Elk are primarily herbivores mainly eating grasses, sedge, and shrubs but they are opportunistic when it comes to obtaining calories and there have been rare observations of elk eating other animals like snakes and rodents.
Elk preying on small animals is an extremely uncommon behavior but there have been multiple accounts in North America of elk chasing, killing, and partially eating goslings, often despite strong defensive efforts from adult geese.
The following video shows one such case of an elk actively hunting a group of goslings. The mother goose made a valiant effort defending her young and took a short flight path to strike the elk in the face, momentarily distracting it from its prey but the elk eventually separated one of the goslings from the flock and consumed it:
“Nature is crazy. This video shows the determination of both species when prey becomes predator. Eventually the cow elk was able to get one gosling separated and ate it.”
Here is another instance of an elk eating a gosling from the same photographer who operates in Rocky Mountain National Park, Estes Park, and surrounding areas.
