Extreme Water Level Fluctuations Limit Breeding of Western and Clark's Grebes at San Carlos Lake, Arizona
The first known nesting of Western and Clark’s Grebes (Aechmophorus occidentalis and A. clarkii) at San Carlos Lake in central Arizona was confirmed in 2005 and reported in 2 subsequent years. From many personal observations, analyzing eBird data, and reviewing water level records, I have determined that the acute fluctuations in water level restrict available habitat for nesting most years at the lake. Sharp drops in water level also may reduce the number of grebes. I also detected differences in the feeding behavior of the two grebe species at this location.