No abstract

Black duck (Anas rubripes) numbers have declined over the past several decades in conjunction with a gradual eastward range expansion of the mallard (Anas platyrhynchos). Introgressive hybridization has been proposed as a principal cause of this decline. We studied a sympatric population of black ducks and mallards to determine the relative contribution of forced copulation and mixed pairs to hybrid production and test the common belief that mallards are more aggressive than black ducks. Mixed pairs (14% of all pairs), not interspecific forced copulation, likely accounted for the 2% hybridization rate on the study area. Sexual and hostile aggression was greater among mallards than black ducks prior to the establishment of territories, but thereafter was similar between the two species.

No abstract

Fidelity of white-tailed deer (Odocoileusvirginianus) to wintering areas was examined in west-central New Brunswick. Wintering areas were located and mapped during aerial surveys in 1975 and 1987–1989. Of 99 wintering areas identified in 1975, 42 were unoccupied 13 years later. Small wintering areas (<50 ha) were more likely to be unoccupied in the subsequent survey than larger ones (>100 ha). Forest cutting had a profound effect on transience of wintering areas. Small clearcuts within a wintering area increased the likelihood of deer use. Wintering areas that were completely clear-cut were likely to be abandoned.

Ovarian and paraovarian cysts were found in 14 of 49 moose (Alees alces) ≥ 1 year old examined in New Brunswick. The pathogenesis of cystic structures in moose in New Brunswick is not known. Breeding success (conception) does not appear to be influenced by ovarian or paraovarian cysts.