Seabird Diversity Along a Latitudinal Gradient Within the Drake Passage

Though seabirds constitute only a small portion of all bird species, they are indicators for the health of the marine habitats on which they rely. This is especially true of the seabirds that inhabit the Southern Ocean and Antarctic Peninsula. The study of indicator species such as these makes it feasible to track changes in ecosystems that are either complex or otherwise difficult to study. Without data on these indicator species, vital, but difficult to access ecosystems like those in the Southern Ocean are not easily studied. In order to collect data on current Antarctic seabird numbers and distributions, we sampled along a latitudinal transect from 60 o S to 64 o S, from just south of Cape Horn to the northern part of the Antarctic Peninsula. This was accomplished during travel across the Drake Passage by sighting and keying all seabirds visible from the bridge of the vessel four times each day, for 15 minutes at a time. Additional data were collected during these periods such as wind speed, sea surface temperature, precipitation and latitude. Data were collected on 19 seabird species and though distributions and abundance vary, a comprehensive analysis was achieved using a linear regression to determine the correlation between species diversity, calculated using the Simpson’s Diversity Index, and latitude. Although the result was not statistically significant, most likely due to the low number of observations, these data still provide valuable reference points by which to track future changes in the marine ecosystems of the Southern Ocean.