Mallard duckling care and survival at a wildlife rehabilitation center

Birds are by far the largest group of wildlife cared for by wildlife rehabilitators in British Columbia, Canada. Of this group, mallards (Anas platyrhynchos) are the fifth most common species brought into care. 41% of these mallards are uninjured orphans and require only supportive care until they begin to develop their flight feathers. Although these birds are precocial, and although heat and ad lib food and water are provided, deaths are common in the period between admission and release. An analysis of 937 individual ducklings representing 6 years of data from the Wildlife Rescue Association of British Columbia showed that these deaths are concentrated in the first week after birds are admitted. Logistic regression analyses showed that ducklings that were lighter, admitted with fewer siblings, and that spent longer with the individual who found them were more likely to die in the rehabilitator's care than other individuals. In an experiment, a single, older bird was added to novice broods to act as a "mentor" during the first week of care. Nine novice broods were split at admission and reared in two groups: one housed with a mentor and the other acting as a control. Body size metrics were collected at admission and again at the end of the first week in care, and ducklings in both groups were weighed twice daily during this time. There was no significant difference in mean growth or body condition between treatment and control groups and no experimental ducklings died during the first week. Treatment groups did, however, have less spread in final body weights, mainly because the final weight of the least-thriving individual in each treatment group was significantly greater than in corresponding control groups. The fact that no deaths occurred among the experimental broods in the first week indicates that the experimental housing was better for novice broods than standard facility housing. However, as low growth rates are associated with greater risk of death, the provision of mentors to new broods may reduce the number of birds dying in care where housing is less favorable.Land and Food Systems, Faculty ofGraduat