Population ecology of Lesser Scaup (Aythya affinis) in subarctic taiga

Trauger, David L.

doi:10.31274/rtd-180813-1517

Cited by 24 publications

(14 citation statements)

References 41 publications

(7 reference statements)

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“…Spring breeding-pair surveys assume that all pairs attempt to breed Blohm 1992, Nichols et al 1995); however, we found that L 33% of lesser scaup pairs on our study site were not breeding. Recruitment estimates based on annual breeding-pair surveys may be overestimating productivity of scaup pairs in the boreal forest, which in turn may have implications for harvest management of these birds (Trauger 1971). Managers should reevaluate the definition of a breeding pair and the assumption that all scaup pairs, no matter where they are counted during annual spring surveys, have equal potential productivity.…”

Section: Management Implicationsmentioning

confidence: 99%

Lesser Scaup Breeding Probability and Female Survival on the Yukon Flats, Alaska

et al. 2009

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Information on the ecology of waterfowl breeding in the boreal forest is lacking, despite the boreal region's importance to continental waterfowl populations and to duck species that are currently declining, such as lesser scaup (Aythya affinis). We estimated breeding probability and breeding season survival of female lesser scaup on the Yukon Flats National Wildlife Refuge, Alaska, USA, in 2005 and 2006. We captured and marked 93 lesser scaup with radiotransmitters during prelaying and nesting periods. Although all marked lesser scaup females were paired throughout prelaying and incubation periods, we estimated breeding probability over both years as 0.12 (SE 5 0.05, n 5 67) using telemetry. Proportion of lesser scaup females undergoing rapid follicle growth at capture in 2006 was 0.46 (SE 5 0.11, n 5 37), based on concentration of yolk precursors in blood plasma. By combining methods based on telemetry, yolk precursors, and postovulatory follicles, we estimated maximum breeding probability as 0.68 (SE 5 0.08, n 5 37) in 2006. Notably, breeding probability was positively related to female body mass. Survival of female lesser scaup during the nesting and brood-rearing periods was 0.92 (SE 5 0.05) in 2005 and 0.86 (SE 5 0.08) in 2006. Our results suggest that breeding probability is lower than expected for lesser scaup. In addition, the implicit assumption of continental duck-monitoring programs that all paired females attempt to breed should be reevaluated. Recruitment estimates based on annual breeding-pair surveys may overestimate productivity of scaup pairs in the boreal forest. (JOURNAL OF WILDLIFE MANAGEMENT 73(6):914-923; 2009) N MJ~x J P J i~1Ŝ J

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Section: Management Implicationsmentioning

confidence: 99%

Lesser Scaup Breeding Probability and Female Survival on the Yukon Flats, Alaska

et al. 2009

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“…Most of what we know about the nesting ecology of lesser scaup comes from studies in the southern portion of their breeding range, either in the prairie parklands near the town of Erikson in southwestern Manitoba, Canada (Afton 1983(Afton , 1984Afton and Ankney 1991;Afton and Hier 1991;Koons 2001) or on the St. Denis National Wildlife Area in central Saskatchewan, Canada (Dawson and Clark 1996). Few studies have been conducted in the boreal forest where most scaup nest (Trauger 1971, Grand 1995, Fournier and Hines 2001, Brook 2002 because of logistical difficulties of working in this remote region.…”

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confidence: 99%

Lesser Scaup Nest Success and Duckling Survival on the Yukon Flats, Alaska

et al. 2007

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Over the last 20 years scaup numbers have declined, and these declines have been greatest in the northern boreal forests of Canada and Alaska where most lesser scaup (Aythya affinis) nest. We studied nest success and duckling survival of lesser scaup over 3 field seasons, 2001–2003, on the Yukon Flats National Wildlife Refuge in northeastern Alaska, USA. Daily survival rate (DSR) of nests on our study area across all 3 years was 0.943 (n = 177 nests, 95% CI: 0.930–0.954), corresponding to a nest success of only 12.3%, considerably lower than published estimates of an average nest success as high as 57% for lesser scaup in the northern boreal forest. With Mayfield logistic regression, we investigated effects on nest survival of year, clutch initiation date, and nesting habitat type (large wetlands >10 ha, small wetlands <10 ha, and wooded creeks). Neither year nor clutch initiation date influenced nest survival; however, the odds of nest success on large wetlands was 49% lower than on wooded creeks (odds ratio = 0.512, 95% CI = 0.286, 0.918). Based on the model that used only habitat type for estimation, DSR on large wetlands was 0.931 (corresponding nest success = 7.6%), DSR on small wetlands was 0.941 (nest success = 11.1%), and DSR on wooded creeks was 0.963 (nest success = 26.2%). To estimate duckling survival, we monitored 10 broods (n = 75 ducklings) over 3 field seasons by radiotagging hens at nest hatch. Most duckling mortality (94%) occurred in the first 10 days after hatch. Average duckling survival during 1–10 days was 0.321 (95% CI: 0.122–0.772), during 11–20 days was 0.996 (95% CI: 0.891–1.040), and during 21–30 days was 0.923 (95% CI: 0.769–1.041). Three of 10 hens moved all or part of their broods overland between nesting and brood‐rearing wetlands for distances of 0.3–1.6 km. Our estimates of lesser scaup nest success and duckling survival on the Yukon Flats were among the lowest ever reported for ducks nesting at northern latitudes, even though the study site was in pristine boreal forest. Estimating and comparing scaup demographic rates from different geographic areas can contribute to improved conservation. Given the scarcity of information on scaup nesting in the boreal forest, basic nesting parameters are important to those trying to model scaup population dynamics.

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“…Using iris color, Trauger (1974a) identified the range of eye coloration in female lesser scaup (Aythya affinis) from yearlings to 5-year-olds. Although an increase in vermiculation with age is clearly evident in canvasbacks, inadequate samples of known-age 4-year-old and older birds prevented further analysis in our study.…”

Section: Discussionmentioning

confidence: 99%

“…The ability to recognize age-classes within a population is important in understanding aspects of reproductive biology and population dynamics (Trauger 1971, Johnson 1978, Krapu and Doty 1979, Raveling 1981. Due to the low population status of the canvasback in recent years, the influence of breeding age on individual productivity has been of concern (Olson 1964, Trauger 1974b, Bellrose 1976.…”

mentioning

confidence: 98%