Diary

Kathy Molina,

       Well, it’s happened at last–the thermometer is finally cranking up to triple digits. The Salton Sea has just experienced a most unusual spring and, thankfully, it seems to have come to an end. Some–well, most–people call it a blessing, but I’ve been quite impatient with these mild daytime temperatures and soft, cool breezes. I’m ready to sweat! I’m based at the National Wildlife Refuge here, completing a study of parental behavior in two species of water birds related to gulls– gull-billed terns and black skimmers. These birds nest on small earthen islets, placing their nests directly on the ground and avoiding any vegetation or other objects that would provide shade and moderate the environmental conditions at their nests. And here they sit, one parent or the other, hour after hour and day after day, under a blazing sun. To leave their nests uncovered, even for a few minutes during midday, is to surrender them to the sun. Unprotected eggs and very small chicks hard-boil in minutes.
       Adaptive behaviors, and sometimes differences in physiology, allow birds such as these to nest successfully in seemingly harsh and taxing environments. They pant and flutter and elevate their feathers to provide a barrier to solar radiation. They fly out over the water and, with landing gear lowered, literally “ski” on the water surface, picking up water that wets their breasts and bellies. It is these thermoregulatory behaviors, coupled with the partitioning of parental duties, that I find most intriguing. How do these hot environments influence the sharing of parental responsibilities? Do males and females provide similar amounts of food to offspring or spend similar amounts of time at the nest site under these conditions? Do the sexes defend the nest and territory equally? What prompts parents to soak their belly feathers and transport water back to the nest and eggs, parental thermoregulation or the thermal requirements of the eggs? These are a few of the questions I’m trying to answer as I hunker this afternoon under a thin veil of camouflage, sucking on a lukewarm bottle of Gatorade. With telescope trained on a nesting islet, I watch constantly during my three hour observation period and record the comings and goings of the pair attending Nest No. R48.
       Now that you know why I’m here, let me provide a brief introduction to this unique wetland. This inland sea, one of the largest in North America, spans the extensively farmed Imperial and Coachella valleys. Veritable “horns of plenty,” these areas produce year-round, with thousands of acres devoted to vegetables, alfalfa, and cotton. Cloudless skies, hot temperatures, and an intricate system for moving unimaginable amounts of irrigation water away from the Colorado River make it all possible. Although resting in an ancient lake bed, the Salton Sea is now maintained by agricultural and industrial waste water. Today considered an agricultural sump (with questions of water quality and its effects on wildlife just beginning to be raised), the Salton Sea continues to be an integral part of the lower Colorado River and delta system.
       Although hundreds of thousands of shorebirds grace the sea’s muddy shores during migration, and similar numbers of waterfowl plop in and stay through winter, what dazzles me most are the thousands of nesting terns, skimmers, plovers, herons, egrets, and cormorants that use this sea as a bird nursery.