HOW DOES A bird know it is a particular species? The quick and easy answer is “instinct.”
There is a bit more to it than that, even though instinct governs many of a bird’s actions, migration being one of them. All creatures are attracted to others who resemble them, and when it comes to baby birds, that attraction is referred to as “imprinting.”
When a baby bird breaks free of its shell, it imprints on the first being it sees. Robin babies are fed by robin parents, and that tells the infant it is a robin.
It will choose another robin for a mate. It will argue with other robins that trespass on its territory during the nesting season. In the fall, it will flock together with other robins to seek out the food attractive to robins.
This imprinting works well for the majority of bird species, but there are some exceptions. It’s not only important to know you are a robin, a jay or a sparrow; you must know if others of your kind are male or female.
Male and female robins do not look exactly alike. There is just enough difference in the intensity of their coloring to make telling them apart possible.
Most of the time, the male and female of any passerine bird looks noticeably different from one another. Sometimes the difference is very subtle, but not if you are a bird.
Even a bird can make a mistake, especially if both sexes appear identical — like song sparrows. I can’t remember where I read about song sparrows when it comes to spring courtship, but I’ll never forget what was written on their problem with recognizing the opposite sex during spring mating season.
The writer related that the best way to tell males and females apart was to observe how two song sparrows reacted to one another.
When a song sparrow comes face to face with another song sparrow, each sex reacts differently.
A male bird ruffles his feathers and attempts to chase away what looks like another male in the area. If that bird is a male, it will assume an equally aggressive demeanor. He who bluffs the best will take the day.
When a female song sparrow is accosted by such a male, she will effect a submissive attitude complete with pitiful peeping while assuming the pleading manner of a young bird begging from an adult.
That changes the aggressive male’s manner. He realizes he has made a mistake and must change from an aggressor to an admirer. If he offers her a tidbit and she accepts it, the two just might connect.
The imprinting that takes place when a bird is newly hatched is strong enough to create real problems if the bird isn’t properly imprinted. For example, should the bird see another bird, even another being, it will still imprint on them.
Cowbirds lay their eggs in the nests of other birds. When a tiny yellow warbler discovers one of her offspring is a much larger cowbird, she will still be faced with feeding the begging giant who faithfully follows its step-parent about.
It thinks it’s a yellow warbler. The warbler may suspect otherwise but is programmed to put food in that open, begging mouth.
Should a hatchling spot a human being when it pops out of its shell, it still sees Mom or Dad. This is a problem when eggs are being hatched in a lab where conservation efforts are trying to increase an endangered species population.
Those working with whooping cranes or California condors wear costumes resembling the bird’s natural parents. The human is mostly concealed and their arm and hand are meant to look like a parent arriving with food.
The arrangement resembles a hand puppet and it has been successful. Both the cranes and the condors are success stories and imprinting played a major role. It always does.
Joan Carson’s column appears every Sunday. Contact her at P.O. Box 532, Poulsbo, WA 98370, with a self-addressed, stamped envelope for a reply. Email: [email protected]