Predicting stranding patterns of live oiled seabirds, carcass deposition, and carcass retention in Monterey Bay

Beach surveys for live and dead beachcast birds are an economical and practical way of determining seabird population health. Using long-term surveys creates a baseline mortality profile by determining the areas and time of year birds are likely to strand as well as what oceanographic factors cause the deposition and retention of seabird carcasses on beaches. I hypothesized that 1) seabird initial carcass deposition in Monterey Bay would be greater in the southern part of the bay than in the northern part due to oceanographic factors, and 2) seabird carcass retention (how long carcasses stayed on the beach) would be greater in the North Bay than the South Bay due to beach profile characteristics. I utilized BeachCOMBERS beach survey data from 2005 to 2012 to determine patterns of seabird carcass deposition and retention in Monterey Bay and obtained wind speed, wind direction, wave height, tide height, and wave height + tide height (swell impact) from buoys. A backwards multiple regression on the averaged yearly deposition (birds km-1) as affected by oceanographic factors in Monterey yielded significant effects only in the year 2011, with wind speed being the main factor. A two-way ANOVA on the percent of carcasses retained from the previous month with month and zone as independent factors yielded significant effects of both, although location (zone) had a more significant effect. Variability in deposition and retention highlighted the need for continued long-term surveys to accurately determine seabird presence and mortality in Monterey Bay.