Can camera traps placed in trees offer a way to rapidly inventory secretive arboreal mammals? How does this approach compare with traditional survey techniques? Dr Andy Whitworth and his colleagues set out to answer these questions for the first time in their recent publication in Tropical Conservation Science. We spoke with Andy to find out more about his experiences pushing the boundaries of camera trapping.
Q: What challenge has this technology helped you overcome?
Surveying rainforest mammals is a difficult task, even for terrestrial species… for the arboreal species it is a nightmare! Trying to study mammals which could be well over 30m above you is a challenge in the day time, and near impossible at night. We wanted to bring the advantages camera traps brought to the study of terrestrial mammals to those that live in the canopy, and given the recent improvements in canopy access climbing techniques and safety it became a reality! We are now using these camera traps in the rainforest canopy to gather information on species and communities that we previously knew very little about.
Q: How did you first get the idea to use this technology for your work?
Honestly, I would love to claim the idea myself, but in 2009 I had a colleague working with me in Ecuador whom suggested putting a camera in the trees to detect an elusive group of Howler monkeys which we were struggling to find in degraded habitat. I laughed as we had no climbing equipment back then and gradually forgot about the idea. I moved to Peru in 2011, and the idea came back to me when I got the opportunity to attend a training course in tree climbing. Armed with just 20 cameras we set out to trial the project in 2012. It worked surprisingly well! Other researchers had similar ideas around the same time, and a number of publications including one ground-breaking paper by Tremaine Gregory (2014) which assessed mammal activity over natural bridges over an oil pipeline.
Q: Do you use specific criteria to select the technology or model you use?
Prior to trialling camera trapping in the canopy I had been using the Bushnell Natureview/Trophycam models on the ground for a number of years; with great success. They were just as successful in the trees. Every year the quality of photos and videos improves, battery life is impressive and they are nice and compact. So I haven’t really tried other models as I have been so happy with Bushnell!
Q: What were some of the biggest challenges you faced using this technology in your location?
It is easy to attend a training course in the UK or US and learn to climb a tree in temperate forest, but when you get to a tropical forest things get a lot more complicated. Anyone looking to use this technique straight after completing a training course should factor in plenty of time practice firing lines into the canopy, initially it can be one of the most time consuming parts of the methodology. Tropical environments can be both difficult and dangerous, the tree diversity is mind boggling and there is plenty of flora and fauna out there looking to ruin your day! I was trained though Canopy Access Ltd in the UK - James Aldred and his trainers have invaluable experience in range of different ecosystems and I strongly recommend them to get expert training. Identification of trees once in the field is very tough and expert local knowledgeis essential to both identifying healthy hardwood species and avoid any potentially weaker tree species that could collapse under your weight. An experienced team is important as there is NO room to make mistakes when in the rainforest canopy. It also takes time to learning how to effectively place the cameras in the trees - choosing both suitable AND safely accessible locations is not easy.
Q: What are some of the shortcomings of the technology you’re using for your work that you’d like to see addressed?
Right now there is a real placement bias, as mentioned above, to accessible and safe to reach places. Arboreal animals might not necessarily use such areas and I think improved access techniques or even the development of camera setups that can be coordinated from the ground, without the climb the tree beforehand, could be developed. It is also difficult to assess group size from a single direction camera. Multiple cameras or wider camera with wider fields of view (maybe 360o) could go some way to tackling this. As we are at the very early stages of using camera in the trees, we are not yet certain about the appropriate analytical techniques (e.g. for estimation of population densities). I know some researchers are addressing some of these questions right now, as it isn’t safe to assume that the analytical methods developed for terrestrial cameras will directly translate into analysis of data from the canopy.
Q: Have there been any unexpected positives for using this technology? What are the most surprising findings that the technology has helped you to discover?
I think we were really hoping the cameras might detect secretive species like pygmy anteater and arboreal porcupines, but didn’t really to get success with large eagles (harpy and crested) or rare canopy dwelling lizards! Also, the success in detecting hunted species where human observers had missed them was very cool.
Q: What advice would you give other groups such as yours that might be thinking about using this technology in their work?
As I said, get great training and advice from experts and other people already doing this! There are so many uses to explore, temperate forest environments, different strata, habitat disturbance, forest regeneration, connectivity of the environment, the importance of different forest features (such as shrubs, vines & lianas, emergent trees, etc) and so many questions about behaviour and potentially even new species to discover!
Find out more
The full publication is open-acess and available to read on demand. Read it to find out more about the species-specific effectiveness of arboreal camera traps and a cost comparison of the different methodologies for monitoring cryptic arboreal mammals.
Whitworth, A., Braunholtz, A.D., Huarcaya, R.P., MacLeod, R., & Beirne, C. (2016). Out on a limb: arboreal camera traps as an emerging methodology for inventorying elusive rainforest mammals. Tropical Conservation Science Vol. 9 (2): 675-698.
About the Author
Dr Andrew Whitworth (@andy_manu_peru) works with the Crees Foundation and the Unviersity of Glasgow. His research is based around the value of regenerating tropical forests and their potential importance for future levels of biodiversity. The research looks particularly at richness, abundance and diversity levels of birds, mammals, butterflies, amphibians and reptiles within forests of different disturbance histories. He is also interested how current hunting/logging pressures can affect the distribution and movement patterns of mammals and game birds. Predator-prey interactions within regenerating forest are also considered in terms of temporal and spatial patterns, with a further focus on how different predators (Jaguar, Puma and Ocelot) share the habitat.
Thanks to Dr Chris Beirne (@Chris_Beirne) for edits and comments.
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