in decline, which has been correlated with deforestation in Nigeria as well as forest sections along the Ivory Coast [28]. This is problematic in that the genera Ceratogyma are key seed dispersers of fruiting trees, and play an important role in maintaining the heterogeneity of forests and species diversity via gene flow [28]. Because of the large spatial distribution of their territories [45], up to 22% of lowland tropical rainforest species are dispersed by the 3 hornbill species within this genera [23]. Cultural ecosystem services include traditional ceremony wear as well as other benefits to the keystone tree species, Ficus, which in turn provides economic services to local tribes’ people. It is also an important food source for other species within the ecosystem [23].

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Urbanization

Other threats to keystones include the urbanization of many habitats. Increased contact between humans and species drive them to exhibit behavioural plasticity and alter their behaviour [33]. A majority of studies indicate that increases in urban environments decreases species richness [35], due to disturbances in breeding patterns, anti-predator behaviour, fitness, selection of habitat and overall population size. This has cascading effects along trophic levels [2]. The black-tailed prairie dog, a keystone specie, contributes to the health of steppe habitats by mixing the soil. This increases plant productivity and landscape heterogeneity as well as providing coyotes with a food source [3]. Their overall numbers have decreased as a result of increased urbanization. However, in contrary to the risk-disturbance hypothesis, where increases in anti-predatory behaviours (such as vigilance) are seen, some populations exhibiting behavioural plasticity have reduced their vigilance due to habituation [12]. This has negatively impacted the vegetation due to increased foraging time, which has ‘rebounding’ effects back up the trophic cascade, on other herbivores and predators [33].

Climate change

Complex plant-pollinator webs are also disturbed by habitat destruction due to their sensitivity to perturbation [29]. This is the case with the keystone plant mutualist, Heliconia tortuosa,

Figure 1. The warming trend set to continue: (Left) Projected increases in temperature by 2081-2100 if mitigation and use of renewable resources is adopted. (Right) These are the predictions if the business as usual strategy continues (source: IPCC, Fifth assessment, 2014).

IPCC

which supports a variety of hummingbird species, and is considered a central node in this web interaction [17]. Recent work has provided evidence for the fragmentation hypothesis, where forest composition is fundamental to the reproduction of H. tortuosa. Thus, the reduction in heterogeneous landscapes due to deforestation is thought to alter both plant distribution and pollinator behaviour, leading to declines in both populations [29]. Equally, other systems have also shown that deforestation alters pollinator behaviour. Phaethornis hummingbirds will take longer flight paths to avoid deforest patches and agricultural landscapes, decreasing pollinator efficiency. This affects the survival of plant species dependent on this mutually beneficial ecological interaction- and has led to regional declines in biodiversity [16].

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Climate change also poses a major threat to the biodiversity of keystone pollinators (such as bats, bees and birds [19]). One third of the world’s crop production is met by the ecosystem services provided by insect pollinators [30], with agricultural pollinator services estimate to be worth £120 billion per acre, annually [40]. Phenological shifts are also increasingly being observed, with the impact evident in both pollinator and plant keystone species [4]. In Japan, seed production in Corydalis ambigua and Gagea lutea decreased due to the warmer temperatures causing them to bloom earlier, resulting in phenological mismatching with its key pollinator, Apis Mellifera. Consequently, this reduced pollination efficiency and success [31]. Climate change has also altered bee distributions and caused phenological shifts in their flight period. Predictions suggest that the spatial shifts in bee movements will be faster than that of its food resource, also causing phenological mismatching and decrease wildflower pollination [4]. Therefore, climate change poses not only a threat to the keystone plant-pollinators, but to other communities dependent on wildflower meadow species [31]. This highlights the fragility of these mutualistic interactions as key nodes in an ecosystem, due to their varying response to temperature change.

