Linking decision support systems for ducks with relative abundance of other grassland bird species

Abstract

Decision support systems (DSS) that integrate long-term duck population and land use data are currently being used to develop conservation programs on the Canadian prairies. However, understanding inter-relationships between ducks and other grassland bird species would greatly enhance program planning and delivery among various bird conservation initiatives. Therefore, to achieve these goals, grassland bird species richness and relative abundance were compared between areas of low, moderate and high predicted waterfowl breeding densities (strata) in the southern Missouri Coteau, Saskatchewan. Roadside point counts were conducted during spring 2001 and 2002, and habitats were delineated within 400 m radius of each point.

More birds of more species were encountered in the high density waterfowl stratum when compared with low but species that tended to co-occur with ducks were primarily wetland-associated. Overall, duck and other grassland bird species richness and abundance were moderately correlated (0.69 > r > 0.37, all Ps < 0.05); strong positive correlations between priority species of conservation concern and northern pintails were not found. No difference in mean number of priority grassland species occurred among strata, but differences were found for both number of species and total birds detected among routes within strata. High duck density stratum was more heterogeneous, consisting of greater areas of forage, shrub, wetlands, and open water bodies whereas low stratum contained larger, more uniformly-shaped habitat patches and greater proportion of cropland.

Ordination analyses revealed that most priority species occurred in grassland-dominated sites with lower shrub area and wetland density whereas most wetland-associated species, including ducks and 2 priority species (Wilson’s phalarope and marbled godwit) inhabited cultivated areas with higher wetland density. Ducks and priority species generally did not co-occur at the stop-level in highly heterogeneous landscapes but suitable habitats for both groups may exist in near proximity. In homogeneous landscapes, ducks and other wetland-associated common species were less abundant because of limited number of suitable wetlands. To achieve these dual goals, conservation efforts should be focused in areas containing wetlands adjacent to contiguous tracts of native pasture.