Proposed Abstract Title

Seabird abundance, distribution and fine-scale variation in San Juan Channel - Fall 2015

Type of Presentation

Poster

Session Title

The Biological and Physical Factors Driving Marine Bird Population Dynamics in the Salish Sea

Location

2016SSEC

Description

Seabirds are an important part of marine ecosystems. They act as apex predators and are indicators for overall ecosystem health. Recent studies have suggested an overall decline in seabird populations in the Salish Sea. For the past ten fall seasons, PEF apprentices have monitored seabird abundance and community composition in the San Juan Channel to assess overall population status. Consistent with other years, strip transects were performed weekly in a 21.5 km corridor along the channel. This season, no exceptional change in abundance or community composition was found. Most within season variation can be attributed to migratory patterns, but some key residential species have dramatic fluctuations that may be attributed to tidal influence. PEF apprentices have continued to investigate the relationship between tidal phase and seabird abundance in the southern San Juan Channel using a smaller (3.9 km) transect corridor on an hourly scale. When isolating peak current speed at flood tide, decreases in seabird abundance as current speed increased were found, a contrast to previous studies. A surge in abundance occurs 50 minutes after fast flood suggesting ideal feeding conditions are not directly correlated with current speed and could be delayed due to bathymetric features. Further studies could be done to isolate the next part of the tidal cycle.

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Seabird abundance, distribution and fine-scale variation in San Juan Channel - Fall 2015

2016SSEC

Seabirds are an important part of marine ecosystems. They act as apex predators and are indicators for overall ecosystem health. Recent studies have suggested an overall decline in seabird populations in the Salish Sea. For the past ten fall seasons, PEF apprentices have monitored seabird abundance and community composition in the San Juan Channel to assess overall population status. Consistent with other years, strip transects were performed weekly in a 21.5 km corridor along the channel. This season, no exceptional change in abundance or community composition was found. Most within season variation can be attributed to migratory patterns, but some key residential species have dramatic fluctuations that may be attributed to tidal influence. PEF apprentices have continued to investigate the relationship between tidal phase and seabird abundance in the southern San Juan Channel using a smaller (3.9 km) transect corridor on an hourly scale. When isolating peak current speed at flood tide, decreases in seabird abundance as current speed increased were found, a contrast to previous studies. A surge in abundance occurs 50 minutes after fast flood suggesting ideal feeding conditions are not directly correlated with current speed and could be delayed due to bathymetric features. Further studies could be done to isolate the next part of the tidal cycle.