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A major issue with climate change is predicting the influence it will have on biological communities in the future [13]. The polar bear (Ursus maritimus) is an apex predator in the Arctic ecosystem which is very sensitive to changes in sea ice cover, where it hunts, migrates and reproduces [25]. The rate of temperature increase in the Arctic and northern regions have doubled in recent years, reducing sea ice cover [24]. In particular, over the past 30 years, the Western Hudson Bay has seen earlier ice break up as well as reduced snow fall (Figure 2). The impact on ringed seals (a keystone specie) with longer ice-free summers has subsequently lead to changes in polar bear behaviour [25]. The continuity of this pattern threatens seal pup survival as they are forced to swim for longer periods of time in open water, exposing them to predation [13]. Ringed seals provide polar bears with net wet weight calorific gains of 2.2-5.3 kcal/g [43], and the decreased recruitment of ringed seals has driven polar bears to target nesting birds, as they are unable to gain sufficient energy [25]. This warming trend is set to continue with possible increases in temperature of 5.0-6.4˚C by 2081-2100 (Figure 1, [24]).

Figure 2: Sea ice extent between 1979-2012 throughout the summer months. Evident loss seen annually. (Source: Iverson [25]).

Hunting and over-exploitation

Hunting and over exploitation is also a prevalent threat to many keystones worldwide. The removal of a keystone predator is a major cause of secondary extinctions, demonstrating the strong influence of top-down effects on lower trophic levels [10]. This was seen with the expatriation of the Grey wolf in Yellowstone during 1935 (due to hunting), which increased populations of elk as a result of predatory release [39]. Increased levels of browsing on aspen, cotton and willow saplings in riparian river systems led to a more homogenous landscape and reduced diversity [34]. The wolf played a vital ecosystem role by maintaining diversity as well as healthy numbers of mesopredator populations. Classic studies of the consequences of predator removal are also illustrated with sea otters [10]. Enhydra lutris was nearly hunted to extinction by Russian fur traders at the beginning of the 20th century, resulting in the predatory release of sea urchins, which reduced Kelp forests by intensively over-browsing [42]. However, with the return of the otter during the 1970’s to certain areas, the recovery of the kelp forests was observed due to the effects of top-down control on urchins. The kelp populations in regions where otters were unable to recolonize did not recover [11], demonstrating how the impact of hunting can alter and result in the simplification of food webs.

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The general pattern of global declines in apex predators is a cause for concern, due their strong connectedness in ecosystems and influence in altering the stability of food webs [19]. This is less well studied in marine ecosystems [20]. For example, sharks are apex predators in marine ecosystems [22], and are threatened by hunting. Demand for shark fin during the 90’s increased mortality rates by 80%. Many debate the function of sharks as keystone predators [8], however more recent studies suggest that although not all shark species can be described as keystones, some are key in structuring some ecosystems [44]. Indeed, strong arguments made by Estes et al., [10] concluded that the top-down effects exerted by apex predators are equally as influential as bottom-up effects. In Western Australia, Tiger sharks are considered a keystone apex predator; as mesopredator diversity (dolphins) and herbivores (dugongs) abundance are indirectly affected by the “seascape of risk,” as well as by direct predation [20]. 15 years of data collection in Shark Bay has supported the idea that the non-predatory effects of top apex consumers (predator keystones), play a pivotal role in influencing ecosystems [10]. Thus shark declines are affecting mesopredator numbers and behaviour, with unknown consequences on the rest of the aquatic communities [44].

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Clearly, hunting apex predators can have detrimental, aggregating effects on lower trophic levels, both directly (via predation) or indirectly (through the landscape/seascape of fear concept). Equally, the idea that keystone’s play a role within and across communities [27], was seen with the decline of sea otters in the Aleutian archipelago populations due to increased predation by Orca [42]. The overexploitation of fish stocks in these waters in turn reduced populations of pinniped that fed on them [11]. This altered the orcas behaviour which began targeting otters as an alternative food source. Kelp forests once again declined as urchins were free of predation. This is known as the exploitation ecosystems hypothesis, where the food-chain length determines the level of influence and control top-down or bottom-up systems have in the primary productivity of ecosystems [10, 11].

