Nancy Collins

When a bird sings, we usually hear something that’s calming, pleasant and melodious. However, a bird doesn’t really care. He just cares if his message gets through.

The two main reasons a bird sings are defining its territory and attracting a mate.

Singing is directed only at members of the bird’s own species. Each species has a different song (or songs), and individual birds of the same species sound pretty much alike. However, there is often a slight variation between different populations of the same species; sort of like listening to a New Englander or someone from Alabama speak English.

In general, it’s the male bird that sings, although the female of some species can also sing. The reason is common sense; the males want to draw attention to themselves, whereas females want to remain hidden, since they are often in the vulnerable position of incubating eggs or caring for young. Also, almost all birds have two “voice boxes,” so they can sing intricate and complex songs that you and I do a terrible job of imitating.

Most bird songs establish the singer’s territory. It is within this territory that a pair of birds will get the bulk of their food, hunt for nest material, raise their young and so on - so a well-chosen territory must be aggressively guarded from rivals.

The relative size of a territory varies greatly. It depends on the amount of food, shelter and nesting material it contains.

Special attractions that all birds need, like feeders, nesting areas and birdbaths, seem to be excluded from the exclusive territory of just one bird. They’re out of bounds or “neutral territory,” which all birds can visit with only minimal annoyances from other birds.

A bird’s song means nothing to birds of a different species. The other bird probably has different food and nesting requirements, so different species often live in the same area, ignoring the songs of other species. Within a given territory it’s possible to have a robin, a cardinal, a chickadee, a mockingbird and bluebird, all nesting without interfering with each other’s needs. One species eats seeds, another eats insects. One species nests in tree cavities, another may build a nest on the ground, and so on.

 To establish a territory, the male chooses a series of song posts from which to sing (specific trees, fence posts and such). By singing from each of them regularly, he lays claim to and defines his territory. The borders are invisible, of course, but if a rival male crosses into an occupied territory he will be instantly challenged. Some birds have several songs, and may use a different one at each song post.

This could create the illusion of a number of occupied territories, and be more successful in keeping intruders away.

When a male challenges, the ensuing fights or chases may sometimes involve aggressive bursts of song meant to scare the intruder.

The territory’s original “owner” almost always emerges as the winner of such disputes

Another use for bird song is to advertise to a female that an unattached male is present, offering the females a home. He’s announcing his status and virility (some call this the “shiny sports car” syndrome). It follows, then, that the male who is already paired up will tend to sing less, using his song purely for protecting its territory.

The female, however, is thought to be able to distinguish between the songs of a bachelor bird and one that is paired. Singing also serves to strengthen the bond between a pair.

Some birds also have a sub-song. It’s usually a quieter and lower version of their normal song. It doesn’t carry very far and is usually only heard in fall and spring. Some sub-songs are almost certainly rendered by young birds, so it could be thought of as a kind of practicing.

Bird calls are different from songs. They are quite short, simple sounds and so have only one or two syllables. Calls communicate totally different messages from songs — such as signaling that a predator is near, showing aggression, calling young birds home or contacting birds of the same species.

Whatever sound the bird makes, it typically sounds pleasant and sweet to us. But to other birds it may mean “get out of my territory” or “I can help raise healthy nestlings” or “watch out for that human over there.”

NANCY COLLINS is a Denton resident, a Master Naturalist and co-owner of Denton’s Wild Bird Center. She is a member of the International Wildlife Rehabilitation Council, National Wildlife Federation, the National Wildlife Rehabilitators Association and Native Plant Society of Texas. She can be reached by calling 940-484-BIRD (2473) or by e-mailing denton@wildbird.com .