VISITS TO WHITE PELICAN NEST COLONIES AT NIGHT REDUCE RESEARCHER IMPACTS ON NESTING SUCCESS

Abstract

Reproductive success of American White Pelicans (Pelecanus erythrorhynchos) was monitored at a nesting colony on Anaho Island, Pyramid Lake, Nevada in 1996 as part of an environmental contaminants study. Reproductive success was normal based on hatching rates of eggs (≥ 75% in undisturbed areas) and survival of nestlings. We entered 2 subcolonies after dark to reduce impacts of our egg collecting activities. Human disturbance from egg collection activities did not result in reduced production at one subcolony, where 80% of eggs in both sampled and unsampled nests resulted in 2-wk-old young. However, in a second subcolony only 60% of eggs in sampled nests and 30% in unsampled nests resulted in 2-wk-old young. Data from this study suggests colony visits for sample collection be done at night rather than the day to preclude gull predation and reduce heat stress on eggs and nestlings.