San Juan Channel Seabird Abundance Patterns of Fall

Abstract

Seabirds are an important component of many marine ecosystems, but are in decline in many parts of the world. While some studies have shown that Salish Sea seabirds are declining, PEF has found no evidence of this decline. I attempted to characterize the seabird community of fall 2013, as well as try to establish whether or not tidal influences have been biasing our data collection. I used strip transect survey methods to analyze the seabird community of 2013 and compare it to previous years, and looked at three tidal metrics (tidal current speed, tidal current direction, and maximum tidal exchange) to determine whether or not PEF has a sampling bias in regards to tides. The abundance of seabirds in 2013 was relatively low, but not anomalously so, and the community composition for this year is consistent with that of past years. Furthermore, analyses of the tidal metrics yielded no evidence of sampling bias. Therefore, it is likely that the interannual patterns observed by PEF in the past are real and are possibly due to global climate patterns.