American Black Duck and Mallard Breeding Distribution and Habitat Relationships along a Forest–Agriculture Gradient in Southern Québec

Abstract

Although the American black duck (Anas rubripes) has been designated a priority species in eastern North America, no systematic survey has been done in the agricultural lowlands of southern Québec, where the species is suspected to be relatively abundant and cohabits with the mallard (Anas platyrhynchos), often considered as a competing species. During the spring of 1998 and 1999, we surveyed breeding waterfowl in 343 4‐km2 plots distributed in the lowlands of the St. Lawrence Valley and Lac‐Saint‐Jean, Canada, and in agricultural areas of Abitibi‐Témiscamingue, Canada. American black duck densities were higher in dairy farm and forested landscapes (>39 indicated breeding pairs [IBPs]/100 km2) than in cropland landscapes (8 IBPs/100 km2). Mallard densities were similar across all landscape types (30–43 IBPs/100 km2). Habitat modeling using data derived from satellite imagery indicated that the presence of black ducks decreased with increasing areas of corn, ploughed fields, and deciduous forests, whereas it was favored in areas where topography was undulating with slopes of 10–15%. The same parameters had the opposite effect on mallard presence. The odds of black ducks being present were doubled where mallards were present, indicating that both species seem to be attracted to areas supporting adequate habitats, which contradicts the hypothesis of competition between these 2 species to explain for recent declines in the black duck population. Results of our habitat analyses support the hypothesis that habitat changes may be a primary factor leading to these declines. Dairy farm landscapes are of great importance for black ducks, and the conversion of this type of landscape toward a cropland landscape represents a threat to an important portion of the population of this species.

Identifying hybrids & the genomics of hybridization: Mallards & American black ducks of Eastern North America

“…However, reduced representation of non‐western assignment and OW A haplotypes in black ducks (i.e., tendency of F1 black duck x feral hybrids to backcross into black ducks) may be due to black ducks showing assortative mating, in general, or simply tend to not overlap the primary habitat used by feral mallards (Osborne et al, ). Specifically, feral mallard success to adapt to human‐disturbed habitat (Diefenbach & Owen, ; Maisonneuve et al, ; Rogers & Patterson, ) and the black duck's natural reclusiveness and evasion of human‐disturbed habitats (Hepp et al, ) may simply limit the chance of contact between black ducks and feral mallards. Additionally, we hypothesize that mallard‐black duck hybrids may be using human‐dominated landscapes more often than their wild parentals, and thus are primarily coming into contact with other feral mallards (e.g., Hubb's Principle; Hubbs, ).…”

Spatial and temporal variation in harvest probabilities for American black duck

“…; Maisonneuve et al. ; Brook et al. ), harvesting is the only source of mortality that managers can actively control.…”

Occupancy Patterns of Breeding American Black Ducks

“…Similar to previous work, we did not find that mallards excluded black ducks from breeding wetlands. In southern Québec, black ducks were twice as likely to be present when a mallard pair also occupied a wetland (Maisonneuve et al ). McAuley et al () found no evidence of competitive exclusion by mallards and found black ducks most often occurred on breeding wetlands with another pair of duck species.…”