Summary
Studies of the mating strategies of birds are increasingly shifting their focus to the role that females take in controlling copulation (Hunter et al. 1993, Petrie 1992, Birkhead and Moller 1993). In some avian species, females appear able to control whether copulations occur by accepting or rejecting copulation attempts (BjSrklund et al. 1992, Lifjeld and Robertson 1992, Westneat 1992). Similarly, females of some species actively solicit copulations by seeking the extra-pair male in his own territory (Smith 1988, Kempenaers et al. 1992, Venier et al. 1993). In species where females do control the outcome of copulation attempts, there is a need to, first, determine the extent that extra-pair copulations (EPCs) lead to fertilizations and, second, establish potential benefits that a female may obtain by engaging in EPCs.
Methodology
We conducted parentage analyses on eight families of Black-capped Chickadees that bred in the 1992 season at the Queen's University Biological Station, Lake Opinicon, Ontario, Canada (4403'N, 76020'W). This population has been color banded since 1987. We caught adult birds with Potter traps baited with seed, or by netting adults at the nest cavity with mist netting fashioned into a loop on the end of extendible poles. We collected blood from adults and young by brachial puncture; 75 uL from adults and 50 uL from nestlings at 8-12 days posthatch, as nestlings will fledge prematurely if disturbed after 12 days(Smith 1991). Blood was stored in either 1 x TNE2 blood preservative or Queen's Lysis buffer (QLB) (Seutin et al. 1991). Samples were stored frozen (TNE2) or at 40C (QLB), until DNA was extracted.