Apparent survival of two trans-equatorial migrant seabirds breeding in Canada
LE3 .A278 2015
2015
Mallory, Mark Shutler, Dave
Acadia University
Master of Science
Masters
Biology
Long-lived species, such as seabirds, typically have slow reproductive rates, so that even slight reductions in adult survival could lead to substantial population declines. Adult survival is therefore an important monitoring tool, used to assess health of seabird populations. Using Program MARK, I estimated annual apparent survival of adults of two seabird species breeding in Canada: Leach’s Storm-Petrel (Oceanodroma leucorhoa), on Bon Portage Island, Nova Scotia; and Sabine’s Gull (Xema sabini) on Nasaruvaalik Island, Nunavut. In addition, I examined potential variables influencing adult survival for both species. For Leach’s Storm-Petrels, I found evidence of positive effects of VHF tag attachment; however, this was likely due to sampling bias and/or limited data. I also found preliminary evidence of Herring Gulls (Larus argentatus) having negative effects, but further years of data are needed to improve confidence in this result. Regardless, adult survival of Leach’s Storm-Petrels at this colony was low compared to estimates for similar species (e.g., > 0.90 for many albatrosses and petrels), but similar to recent estimates for other Leach’s Storm-Petrel colonies in Atlantic Canada. For Sabine’s Gulls on Nasaruvaalik Island, survival was high and generally constant (0.90 ± 0.03). However, after combining data for that colony with data for a low Arctic colony, I detected an influence of anomalous climate conditions, with reduced survival in a year with a high, positive value for the Tropical Northern Hemisphere pattern. This is a teleconnection pattern that has anomalies centred over the Gulf of Alaska, Hudson Bay, and Mexico. For both species, additional data are needed from respective study sites to refine current estimates and to help identify and address factors that negatively affect their survival.
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https://scholar.acadiau.ca/islandora/object/theses:356