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Future: Management, mitigation and reintroduction

Problems

In terms of keystone species, the challenges of managing and mitigating their decline arise due to the complexity and interconnectedness between the many species they affect within ecological communities [5]. For example, managing the declines of seed dispersers is hard due to the large spatial ranges of their territories and difficulty in quantifying dispersal rates [23]. The extent to which urban-adapted keystones will affect the rest of the community depends on their ability exhibit behavioural plasticity and adapt, which varies between species and landscape scale [35].

The threat of climate change is also difficult to predict, thus is hard to prevent plant-pollinator loss in the future as phenological shifts continue at different rates [4]. Similarly, the uncertainty surrounding model projections of sea ice loss threatens the future survival of many Arctic species [25]. In aquatic systems, the lack of protection out of marine conservation areas and the extensive movements of keystone predators such as sharks, creates problems in managing and mitigating their decline [21, 22].

Equally, the overall concept of what constitutes a keystone species provides difficulties in management [7]. The definition can be broadly used to describe a spectrum of keystone types, which is confusing and problematic for conservation policy [7]. With an increasing number of species being given ‘keystone status,’ the lack of consistency in defining them more scientifically is rapidly becoming a challenge in itself [27].

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Identification of which trophic direction is most influential in affecting levels of biodiversity within communities is controversial [10]. Often, it is dependent upon the ecosystem as well as the keystone specie. Some argue that primary production controls ecosystems bottom-up [18]. Others believe predatory top-down control is more influential, and is currently gaining more support due to the mounting evidence that global predator declines have significant impacts on communities and ecosystem processes (Figure 3, [10]). However, even if top-down systems were recognisably more important in structuring ecosystems, it is hard to determine the most prevalent impact predators have in influencing interactions within food webs- directly (through predation/lethal) or indirectly (risk effects/non-lethal [34]).

Figure 3: Indirect impacts of apex predators on different ecosystem function and processes (Source: Estes et al [10]).

Indeed, this is the case with sharks, where the importance of risk effects might be underestimated [26]. In terrestrial ecosystems, the ‘landscape of fear’ as well as direct predation by wolves is being taken into account in studies of natural systems, (eg: Białowieża Forest, Poland) in order to consider the nonlethal effects on herbivores [32]. Proposals by Manning et al., [34] suggest that controlled experiments in the Scottish highlands would provide much needed data and viable evidence for their reintroduction. However, public opinion is often divided in terms of reintroductions [37], and the funding and costs of trial experimentation are deemed wasteful [32].

The nature of predicting ecosystem response with the removal of a keystone is also very difficult when taken from a stable environment- where prior knowledge of the response in unknown [36]. Only a few studies have examples of networks that are partially mapped [5], and the substantial lack of data on a range of ecosystems makes management difficult [36]. Much earlier research does not indicate the strength of each trophic link, thus it is difficult to compare to the current consistent and empirically accurate data. Even when disrupted, other factors such as intraspecific competition can alter the response, and may take many years for the effects to propagate in the ecosystem [10]. Current strategies by the US Endangered Species Act fail to incorporate this [41].

Possible solutions?

It is vital that scientists are able to quantitatively asses the relative contribution of each proposed keystone [36]. Only then can policy makers implement management strategies that target and focus on protecting species that have the most important functional role- rather than the rarest specie [27]. We must also therefore demonstrate their functional importance before policy-makers act on the impetus of the analogical term of a keystone [7]. Of equal importance is understanding the connectivity of networks as well as attempting to mitigate the threats facing keystone apex predators. The geographic spatial scales at which natural or previously manipulated experimental removal experiments varies enormously, thus must also be considered in future reintroductions and management plans [39].

