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- Title
Reproductive Rates in Lesser Scaup (Aythya affinis) in Southwestern Manitoba: Another Look at the Data.
- Authors
HAMMELL, GORD
- Abstract
Surveys indicate that Lesser Scaup (Aythya affinis) populations declined during the early 1980s and have since remained below conservation goals. Reasons suggested for the decline include chemical contamination, climate change, and reduced food resources. According to the latter theory, reproductive success of Lesser Scaup has declined because females now arrive on the breeding grounds with fewer nutrient reserves than in the past and this diminished body condition is the result of reduced food resources available at wintering and/or migration areas. To determine whether reproductive success has declined over time, I examined selected Lesser Scaup reproductive rates from 2008 to 2014 in southwestern Manitoba and compared them with those recorded before the continental population decline. Estimated productivity (age class 11a broods/pair), hatching date, la and 11a brood size, duckling survival rate (first sighting to age class Ha), and proportion of age class Ila broods with females in attendance were unchanged from values recorded in 1970-1972. Thus, if females are arriving on southern breeding areas with reduced body reserves, they may be recovering these losses before nesting, enabling them to attain reproductive rates similar to those in the past. In addition, these results are consistent with the hypothesis that reduced food resources at non-breeding areas could affect recruitment of southern prairie-parkland breeders to a lesser extent than northern breeders because of the longer time between arrival and egg-laying in the south.
- Subjects
LESSER scaup; BIRD reproduction; BIRD conservation; EFFECT of climate on animal migration; BIRD behavior; NEST building; REPRODUCTION
- Publication
Canadian Field-Naturalist, 2016, Vol 130, Issue 2, p110
- ISSN
0008-3550
- Publication type
Article
- DOI
10.22621/cfn.v130i2.1834