Lest you Seantters think you’re alone in your interest in seabird carcasses, here is some comfort and solidarity for you. The Monterey Bay group BeachCOMBERS surveys California beaches reporting on dead birds and marine mammals. Their techniques are very similar to SEANET’s, and many of the same questions have puzzled them in terms of how to interpret the data they collect. In particular, how do we know if seabird mortality observed by beach walkers reflects normal mortality in a population, or is an indicator of a major mortality event? The Common Eider die-offs on Cape Cod certainly beg this question, but without accurate data on live birds at sea, it’s impossible to determine the significance of a few dozen or even a few hundred dead birds on the beach.
In Monterey Bay, Kelly M. Newton, Donald A. Croll, Hannahrose M. Nevins, Scott R. Benson, James T. Harvey, Bernie R. Tershy looked into that precise problem and have published a paper entitled “At-sea mortality of seabirds based on beachcast and offshore surveys” in Marine Ecology Progress Series. In their study, they examined the mortality data collected by beached bird survey volunteers in comparison with at-sea counts of various seabird species. In their model, they also took into consideration weather patterns, prey availability, migration and breeding status and various other factors that might impact mortality. Their findings vary across species of seabird, but indicate some intriguing links between ocean upwelling, prey availability and carcass deposition on the beach.
SEANET finds this study fascinating and inspiring and we hope to ultimately do a similar study to elucidate some of the mysterious die-offs our diligent volunteers detect. Check out the paper and see what you think Seanetters. We think it’s time we started to catch up with the achievements of our west coast counterparts!