The eagle-eyed bird watcher may soon notice there is another large bird mingling with the turkey vultures and soaring on the wind currents above Borrego Springs.

Any day now, the annual migration of Swainson's hawks will begin as the birds lay over here during their northern migration.

In fact, it was a keen observer in 2003 who noticed there was something different about the vultures roosting in the trees at the Roadrunner Club. They were not vultures.

Retired biologist and avid birder Hal Cohen recognized that Borrego Springs was on the migration path of the magnificent Swainson's hawks.

As an experienced hawk watcher, Cohen launched Borrego Hawkwatch which will celebrate its 20th year this spring.

Migration times can vary somewhat, but the peak is generally between mid-March and early April.

Cohen and a dedicated group of volunteers will be in the field daily to record the number of birds that visit Borrego Valley on their long journey from South America as far north as the Arctic slopes of Alaska.

The morning Hawkwatch site is located on DiGiorgio Road, 2.8 miles north of Palm Canyon Drive. Evening observations are conducted on Borrego Valley Road, 1.8 miles north of Palm Canyon Drive. Visitors are welcome.

Migration numbers can also fluctuate depending on available food. The highest number of migrating hawks recorded have been nearly 8,000 in years of abundant rainfall.

Along with the rain comes plants, followed quickly by the huge caterpillars of the white-lined sphinx moth. Those tasty caterpillars provide a huge source of energy needed by the migrating birds.

Rainfall this year has already produced a bumper crop of plant growth, and there are high hopes that caterpillars will soon follow. That could mean big numbers of migrating hawks this year.

When the migration reaches its peak, birders are in the field each morning to watch them lift off from overnight roosts.

To conserve energy, these large hawks will wait for air currents to begin rising and then they will push off from their roosts and begin circling as they gain altitude.

Sometimes hundreds of the hawk will join into a formation called a kettle that resembles a tornado of birds circling and rising until they catch a northerly air current.

For more information on Hawkwatch, visit http://www.abdnha.org/Hawkwatch.html.

Contact Ernie @ Packtrain.com or follow http://erniesoutdoors.blogspot.com/