The population dynamics of Common Terns (Sterna hirundo) at Oneida Lake, NY

Background/Question/Methods

The Common Tern (Sterna hirundo) is a threatened species in New York State. This is largely due to the loss of suitable nesting habitat which is strongly correlated with landfill-subsidized increases in gull populations since gulls also compete for similar nesting space (Mattison, 2006). The Common Tern colony at Oneida Lake and has been reduced to one nesting island on the lake, Little Island, which is reserved annually for the tern colony by Cornell University using mon-filament gull exclusion devices. Cornell University has monitored and managed the colony since 1976, and continues implementing methods such as chick banding, adult recapture, and habitat enhancement, including chick shelters and providing additional nesting substrate. These management practices continued during the 2014 field season.  The NYSDEC management goal for the Oneida Lake population is to reach stability with at least 500 nesting pairs per year. Restoring the Common Tern to its native habitat enhances biological diversity and allows for the persistence of a species with its own intrinsic value. Here, we evaluate the effectiveness of these management actions in 2014 in a historic context.

Results/Conclusions

As in previous years, gull populations were successfully excluded using a monofilament grid on Little Island.  This prevented most gulls from using this island although high gull numbers have precluded terns from colonizing additional islands on the lake. The management goal of 500 nesting pairs at Oneida Lake was not achieved in 2014 due to high water events, and only sporadically achieved in the past due to Little Island’s limited space capacity.  Increasing nesting area on Little Island or adding gull exclusion devices to other islands will be necessary to reach the management goal for this species on Oneida Lake.