Mallard Brood Movements in the Canadian Prairie Parklands

We radiotracked 308 mallard (Anas platyrhynchos) broods from hatching until 30 days of age Oij 15 study areas located throughout the Canadian Prairie Parklands to examine patterns of variation in movement frequency and distance. Broods moved an average of 350 m from nests to first wetlands (SO = 390), with 94% of broods moving less than I km. After leaving the nest, broods had a 23% probability of moving to a new wetland each day, but movement probability was a complex function of study area, hatch date, and ducking age, with younger and earlier-hatched broods exhibiting greater movement rates than older and later-hatched broods. Later-hatched broods moved farther than earlierhatched broods and movement distance also varied among study areas. Local wetland characteristics explained some of the among-site variation in movement rates and distances, with movement probability being most strongly correlated with average size of semipermanent wetlands and movement distance being most strongly correlated with total acreage of seasonal wetlands. After 30 days, broods were located an average of 760 m (SO = 610) from their nests, with 95% of all surviving broods located less than 2 km from their nests. Our data illustrated the need for suitable brood-rearing wetlands within a reasonable distance (e.g., \u3c 0.5 km) of waterfowl nesting cover

Assessing breeding duck population trends relative to anthropogenic disturbances across the boreal plains of Canada, 1960-2007

Impacts of anthropogenic disturbance on duck populations in the boreal forest is largely unknown but hypothesized to negatively influence abundance through top-down and bottom-up processes. We examined relationships between population trajectory of duck pairs and anthropogenic disturbances in the Boreal Plains ecozone of western Canada by first controlling for habitat and then assessing whether population trends were related to density of seismic lines, pipelines, roads, and well sites, and distance to agriculture to help focus conservation efforts on the most limiting changes. We also evaluated whether these relationships differed in agriculture encroached vs. unencroached landscapes; distance to agriculture was assessed in unencroached landscapes. Pair counts (1960-2007) obtained from the Waterfowl Breeding Population and Habitat Survey were pooled into nesting guilds (cavity, ground, and overwater). All anthropogenic disturbance features were time invariant. Annual moisture data was used to control for effects of annual variation in breeding season weather. Variation in relative magnitude and direction of effect size indices among anthropogenic disturbances depended on both landscape and nesting guild. Overall, majority of negative relationships occurred with seismic lines and pipelines, while distance to agriculture was positive. Population trends for ground nesters, which suggest overall declines, tended be most negative in regions with high seismic line and well pad density in encroached landscapes and with high seismic line and pipeline density in unencroached landscapes. Cavity nester population trends were generally positive throughout the study area but were lowest in unencroached landscapes farthest from agriculture. Overwater nester trends were generally lowest in encroached landscapes with high densities of seismic lines, roads, and well pads and in unencroached landscapes with high densities of seismic lines, pipelines, and roads. Although our work suggests that anthropogenic disturbances, particularly seismic and pipelines, may merit further consideration as foci for conservation, additional research is needed to quantify demographic implications

True metabolizable energy of American black duck foods

Understanding the true metabolizable energy (TME) of foods is critical to estimating the energetic carrying capacity of landscapes for migrating and wintering waterfowl. We estimated gross energy, nutrient composition, and TMEN (TME corrected for zero nitrogen balance) for 7 foods that are commonly found in the diet of American black duck (Anas rubripes) and other waterfowl wintering along the Atlantic Coast. TMEN values (x-±SE) were 3.66±0.12kcal/g for mummichog (Fundulus heteroclitus), 2.02±0.12kcal/g for grass shrimp (Palaemonetes intermedius, P. pugio, and P. vulgaris), 1.57±0.11kcal/g for fiddler crabs (Uca minax, U. pugilator, and U. pugnax), 1.42±0.13kcal/g for sea lettuce (Ulva lactuca), 1.39±0.12kcal/g for saltmarsh cordgrass seeds (Spartina alterniflora), 1.10±0.14kcal/g for widgeon grass vegetation (Ruppia maritima), and 0.77±0.16kcal/g for saltmarsh snails (Melampus bidentatus). TMEN estimated for foods in this study will assist conservation planners in carrying out bioenergetics modeling along the Atlantic Coast