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As already established, complex ecological concepts are hard to manage as many factors feed into the function, stability and persistence of food webs; including biotic and abiotic factors [10]. It is clear how important abiotic interactions greatly influence ecosystems and community structure and function, and must be considered if we are to manage and mitigate the effects of current and future climate change [19]. Therefore, as the fifth assessment by the IPCC suggests, anthropogenic climate change policy should focus on mitigation by following resilience pathways and realising adaption measures towards a more sustainable future [24]. If we are to reduce the number of extinctions, policy must also address the source of the problem; fossil fuel consumption, to mitigate the severe effects it could have on vulnerable keystones and their habitat [24].

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Other concepts such as network theory have helped explain how the systematic targeting of particular keystone individuals is far more destructive than random removal [36]. Therefore fisheries must implement this into their harvesting methods and reduce their impact on sharks by implementing annual moratoriums to prevent over harvesting. This will require international cooperation to account for the spatial movements of these keystone predators [44].

Conclusion

The threats facing keystone species may arguably have the greatest impact upon ecosystem function and stability globally [10]. Keystone predators in particular play an important role as their loss is a cause of many secondary extinctions [21]. The complexity of these networks cannot be undermined, and scientists must now be able to predict and further assess why certain keystone species are more robust or more at risk from collapsing early on than others. This will determine which species will have the greatest impact upon the stability and function of communities [46]. Additionally, completion of fully described networks will need to be of a multidisciplinary manner, in order to expand upon the current knowledge of these systems. Mitigating the threats as well as assessing the success of keystone reintroductions in influence levels of biodiversity is also key [44]. The reduction of harmful human activities is also necessary in order to prevent future extinctions and declines in biodiversity [24]. Ultimately, the solutions to the challenges facing keystones and ecosystem function are not simple. However, further knowledge of how these systems work and the implementation of efficacious management strategies will lead more efficient restoration and protection.

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Loss of Apex Predators

News & Views

Loss of Apex Predators in Dual-Apex Systems

By Tania Esteban, Samuel Ross, Jessica Rushall, & Louise Shuttleworth

LION2

Apex predators are in global decline. The description of possible complex interactions between apices in dual-apex systems calls for further research.

Apex predators occupy the highest trophic level of an ecosystem, thus do not have natural predators themselves. They are capable of affecting ecosystem functioning through consumer-control and strong trophic interactions. There are currently unknown interactions between apex predators and mega-herbivores in systems where both are present. Because of this, the loss of apex predators from a ‘dual-apex system’ could affect communities in a highly complex manner. The decline of apex predators should be considered in systems with both mega-herbivores and apex predators. Tambling et al., (2013) explored this concept in an African ecosystem where lions (apex predators) and elephants (mega-herbivores) co-exist. In this article we discuss the potential effects of apex predator loss in this ecosystem.

trophic cascasde

Mega-herbivores perform important functional roles in ecosystems. For example, elephants alter plant community architecture through trampling and overgrazing1. Direct aggressive interactions between elephants and other animal species also occur in these systems2, highlighting the key role of mega-herbivores in influencing species dynamics. Elephants also have indirect impacts on other herbivores through exploitation competition over resources, and depending  on the  system,  are sometimes able to outcompete smaller herbivores1.

meg herbs 2 meg herbs 1

Figure 1. Weighted trophic interactions between species in the presence of apex predators: (a) with; and (b) without mega-herbivores. Interaction strengths are depicted by line thickness.

Lions are important apex predators in African ecosystems. They exert consumer-control, through predation on small and medium/large sized ungulate species, such as duiker and kudu respectively1. Like elephants, lions are classed as a flagship species because they are globally renowned, captivating, and of conservation concern. Lions are classed as vulnerable3, and are in decline because of hunting and persecution; diseases including CDV; and habitat loss due to agriculture and urbanisation4. If lion numbers continue to fall, large detrimental impacts on these ecosystems might be seen.

