San Francisco Bay NWR Complex
Pacific Southwest Region

The Murre Maniac
The Common Murre Project Update April 2008

A New Season!

The month of April has kicked-off another breeding season for the seabirds that colonize Devil’s Slide Rock and the Devil’s Slide Mainland. The beginning of the month was chaotic for the Common Murres as they defended territory and shuffled around the rock. Now that the end of the month has arrived, most of the Murres have paired up with a mate and stayed on their territories most of the day. Within the three monitored plots on Devil’s Slide Rock, we have spotted approximately 192 breeding pairs. The first egg of the season was seen on April 29 th on Devil’s Slide Rock, but we are yet to see one on the mainland. As far as the numbers of Murres are concerned, a high count of 785 birds was seen on Devil’s Slide Rock, while 215 birds were counted on the Devil’s Slide Mainland.

Common Murres on Devil's Slide Mainland
Common Murres on Devil’s Slide Mainland

The Brandt’s Cormorants have also been busy setting up territories, attracting mates, and gathering nesting materials. Although the Cormorants were off to a slow start earlier in the month, they have picked up the pace and there are at least 68 territories on the mainland, and 28 on Devil’s Slide Rock. We have yet to see any Brandt’s eggs, but we are patiently waiting and monitoring!

The Devil’s slide mainland is hosting a variety of other bird’s nests. There are eight Pelagic Cormorant nests, one of which has 2-3 eggs. There is also a pair of Peregrine Falcons, Great Horned Owls, and Common Ravens nesting nearby. We are excited to see how all these species will interact as the breeding season of the Common Murre begins!

April 2008 Colony Counts of Devil’s Slide Rock
# Murres
April 22
April 24
April 26
April 29

*Compiled by Erica Donnelly

Last updated: September 1, 2011