Mahone Bay Roseate Tern Recovery Project

2009/2010

BCAF conducted bay-wide surveys a maximum of three times per week from May 20th to August 18th, 2009. These surveys were completed from the mainland and from a 20’ Boston Whaler using binoculars and/or a spotting scope. The surveys were implemented to first identify the location of tern colonies in Mahone Bay (tern distribution) and then to monitor tern abundance, productivity, and reproductive success. BCAF also monitored gull colonies and threats to terns (anthropogenic disturbances and predation). These surveys recorded bird observations, predation events, weather, and any other information deemed useful when determining tern stewardship options.

Ten islands were visited in 2009 to determine tern distribution in Mahone Bay. Based on observations from boat and land, terns attempted to nest on Crow, Gully, and Westhaver Islands; being successful on Westhaver Island only. “Seabird Nesting Area – Do Not Disturb” signs were placed on the above three islands (2 signs per island), warning boaters to stay away from the islands as they were important seabird nesting areas. Tern presence was also observed on Meisner’s, Quaker, Mash, Mason, Spectacle, Saddle, and Pearl Islands. Only Common terns were confirmed in the bay; therefore, no Roseate terns were nesting on Gully and Westhaver Islands.

In 2008 and 2009, Westhaver and Gully Islands hosted the two largest tern colonies in Mahone Bay. In 2009, the observed abundance on Westhaver and Gully Islands was 105 and 80 terns, respectively. Tern nest and egg counts were conducted on Gully and Westhaver Islands mid June. Gully Island had 119 nests, whereas Westhaver Island had 163 nests. Compared to 2008, the number of nests on Westhaver Island increased by approximately 60. Nest and egg counts on Gully Island were not available from 2008. To monitor reproductive success of tern colonies, BCAF conducted fledgling counts late July. On Westhaver Island, a maximum of 50 juvenile terns were observed along the coastline. Therefore, the tern colony on Westhaver Island had reproductive success in 2009. A fledgling count was attempted on Gully Island; however, only 22 adult terns were present. Unfortunately, Gully Island did not successfully fledge tern chicks this field season.