On The Path Of The Prey Of The Pangolin
Do seasonal dietary shifts by Temminck’s pangolins compensate for winter resource scarcity in a semi-arid environment? (2022) Panaino et al., Journal of Arid Environments, https://doi.org/10.1016/j.jaridenv.2021.104676
Climate change and habitat destruction are never positives for any species, but if that species is adaptable, they might be able to tolerate such hazards. Finding food in changing environments is one of the big challenges for a species, and there are a few things that species can do to adapt their diets when new conditions emerge. They can try and find more energy-rich food, or they could spend more time foraging to increase their energy intake (though this could also cost them more energy as well).
This is a particular problem for species which live in dry, arid environments, where food can already be scarce. In many environments vegetation and all the animal life that comes with it will often increase with temperature, but in an area that is already hot, at a certain point an increase in temperature will result in lots of vegetation dying off.
Today’s researchers selected a particularly charismatic species, the Temminck’s pangolin, and through some truly admirable fieldwork, monitored whether or not their foraging activities changed as the environment varied.
What They Did
The team monitored six pangolins in the Kalahari Reserive in South Africa over a three year period. They tagged and then tracked the pangolins, often observing them feeding, as well as collecting pangolin faeces. They were also able to monitor how long pangolins were active for by taking temperature readings through the tags!
In addition to the pangolins, they also monitored how the local vegetation changed with the weather, and how the abundance of common pangolin prey (small insects like ants and termites) changed during the study. to see how they were related to a) the surrounding temperature and b) the pangolins’ foraging activities. Vegetation was measured by setting up 50 metre transects throughout the region and monitoring changes in vegetation on a monthly basis, and prey abundance was measured by counting the numbers of different insects that fell into pitfall traps.
Did You Know: Illegal Pangolin Trade
The illegal trafficking of pangolins for their scales has seen a massive explosion over the las ten years. As reported by ScienceDaily, “shipments intercepted and reported by authorities between 2010 and September 2021 amounted to 190,407 kilos of pangolin scales taken from at least 799,343 but potentially up to almost a million dead creatures”. There are eight species of pangolin worldwide, and they’re all listed as endangered.
What They Found
The abundance of the pangolins’ prey did increase, but only until the temperature hit 27 degrees celsius, after which point it started to drop. Yet prey abundance did not seem to influence the energy intake of the pangolins. Instead, the energy intake of the pangolins was only increased by increased levels of time above ground – the more time the pangolins spent above ground, the higher the energy intake.
Pangolins also didn’t seem to increase the diversity of their prey in any predictable manner. The researchers had thought that they may increase their prey diversity as prey got more scarce, yet prey diversity only increased notably at one point during the study, and it wasn’t at a point where prey abundance was particularly low.
This is of course a very localised, low numbers study. But it’s not something that can really be faulted, especially given the extensive fieldwork that went into the data collection. Yet one important point the authors note is that the heat seen during the summers in which the study occurred weren’t as extreme as summers which have occurred beforehand, and which will no doubt occur in the future. Whether or not prey intake and abundance follow similar patterns in more extreme years could be a different matter.
For some weird reason I love reading papers in which the results don’t match the expectations. It’s a credit to the scientists that they were able to still make a great contribution to our understanding of how species adapt to changing environments, even when they don’t react the way we would expect.
From the pangolins’ perspective, it’s a little worrying. It indicates a lack of adaptation to a drop in prey abundance, which could spell trouble for them in the future. Hopefully this pattern isn’t indicative of a larger scale problem throughout the whole species!
Dr. Sam Perrin is a freshwater ecologist who completed his PhD at the Norwegian University of Science and Technology and really adores how nervous pangolins constantly look and wants to provide them with free self-help books. You can read more about his research and the rest of the Ecology for the Masses writers here, see more of his work at Ecology for the Masses here, or follow him on Twitter here.