Mate Guarding and Extra-Pair Paternity in Northern Cardinals

Abstract

We studied patterns of mate guarding and paternity in 21 pairs of Northern Cardinals (Cardinalis cardinalis) nesting in central Kentucky. DNA fingerprinting revealed that five of 37 nestlings (13.5%) resulted from extra-pair fertilizations (EPFs). Of 19 broods sampled, three (16%) had at least one extra-pair young. Although our observations of male cardinals making extra-territorial movements suggest that some males in the population may actively pursue EPFs, the percentage of extra-pair young in our study was lower than reported for many other passerines. Three non-exclusive factors may have contributed to this low percentage. 1. Male cardinals may gain more from parental efforts than from pursuing extra-pair copulations (EPCs). 2. Females in resident species such as Northern Cardinals probably have more opportunities to assess the quality of prospective mates prior to pairing than do females in migratory species and so EPCs may be less likely to be beneficial to females. 3. Most male cardinals exhibited mate guarding behavior. Males maintained contact with fertile mates 72.8% of the time during initial nesting attempts and, in addition, males followed females more often than females followed males in nine of 10 pairs.