Herds
Herd of cows. Photo courtesy of www.texaslonghorn.net/main.cfm
JB: This is Earth and Sky with a question from a listener. Hillarie Grant, of Fairfield, California, wants to know, “How do herds form?”
DB: Many animals display herding – or group-forming – behavior . There are three main ideas as to why. Protection from predators is probably the main reason. With more bodies, there are more eyes to watch for danger. In one reliable experiment, ostriches kept their heads up more in smaller groups. It seems that the bigger the group, the safer it is for the birds to put their heads down and eat. What’s more, the chance that any individual will be eaten diminishes as the group size grows.
JB: Being in a group can also make it easier to find food, either through cooperation or by observing where other animals go. And animals might also form groups when a limited amount of food or good living space is available. But sociability has its downside, too. Animals living too close together are more susceptible to parasites and disease. Likewise, bigger groups bring more competition for resources within the group.
DB: Meanwhile, scientists still don’t know why animals like penguins, ground squirrels and wolves are so social – while others like cats and polar bears tend to be more solitary. For more about herding come to earthsky.org. Thanks today to the a href=“http://www.fws.gov/”>U. S. Fish and Wildlife Service and to the National Fish and Wildlife Foundation. We’re Block and Byrd for Earth and Sky.
The following people were interviewed for today’s program. Our thanks to:
Charles R. Brown
Professor
Editor
Journal of Field Ornithology
Associate Editor
Behavioral Ecology and Sociobiology
Department of Biological Sciences
University of Tulsa
Tulsa, OK
Alan Kamil
Professor
School of Biological Sciences
University of Nebraska
Lincoln, NE
Link
For more info on animal group names, visit here (EnchantedLearning.com)
Author’s Notes
Social behavior in animals is such an intricate and imprecise science that behavioral scientists stuff journals full of research about it every year.
One big question is what actually motivates an individual to join a group, considering some of the real risks involved in group-living.
In some cases, animals live with family members. By cooperating with relatives, they increase the chances that some of their own genes will get passed to the next generation. In groups of non-related individuals, the motivation to congregate might be more selfish.
“Imagine a circular pond with a set of frogs on the edge,” says Alan Kamil, a biologist at the University of Nebraska in Lincoln. “Now imagine that every once in a while, a predator pops up, grabs, and eats the closest frog. How should the frogs behave? Selfish frogs would try to get as close to other frogs as possible, preferably between two frogs. You end up with a herd of frogs, each of which is behaving selfishly.”
Even among social animals, groups are fluid structures. In swallows, young birds are more likely to prefer groups than are older individuals. Packs of prairie dogs are made up mostly of female relatives, while the males come and go. Some solitary animals tend to group up more when predators are around or during breeding seasons. Then, for reasons scientists are still trying to figure out, everything can change.
In many ways, grouping behavior in animals mirrors sociability in people. There are lots of good reasons to live in a city. But sometimes, you just need to get away from it all!
Additional Teacher Resources
Craig Reynolds, Boids (Flocks, Herds, and Schools: A Distributed Behavioral Model.): Boids
This site consists of a computer model of coordinated animal motion such as bird flocks, animal herds, and fish schools. Also available is a wealth of in-depth information into a variety of facets concerning the social and physical science behind flocks, herds and schools. This site is geared more to older students.
EnchantedLearning.com.: Herds and Packs of Dinosaurs
This site explains how fossil evidence suggests that certain dinosaurs used to live in herds or packs. It explains that most likely this was due to safety in numbers or better success in hunting. The article provides a good introduction to the behavioral reasons behind herds to younger children using a subject they will respond to?dinosaurs.
