![]() Cougar presence was defined by noting cougar kills, cougar trails, or direct evidence from camera traps. Then, they related the activity of the donkeys to the presence or absence of cougars. First, they quantified the temporal activity of both donkeys and cougars, noting when and where each species was active. Luckily, cougars are protected from hunting in this area, making it easier to relate their presence to any effects on donkeys. The authors conducted an observational study in Death Valley National Park, an area home to both feral donkeys and cougars. ![]() Because the deer stopped eating some of the vegetation, erosion was limited, which stabilized riverbanks, which eventually changed the course of the river itself! What They Did When the wolves came back to the park, their deer prey began avoiding areas where the wolves were active. The most famous example of this was the reintroduction of wolves to Yellowstone National Park in the USA. A trophic cascade is when an organisms at the upper or lower parts of a food web causes an effect that cascades downwards or upwards to affect the other organisms in the food web. We’ve mentioned them before on Ecology for the Masses, but because trophic cascades are such an important part of today’s study it is worth coming back to them. Today’s authors report on a novel trophic cascade between the cougar, feral donkeys ( Equus africanus asinus), and wetland vegetation. Specifically, some reports state that these species don’t have any natural predators, and other reports echo the claim. ![]() In the United States, large felines such as cougars ( Puma concolor) are known to predate large equid species (such as feral horses or donkeys), but much of the ecological literature assumes/claims that cougars do no exert a strong enough pressure to consider them “significant” predators of these equid species. Though large predators were lost, many large herbivores are still around, which means it is difficult for a smaller predator to take down/consume these herbivores, much less have an effect large enough to drive a trophic cascade. ![]() However, most of the world’s large predator species were lost around 10,000 years ago (potentially due to human impacts), thus limiting the role that predators could play in driving trophic cascades. Trophic cascades (see Did You Know?) are an important part of many ecological systems. Image credit: CHUCAO, CC BY-SA 3.0, via Wikimedia Commons The Crux A novel trophic cascade between cougars and feral donkeys shapes desert wetlands (2022) Lundgren et al., Journal of Animal Ecology, ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |