Unexpected Items in the Diet of the White-Tail Deer

I remember my 7th grade biology teacher arguing with a student who insisted her family’s cow ate their chickens.  Mr. Amick assured her that a cow was an herbivore and would never eat meat, but the farm girl adamently asserted what she had witnessed.  I thought of this argument 20 years later when I read an article in Natural History magazine about how red deer living on an island ate sea bird nestlings.  Scientists concluded the deer ate the birds because the plants growing on the island were deficient of calcium, and the deer obtained this nutrient from the bird bones.

White-tail deer scavenging a rabbit.

It’s not at all unusual for deer to eat meat protein. White-tail deer have been recorded eating injured birds, bird nestlings, quail eggs, carrion (especially dead fish), and insects. The following link to a youtube video shows a deer eating a young bird before it had learned how to fly.  http://www.youtube.com/watch?feature=player_detailpage&v=sQOQdBLHrLk

Alewives frequently wash up on the shores of Lake Michigan, and one scientific study found they made for a common item in the deer’s diet there.  But this isn’t an isolated localized behavior.  Deer have been observed eating fish on the sea shores and along Florida’s lakes.

Like cows, deer have 4-chambered stomachs, and they chew their cud.  Plant material is more difficult to digest than meat, but meat protein probably passes through a deer’s stomach without requiring further chewing.  Imagine how nasty cud mixed with dead fish would be.

During the Eocene, ungulates arose from a common ancestor shared with carnivores, so it shouldn’t be a surprise that they’ll enjoy a meal of meat when they can get it.  But they’ve become specialized toward a primarily herbivore niche and can no longer actively stalk and catch most prey.  Hogs are among the most primitive of ungulates and are well known for being omnivorous.  One Eocene age species of pig, the enteledont, is believed to have rammed and killed other animals.  Despite being an ungulate, it was one of the top predators of its time.

The ability to exploit many different foods improves the survival rate of white-tail deer.  In a forested environment it’s the omnivores that are the most abundant large animals. Instead of a sea of grass, there is a wider variety of foods.  In late Pleistocene Georgia the 3 most common large mammal species were white-tail deer, long-nosed peccary, and black bears.  Even during arid stadials when grassland habitat expanded, forests were still the most common ecotype in this state.  Being able to eat a wider variety of foods allowed these 3 to dominate the faunal assemblage in terms of sheer numbers.  Today, because forest is still the predominant ecosystem here, deer and hog are prevalent in large numbers and bears would be too, if humans could tolerate more of them.

Mylohyus nasatus–the long-nosed peccary.  They were almost as common as deer in Georgia during the Pleistocene.  If I could live in eastern Georgia 36,000 years ago (as I occasionally fantasize about in my irregular series “If I could live in the Pleistocene”), I would expect this species along with deer and bear to be the most abundant large animals, especially since this time period was an interstadial with warmer temperatures and more precipitation than the stadials, and therefore more forests than grasslands.

Black bears (Ursus americanus) were also very common during the late Pleistocene.  The short-faced bears were more abundant in the early Pleistocene, but they were specialists with 2 species more carnivorous and 1 more herbivorous than black bears.  The generalized diet of black bears evidentally helped them become more successful toward the end of the Pleistocene than the short-faced bears and perhaps explains how they survived the megafauna extinction.