Time-activity budgets, body condition, and lipid prediction models of wintering diving ducks on East Texas reservoirs.

摘要

To date, no work has focused specifically upon behavior and body condition of diving ducks wintering on east Texas reservoirs. During November--March, 2003--2004 and 2004--2005 seasons, I (1) developed time-activity budgets, (2) estimated body condition, and (3) developed lipid prediction models for canvasback (Aythya valisineria), lesser scaup (Aythya affinis), and ring-necked duck (Aythya collaris ) during winter on Toledo Bend, Sam Rayburn, and B.A. Steinhagen Reservoirs.; Behaviors were measured for each species using focal individual sampling during both study years. More than 1220 focal samples were collected for canvasback (n = 640), lesser scaup (n = 313), and ring-necked duck (n = 271) during approximately 50 hours of observation during this study. Behaviors varied among species (P 0.001) in the proportion of time spent feeding and locomoting. Ring necked duck spent almost 30% of the time feeding, whereas canvasback spent only 19% of the time feeding, and nearly 40% of the time in locomotion activities. Lesser scaup tended to spend intermediate amounts of time in both behaviors. Time spent in loafing, comfort, and sleeping behaviors were similar among species (P > 0.140); combined these behaviors accounted for 31--34% of time activity budgets for all species combined. Few courtship or agonistic behaviors were observed for any species in either year.; A total of 248 ducks were collected between 8 November 2003--23 January 2004 and 3 November 2004--2 March 2005 to estimate body condition and develop lipid prediction models from morphological and internal tissue measures obtained from the birds. In general, average lipid content of diving ducks during this study ranged between 19--35%, depending on species and age and sex within species. Several significant models (P 0.05) were successfully developed using a combination of morphological and internal fat and tissue measures. Model variables differed depending on species and age and sex within species, although skin mass was an important variable in most models, and alone accounted for 69--86% of the variation in percent lipid content.; This study generated important information of how diving ducks utilize reservoirs in east Texas. Diving ducks in this study had time-activity budgets similar to other studies, and also maintained relatively high lipid levels. This information may suggest that these reservoirs are providing sufficient habitat for wintering diving ducks. However, little is known of the quality/quantity habitat these reservoirs are providing for wintering diving ducks. Therefore, future research is needed to better understand the type of habitat these reservoirs are providing.