In multiple apex systems, interactions between apices are likely. Despite a lack of literature on the topic, there are potentially undescribed interactions between species occupying these apex roles.

Apex predators are likely to interact indirectly with other ‘apex consumers’ including mega-herbivores5. One of these indirect interactions can be facilitation by one apex on another; for example facilitation of predatory success of apex predators by mega-herbivores through environmental modification1. Another of these indirect interactions between apices would be the loss of one apex from the system. It is widely recognised that the loss of consumer-control has widespread effects, with the impacts of this loss propagating through the ecosystem. On a larger scale, trophic downgrading is a global threat, as systems are driven towards simplicity when consumer-control by apex predators is lost5.

In an African thicket ecosystem, Tambling et al., (2013) studied the interaction between lions (apex predators) and elephants (mega-herbivores). In this system elephants facilitate predatory success of lions through overgrazing and trampling of dense thicket vegetation. This allows access into the dense vegetation, which lions utilize because they are sit-and-wait predators. Lions will preferentially select for foraging habitats that maximise cover, over abundance or value of prey6. Therefore, modification by elephants facilitates an increase in encounter rates between lions and their smaller ungulate prey, as these  species predominantly inhabit this thicket vegetation1. In the absence of mega-herbivore facilitation, lions predominantly feed on larger prey species, as they do not have access into the dense thicket vegetation in which the smaller species reside [see figure 1].

As briefly discussed by Tambling et al., (2013), loss of apex predators in these systems could lead to multi-directional trophic cascades. Compared to unidirectional trophic cascades, impacts of predator loss can radiate through the system in a nonlinear manner. For example, apex loss could propagate down through trophic levels and ‘rebound’ back up towards the second apex (mega-herbivore) through changes in populations of smaller herbivores.

In a classic trophic cascade, apex predator loss results in increases in herbivore populations7. The extent of population responses to predatory release depends on ecosystem structure. In the African thicket ecosystem where mega-herbivores facilitate lion predatory success on small ungulates, if lions were lost from this system, the resulting population changes of small herbivores would be greater than in the absence of facilitation by elephants. Where elephants are not present, lions mostly cannot access small prey species that frequent dense thicket vegetation so they predominantly prey on larger ungulate species1, resulting in greater proportional population increases in larger ungulates if predatory release were to occur.

Following the exploitation ecosystem hypothesis, if consumer-control is lost, systems are limited purely by primary productivity so the extent of primary production determines trophic complexity8. If lions were lost from a dual-apex system, the ‘second apex’ would likely be affected, as mega-herbivores would face increased competition due to predatory release of other herbivores [See Fig. 2a]. Systems that support mega-herbivores face increased herbivory initially, so when apex predators in these ecosystems are lost, mega-herbivore populations are at greatest risk of collapse due to competitive exclusion of these species with low rates of secondary production9.

Although Tambling et al. (2013) studied facilitation in dual-apex systems, as far as we are aware there is no current research into the effects of apex predator loss in these ecosystems. The African thicket ecosystem should be used as a model for future studies into dual-apex interactions, as exploration of connections in this novel system was valuable. As briefly  outlined, complex multi-directional trophic cascades have not been widely recognised and described. If we are to gain valuable insight into the impacts of apex predator loss, we must research this area further, in different dual-apex systems, as currently little is known about the consequences of apex predator declines. Equally, the role of consumer control in structuring ecosystems is not widely recognised5. This further highlights the need to consider the effects of apex predator loss in ecosystems globally, and the importance of preserving all types of apex consumers in an increasingly downgraded world.

References

  1. Tambling CJ et al. (2013) Basic and Applied Ecology 14, 694-701.
  2. Slotow R, & van Dyk G. (2001) Koedoe 44, 85-94.
  3. Bauer H et al. (2012) Panthera leo: The IUCN Red List of Threatened Species. (available at www.iucnredlist.org). Updated 2014 (Accessed 01 December 2014).
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