Above: Spotted Towhee (Photo by Jim Bass)
By Laura and Hal Mahan
Nearly every week we are asked about why birds do seemingly unusual or senseless things. For example, why do they fly into windows? Often we think a bird sees the reflection of trees in the glass without seeing the glass itself, and then accidentally flies into the window.
Sometimes, though, the answer is more complicated, and the question becomes, why does that male cardinal fly into the window, over and over and over on purpose? The answer to this lies in the complex territoriality behavior that many birds exhibit during nesting season. It sees a reflection of itself and its overriding instinct is to scare away its “competitor.”
Lately, we have been observing an American Robin behind our store building where we park our cars every day. We would probably not have paid a huge amount of attention to this bird, except that all of our cars have been bombed with white bird droppings around the side-view mirrors. Finally, some us had the idea to hang black plastic trash bags out the car windows and draped over the mirrors in order to hide them and hopefully give this poor robin some peace.
Even though we are sometimes aggravated at the “white wash” on our cars, we are fascinated by all aspects of bird behavior, and it became one of the fields that author Hal Mahan became quite expert in during his days as a college professor.
The “simple” act of nest-building is one of the most interesting aspects of bird behavior. Have you ever considered why it is that American Robin nests mostly all look alike, and Northern Cardinal nests look the same, etc., etc.? But if you compare nests of different kinds of birds, they have distinctly different shapes, are made of distinctly different materials, and are placed in different situations in the bird’s habitat.
For example, there is a group of closely related birds which occur here in the eastern U.S. including Asheville, called the tyrant flycatchers. In this group are such common local species as the Eastern Kingbird, Eastern Phoebe, and Great Crested Flycatcher. The kingbird and phoebe build nests on a tree branch, or perhaps on a ledge of a building or bridge. The Great Crested Flycatcher, however, builds its nest inside of a natural cavity like a hole in a tree, or in a bird house that you place in your yard.
Strangely, the Great Crested Flycatcher usually incorporates a shed snake skin into its nesting material and sometimes hanging on the outside of the nesting cavity. Why? Studies have shown that it is an effective warning to prevent mammals such as flying squirrels from raiding the nest. How clever!
Why do such closely-related birds exhibit such contrasts in behavior? It is fascinating to observe, and fascinating to learn about! This month Dr. Hal Mahan will be presenting a program about the mysteries of bird behavior. For details, visit compleatnaturalist.com.
Laura and Hal Mahan are owners of The Compleat Naturalist, located at 2 Brook Street in the Historic Biltmore Village. To learn more, visit compleatnaturalist.com or call 828.274.5430.
