Jackson Hole EcoTour Wildlife Adventures | Species Profile: Grand Teton Bison
You may have heard the story of the Brown-headed Cowbird evolving its habit of "nest parasitism," due to the bison, wandering the prairies. The brown-headed cowbird (Molothrus ater) is a brood parasite that lays its eggs in the nests of other birds. These "foster parents", called hosts. Cowbirds and bison have a commensal relationship in which the cowbirds benefit from the activities of the bison and the bison is neither helped nor harmed by.
Taylor Phillips Bison herds are led by dominant matriarchs, with large bulls often forming separate bachelor groups.Bird Watching a Tame Wild Cowbird
They frequently make and use bison wallows, which are large bare patches of compacted soil the bison use to scent mark and perhaps rid themselves of pests. Trees in high traffic areas are also subject to rubbing and become polished smooth. Bison can travel at 35 miles per hour and though they look docile are the most dangerous animal in the parks, having gored five people last summer.
- Cowbird and Bison
It is easy to avoid an altercation however by giving bison space and not approaching them. Herbivores are important nutrient cyclers; their digestive system acts as a decomposer, fertilizing prairie soils with manure.
Species Profile : Bison
This is a critical benefit in an area where decomposition is so slow that trees burned by the Yellowstone fires are still standing. As they graze in grassland areas like the Hayden Valley, bison herds are followed by brown headed cowbirds, who feed off of insects attracted to the bison or stirred up by their movements. Using a strategy known as brood parasitism, they lay eggs in other birds nests. Cowbird chicks are then raised by surrogate parents who are often much smaller then they are!
This article by Audubon explains how cowbirds go about learning to be cowbirds without their biological parents.
Widespread across the U. Eventually little was left but bleached bones, which were then collected to be shipped east for fertilizer. The exhibit, titled Monarchs of the Plains, runs through May 8th. The Lamar Bison Ranch was born. Today bison in Yellowstone number over animals, with animals increasingly being moved to reestablish wild herds elsewhere in the country.
Twice the trail ran right through the center of prairie dog towns. Their alarm calls were incessant and pushed before me in a wave, with the closest little rodents chattering from out of sight inside the entrance to their burrow.
The bell-like tones of meadowlark calls rang out across the prairie, and repeatedly I searched for the vocalists who sounded much closer than their actual perch. The volume of their songs was impressive. Back at my car, I quickly settled in for an afternoon of driving west.
Brown headed cowbirds and bison
Pa Ingalls would have understood the feeling. Where the park road met the highway, a pair of bison grazed on the shoulder. If it was just those two great, shaggy beasts, I might not have stopped, but around their heads fluttered personal flocks of brown-headed cowbirds. Glad that no one was with me to roll their eyes at my excitement, I swung onto the shoulder, rolled down a window, and picked up my camera from the passenger seat.
Now, brown-headed cowbirds are not my favorite animals. My parents and naturalist friends have always given them the evil eye.
Female brown-headed cowbirds lay their eggs in the nests of smaller birds and let other parents do the hard work of feeding their hungry chicks. Cowbird eggs hatch first, and their chicks grow faster than the others.
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By virtue of being the tallest mouth in the nest, the cowbird babies get more food. House wrens puncture cowbird eggs. Yellow build a new nest right on top of the invaded one—smothering their own eggs as well.
Robins, catbirds, and a few other birds with big beaks toss out the strange eggs. I feel like giving them all a high-five for not being duped.
The problem was that bison herds moved regularly, and the birds had to follow. A female cowbird lays about one thick-shelled egg each morning, and can lay forty or even sixty eggs in a season.