Placentia Bay is located in southeast Newfoundland between the Avalon and Burin peninsulas. The IBA includes the eastern half of Placentia Bay from Argentia to Cape St. Marys and out to 25 km from shore. There are several low, non-vegetated isolated rocky islets in Placentia Bay. The Virgin Rocks, located 3 km west of Great Barasway are included in the site.
The bay is usually ice-free year round and prevailing southwest winds in summer produce frequent fog banks. Caplin spawn in the shallow waters of Placentia Bay; spawning season is anytime in June and July. The spawning caplin in this area attract large numbers of seabirds and Humpback Whales close to shore.
The large numbers of shearwaters, particularly Greater Shearwater using Placentia Bay is legendary among fisherman and birdwatchers but has been poorly recorded by science. The shearwaters are lured into Placentia Bay to feed on spawning caplin. Greater Shearwater is the most abundant of the three shearwater species occurring there regularly. More than 100,000 individuals have been recorded, which is a globally significant concentration. Sooty Shearwater is the second most common shearwater, whereas Manx Shearwater is typically uncommon (50-100 individuals).
Local breeding seabirds, including Northern Gannett, Black-legged Kittiwakes and Common Murres from Cape St. Marys feed on caplin in Placentia Bay. Thousands of sub-adult Black-legged Kittiwakes feed in the bay, and these individuals are likely from numerous breeding colonies in the North Atlantic. Large numbers of Jaegers may also join the feeding flocks of kittiwakes to steal caplin from the juveniles. Up to 100 jaegers have been seen. Pomarine and Parasitic are most common whereas Long-tailed Jaegers are rare in this area.
Wintering Common Eiders often congregate around the Virgin Rocks. These eiders come into the Placentia Bay coast at various points along a 10 km stretch of coast from Great Barasway to Gooseberry Cove. Approximately 1,000 to 2,000 eiders winter around these rocks.
BirdLife International (2021) Important Bird Areas factsheet: Placentia Bay. Downloaded from http://www.birdlife.org on 25/02/2021.