Pigeon Guillemots (Cepphus columba) are an important indicator species for the Puget Sound because they are one of the few seabirds that breed here and many remain through the winter. In spring, approximately 1000 birds gathered at 24 breeding colonies around Whidbey Island where they nest in bluff burrows. Whidbey Audubon Society volunteers have monitored those colonies since 2004. Beginning in 2007, paid interns were charged with identifying the prey delivered to the chicks.
Pigeon Guillemots feed themselves and their young almost entirely on benthic fish, which they find in the vicinity of Whidbey Island. The success of this population depends on a healthy marine environment and an ample supply of fish.
During the breeding season (late June through late August), volunteers visited each colony weekly and observed the birds for one hour/visit. They counted the birds, mapped the active burrows and identified prey delivered to the nest burrows. A burrow was deemed active if adults entered the burrow or if they delivered food to the burrow. In 2008, 225 active burrows were identified, in 2009, 255 were identified and in 2010, 227 were identified. About 45% of the birds attempted to breed.
Prey deliveries began in late June and reached a peak in late July. Prey were identified visually using binoculars and spotting scopes. Prey was delivered to 70% of the active burrows indicating at least one chick had hatched. In 2008 we observed 754 fish deliveries to 161 burrows, in 2009 we observed 1288 deliveries to 183 burrows and in 2010 we observed 1237 deliveries to 227 burrows. The fish delivered to the burrows were primarily gunnels (56%) or sculpins (25%). The other 19% of the deliveries were either unidentified or were prey other than gunnels or sculpins. The success of the Pigeon Guillemot population appears to be dependent upon the population of these bottom fish.
We also study these birds to help educate island residents and others about the importance and joy of having guillemots in our waters. Our dedicated group of citizen science volunteers spread the word with their friends and neighbors as well as beach walkers. We monitor the disturbances to the birds and attempt to decrease human-caused disturbances.