Migrating Parasitic Jaegers, on the other hand, offer an excellent system in which to investigate the formation mechanisms and ecological determinants of foraging group size.
In early fall, the sandbar serves as a migratory stopover for Parasitic Jaegers, Common Terns, Black-legged Kittiwakes (Rissa tridactyla), and many shorebird species.
At the start of each block, I counted the abundance (number) of Parasitic Jaegers and of Common Terns (flying and not flying) within one observation perimeter (second-order-patch).
I completed 2015 observation blocks, of which 1247 included Parasitic Jaegers.
Outcome of kleptoparasitic interactions involving Parasitic Jaegers against Common Terns as a function of jaeger group size, at the Portneuf sandbar.
Results obtained in this study are comparable to those that I obtained when investigating the feeding behavior of migrating Parasitic Jaegers at the same site in 1991 and 1992 (Belisle and Giroux 1995), and are also consistent with general patterns found in studies of other mono- and interspecific seabird systems that make use of kleptoparasitism (Furness 1987a, b).
This rapid increase in chasing success rate at small group sizes and the leveling at larger ones are both common trends in kleptoparasitic interactions involving Parasitic Jaegers and terns (Sterna hirundo, S.