Seabird census protocol development and evaluation for Schoodic Island

Walczyk, Sandy; Anderson, John

Following from abstract: "Schoodic Island, a significant seabird nesting colony within Acadia National Park, was censused for gulls, cormorants, eider ducks, and leach's storm petrels during the summer of 2007. Our results suggest that: 783 gulls, consisting of approximately 85% herring gulls, and 15% greater black-backed gulls nested on the island in 2007. This represents a distinct shift in species ratio and probable decline in numbers since the last estimate in 1977. 700 common eiders nested on the island, more than double the number reported in 1977. 250 double-crested cormorants nested, a number comparable to 1977. Fewer than 100 black guillemots nested, but this is still greater than the 20 recorded in 1977. Few if any Leach's Storm petrels nest on the island. Assessment of different techniques (aerial overflight, ground nest count, and boat count) revealed inconsistencies both within and between each technique, but all techniques confirmed Schoodic's status as an important nesting island. Boat counts generally showed the highest variability between observers, but were the least intrusive and required the minimal amount of time and resources. Results were heavily affected for cormorants due to unique features of the terrain. Ground nest counts provide the most information and are probably the most repeatable between years, but created maximal disturbance. Aerial counts were comparable with both the other techniques for gulls and cormorants, but were inapplicable to eiders, guillemots, and petrels. We recommend that National Park Service managers establish specific guidelines for desired census precision and accuracy before adopting any particular technique or combination of techniques. We further encourage that some sort of regular census schedule be established (we would encourage a minimum of once every 5 years) in order to determine any trends in species presence." ----------------- Research recommendations: 'We recommend that National Park Service managers establish specific guidelines for desired census precision and accuracy before adopting any particular technique or combination of techniques. We further encourage that some sort of regular census schedule be established (we would encourage a minimum of once every 5 years) in order to determine any trends in species presence.' /STUDY LOCATIONS:/ /ISLANDS/Schoodic Island/

Seabird census protocol development and evaluation for Schoodic Island

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