The Sand Paper
This article was originally published in a 2003 issue of The Sand Paper, the member newsletter of the Anza-Borrego Desert Natural History Association.
Hawkwatch Comes to Borrego Springs
by Hal Cohen
Thirty-six turkey vultures put down in the eucalyptus trees directly across from my home on February 28, 2003, at 5:30 p.m. Little did I know that this day would be the beginning of hawkwatching in Borrego Springs, a desert community surrounded by mountains in Southern California, just 80 miles north of Mexico.
The rustling of wings flapping and branches bending was soothing. The vultures settled in for the night. I thought of my move to Borrego a year ago, leaving the Midwest where I counted hawks seriously for many years. I said goodbye to Concordia University on Lake Michigan near Milwaukee, a merlin mainline. No longer would I watch clouds of broadwings at Erie Metro near Detroit or Bald Eagles on the Mississippi. Whitefish Point, Illinois Beach, and Indiana Dunes would be memories. I said goodbye to Mount Hoy just 30 miles west of Chicago, a place without leading lines to funnel hawks. Mt Hoy was my first hawkwatch. It’s here that I honed my skills in hawkwatching. How I yearned for the hours of watching, digging in and looking at puffy clouds, hoping for a few hawks to stream by.
The next morning I followed the birds as they lifted, circled and streamed north then west to avoid the imposing height of Toro Peak at 8700 feet. Coyote Canyon provided an exit from Borrego Valley. The canyon cuts between the San Ysidro Mountains to the west and the Santa Rosa Range dominated by Toro Peak to the north. This access route allows the birds to continue their journey north.
During the first two weeks in March I concentrated my efforts on locating a site to watch the migration of vultures. At this point I was satisfied working with turkey vultures. On March 9th I counted an unknown raptor from a great distance. It looked buteo-like but was slimmer than a redtail. The bird did not register quite right. Later I realized that this was perhaps my first of many Swainson’s hawks to move through the valley.
I located the watch at the junction of Henderson Canyon and Borrego Springs Road.
I returned to the watch site March 2, temperature 83 degrees, 10% clouds, wind ESE 5 mph, humidity 21% visibility unlimited. At 8:11AM 25 Swainson’s kettled up and flew directly overhead and across the ridge. At 8:14 a.m., 8 Swainson’s followed the same route. Birds continued to stream overhead until 8:50 a.m. the totals in less than an hour were 63 Swainson’s and 2 turkey vultures.
On March 11, I left the watch at 9 a..m. and headed home. As I turned south on DiGiorgio Road I spied a kettle (a large group of hawks swirling around presenting the shape of a kettle) of what appeared to be ravens. I stopped my truck and swung my binocs up to reveal a kettle of 16 Swainson’s hawks. They began to stream north and then west through Coyote Canyon.
On April 6 we counted only 210 Swainson’s. The remainder had made it through. Coyote Canyon the prior evening. We were now convinced that the birds were coming into the valley in the evening, roosting and feeding on the caterpillars in the morning. The large group that came in April 5th split with the majority gliding into Coyote Canyon to feed further north.
On April 7 over 100 hawks were on the ground this morning, suggesting that again we missed a movement the prior evening. We were now determined to witness migration into the valley.
A total of 185 Swainson’s departed today. We returned in the evening and spotted 21 hawks descending into the area. Another 30 were already on the ground or in the trees. Migration continued daily with totals for the period April 8-19 of 267. The grand total for the season included 2031 Swainson’s Hawks, 310 Turkey Vultures, 1 Osprey, 2 Northern Harriers, 1 Redtail, 1 Ferruginous Hawk, and 1 Golden Eagle. We spent 74 hours at the watch. Our average hourly total was 31.7 hawks.
Swainson’s Hawks are endangered in California. They migrate from the pampas of Argentina to as far north as Alaska. The central valley of California still has a few nesting birds. The work we have begun on Swainson’s Hawks may help determine if a viable population is increasing. Next spring we will try to retrieve feathers to be used in genetic studies, linking our sightings with nesting Swainson’s further north.
2004 hopefully will bring the hawks back to the valley. Many questions still remain unanswered. We now know, however, that Southern California has a new hawkwatch.
Photos by Ray Spence
About the Author
Join biologist Hal Cohen each spring in Borrego Springs as the annual Swainson’s Hawk Watch gets underway.