A new paper published by Dr Andrew Whitworth (and colleagues), Project Leader of Tree Top Manu, demonstrates how arboreal camera-trapping can answer questions about secretive and cryptic species in a way that traditional ground-based surveying methods cannot.
Camera traps are triggered by infra-red sensors, taking photographs and videos of wildlife 24 hours a day. They’re used by researchers to gain ecological, behavioural, abundance and diversity information on rare and elusive species. To-date camera traps have mostly been placed at ground level, greatly limiting their capability of recording life in the three-dimensional space of a tropical forest.
Andrew and his colleagues launched the Tree Top Manu project in 2012 to use terrestrial and arboreal camera traps. The aim: to begin filling in the knowledge gap on arboreal mammals in the Manu Biosphere Reserve, a UNESCO World Heritage Site that’s one of the most biodiverse places on Earth. It’s the largest-scale canopy monitoring project in the world and is led by the Crees Foundation in collaboration with Glasgow University.
The new paper, entitled Out on a limb: Arboreal camera traps as an emerging methodology for inventorying elusive rainforest mammals, is the first time that an assessment of the effectiveness of arboreal camera traps has been compared with results from other surveying methods.
Improving our understanding of arboreal species is crucial as information about their ecology and distribution often remains sparse due to secretive, cryptic and nocturnal activity that makes them difficult to survey.
“The arboreal camera trap methodology can be used to provide accurate inventories of mammal communities in the trees”, said Andrew. “It’s unbelievably difficult to monitor rainforest mammals using traditional methods. People have been using camera traps for years now, a couple of decades, to monitor terrestrial species because they’re really secretive. So why not use them for the arboreal ones? We’ve just decided to ignore them.”
The data from this new paper is based on 2014 records and the results find that arboreal camera traps are particularly useful in the detection of larger, hunted species of high conservation concern, such as the black-faced spider monkey and Peruvian woolly monkey, both categorised as Endangered on the IUCN Red List of Threatened Species.
Arboreal camera traps also prove effective in detecting lesser-known, cryptic species like the bicolour-spined porcupine and silky pygmy anteater. Although recorded from a number of locations throughout Amazonia, detailed information about the ecology and distribution of both species is limited.
“The big discovery for me”, said Andrew, “was that the silky pygmy anteater exists here at the MLC reserve. There have been people working at the MLC for over 10 years doing research and no-one has ever recorded this anteater – in over 10 years! We had those camera traps out for three months and we had two videos of silky pygmy anteater. I couldn’t believe it when we brought the cameras in. Adding a new mammal to the species list in a place that’s had over 10 years of research is quite incredible. It shows the power of camera traps in the trees as a research methodology.”
Despite the benefits of arboreal camera traps, one of the concerns for cash-strapped conservation scientists is the upfront investment needed to cover training and equipment costs. Although there is an initial expense, the paper’s cost-effort analysis shows that overall costs are similar to traditional surveying, if you take into account the additional survey hours that would be needed to provide similar numbers of records using ground-based methods.
“Some people may be a bit sceptical or frightened away by the cost of arboreal camera trapping”, said Andrew, “but what we found is that the cost actually balances in the long term. So for researchers who are studying mammals continually, it could be well worth the investment.”
There are advantages and limitations with every methodology and the paper provides researchers with recommendations for the most useful and cost-effective way of studying arboreal mammals under different circumstances.
Camera traps in the canopy can shine a light on some of the most charismatic and threatened species in the world. Without them, some secretive and cryptic mammals risk remaining largely unknown and could quietly disappear from our planet.