Imagine a healthy forest, home to a variety of species: Birds are flitting between tree branches, salamanders are sliding through leaf litter, and wolves are tracking the scent of deer through the understory. Each of these animals has a role in the forest, and most ecologists would argue that losing any one of these species would be bad for the ecosystem as a whole.
Unfortunately – whether due to habitat loss, overhunting or introduced species – humans have made some species disappear. At the same time, other species have adapted to us and spread more widely.
As an ecologist, I’m curious about what these changes mean for ecosystems – can these newly arrived species functionally replace the species that used to be there? I studied this process in eastern North America, where some top predators have disappeared and a new predator has arrived.
A primer on predators
Wolves used to roam across every state east of the Mississippi River. But as the land was developed, many people viewed wolves as threats and wiped most of them out. These days, a mix of gray wolves and eastern wolves persist in Canada and around the Great Lakes, which I collectively refer to as northeastern wolves. There’s also a small population of red wolves – a distinct and smaller species of wolf – on the coast of North Carolina.
The disappearance of wolves may have given coyotes the opportunity they needed. Starting around 1900, coyotes began expanding their range east and have now colonized nearly all of eastern North America.
Coyotes colonized most of eastern North America in the wake of wolf extirpation.
Jensen 2025, CC BY
So are coyotes the new wolf? Can they fill the same ecological role that wolves used to? These are the questions I set out to answer in my paper published in August 2025 in the Stacks Journal. I focused on their role as predators – what they eat and how often they kill big herbivores, such as deer and moose.
What’s on the menu?
I started by reviewing every paper I could find on wolf or coyote diets, recording what percent of scat or stomach samples contained common food items such as deer, rabbits, small rodents or fruit. I compared northeastern wolf diets to northeastern coyote diets and red wolf diets to southeastern coyote diets.
I found two striking differences between wolf and coyote diets. First, wolves ate more medium-sized herbivores. In particular, they ate more beavers in the northeast and more nutria in the southeast. Both of these species are large aquatic rodents that influence ecosystems – beaver dam building changes how water moves, sometimes undesirably for land owners, while nutria are non-native and damaging to wetlands.
Second, wolves have narrower diets overall. They eat less fruit and fewer omnivores such as birds, raccoons and foxes, compared to coyotes. This means that coyotes are likely performing some ecological roles that wolves never did, such as dispersing…
