Length of day, singing birds herald the arrival of spring
On Wednesday I made a quick trip down to Phoenix, allowing enough time to do a little birding in the Sonoran Desert along the way. I love the Sonoran Desert. I grew up in Tucson and have a great fondness for the flora and fauna of the desert.
I took the Black Canyon City exit number 244 off of Interstate 17, also known as Coldwater Canyon Road. As you come off the exit ramp, on your right is a street named Maggie Mine Road that doubles back parallel to I-17. The road passes through some amazing upland Sonoran Desert habitat, rich with saguaros, prickly pear, cholla, palo verde and mesquite.
As I rounded a bend in the road, I was greeted by a beautiful male cardinal sitting at the top of a shrub, about eye level - species 100 for me on my 2009 County List. I couldn't have scripted this! What a stunning find for my one-hundredth bird species in Yavapai County this year.
Continuing north on Maggie Mine Road, I added more species to my 2009 list - phainopepla, cactus wren, curved-billed thrasher, black-throated sparrow, gilded flicker, Costa's hummingbird, verdin, and Inca dove.
One of the keys to successfully reaching the goal of 209 species in 2009 is to visit as many different habitats as you can. I knew spending a little time in the desert would add several species to my list, as I had not yet birded this year in the Sonoran Desert.
Here in Prescott we are starting to see signs of spring but in Black Canyon City at 2,000 feet in elevation spring is already well under way. Wildflowers are blooming, and the desert floor is a carpet of small green plants. The birds were singing up a storm - especially cardinals and black-throated sparrows.
You have probably noticed in your neighborhood that the birds are beginning to sing more and more. You will also notice that as it gets lighter earlier, the birds sing earlier. Why do birds sing more in springtime? What triggers this change in behavior?
For wild birds, length of day is the cue that triggers the production of testosterone in males. Bird skulls are very thin, allowing light to penetrate the bird's skull and reach critical brain cells that respond to increased light, which in turn increases the production of testosterone.
As testosterone levels increase, the vocal control area of the brain begins to increase in size, resulting in increased singing during breeding season.
Birds create a variety of vocal sounds, but on a very basic level birds produce what are referred to as "call notes" and "songs," some of which can be very complex. Generally speaking (with a few exceptions) only male birds sing, while both males and females can produce call notes.
An interesting fact about birds is that they have two sets of vocal chords - one set is controlled by the right side of the brain, and the other set is controlled by the left side of the brain - making it possible for birds to sing two different songs simultaneously!
Later in summer, as the days begin to shorten, the reverse process occurs. Less light reaches critical brain cells that respond to light, so the production of testosterone gradually slows down, and singing by males decreases. Nature sure is amazing!
There is nothing like the singing of wild birds to herald the approach of spring. Happy birding!
If you have specific questions or issues related to wild birds which you would like discussed in future articles, you can submit them to Jay's Bird Barn, 1046 Willow Creek Road, Suite 105, Prescott, AZ 86301 or log onto www.JaysBirdBarn.com and click on "Ask Eric," which will link you with my e-mail address Eric@JaysBirdBarn.com.
Eric M. Moore is the owner of Jay's Bird Barn and has been an avid birder for more than 40 years.
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