One moonlit April night, I woke long before dawn, groggily wondering what had jerked me from sleep. I listened to Richard's breathing next to me, and heard Molly mutter in her sleep in the next room. Then, from above on the roof, I heard loud singing:   first the long bubbling song of a thrasher, repeated several times, then a bit of improvisation, followed by a slick imitation of our neighbor's car alarm. I drifted back to sleep as the songster launched without a pause into a black-throated sparrow's sweet trill.

My nighttime serenader was a northern mockingbird, Mimus polyglottos, "many-tongued mimic" in Latin. Male mockingbirds are among the world's most accomplished vocal copyists. Their long musical solos borrow songs and calls from as many as 50 other bird species, and also sounds from other animals:  frogs peeping, crickets chirping, the barking of dogs. Mockingbird's songs even include mechanical noises such as the squeak of a wheelbarrow, sirens, or car alarms. They mimic so well that electronic analysis of the mockingbird's "copy" shows no difference from the original.

Male mockingbirds exercise their vocal artistry most during the early spring and summer mating seasons. They sing for reasons similar to those which motivate human males to cruise city streets:  to advertise their maleness, attract mates, discourage competitors, and to delineate their territories. The more extensive his vocal repertoi

re, the better chance a male mockingbird has of mimicking and driving away other birds, thereby gaining a larger share of habitat, and more access to the female listening audience. The songsters pick high perches - television antennas, utility poles, or tall cacti, shrubs, or trees - to better broadcast their signals. Unmated males sometimes sing all night long!

Male mockingbirds also defend their territories with body language:  two males may confront each other at a territorial boundary and "dance," rapidly hopping sideways, flashing their black and white wings, flicking their long tails, like boxers sparring for an opening. But the pair never actually spars; the name of the game is to intimidate, not to injure.

I treasure the presence of these slender, robin-sized, grey and white birds in my suburban neighborhood - even when the hormone-driven singers wake me at night. Mockingbirds - year round residents of the southern United States and northern Mexico - are one of the few native birds to adapt well to both the desert, and to urban lawn and shade tree habitat. Mockingbirds energetically search lawns and other open areas for insects and other small arthropods, helping keep "pest" populations under control. They also devour berries and fruits, especially red fruits, like fiery chiltepines, native chile peppers.

Unfortunately, human habitat can be deadly - lawn and garden pesticides often poison these charming mimics. For myself, I'd much rather have a less-than-perfect yard than a world devoid of moonlit mockingbird serenades.