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

Abstract

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

Annual survival in female white‐winged scoters and lesser scaup

“…For scaup, eye color (Trauger ) indicated that our decoy‐trapped females were on average younger than nest‐trapped birds (S. M. Slattery, unpublished data), consistent with previous findings of decoy trap bias toward younger or poorer quality individuals (Weatherhead and Greenwood , Fast et al ). In addition, we detected evidence of subsequent nesting in only a few decoy‐trapped scaup in the year of trapping (S. M. Slattery, unpublished data), much like Martin et al (). If true, these inexperienced females may be on the breeding grounds prospecting for potential future breeding sites, so fidelity to a breeding site may not yet be established.…”

“…Like annual survival, breeding season survival estimates for scaup at Cardinal Lake were like those observed during the same portions of the breeding season at both boreal and parkland-breeding areas (Table 4). However, these values differed markedly from those of Martin et al (2009) who attributed higher survival of female scaup in Alaska to low breeding propensity, and Koons and Rotella (2003), who implied that lower female survival of parkland scaup may have been due to high mink (Neovison vison) predation during a longer nesting season than typically encountered in the far north. Across multiple studies, between 23% and 63% of annual female scaup mortality occurred during the breeding season ( Table 4), most of which likely occurred during nesting when females are more susceptible to predation Rotella 2003, Bond et al 2009).…”

Wetland food resources for spring‐migrating ducks in the Upper Mississippi River and Great Lakes Region

“…Late winter and early spring represent a critical time period, as the physical condition of ducks during this time can influence breeding effort (Anteau and Afton 2004, Arzel et al 2006). Although the relationship among spring food resource, body condition, and breeding success has been somewhat equivocal for ducks and varies among species (i.e., capital vs. income breeders; see Bonnet et al 1998), recent studies have demonstrated associations between reproductive performance and habitat conditions during spring migration (Newton 2006, Devries et al 2008, Martin et al 2009). Devries et al (2008) showed that female mallards ( Anas platyrhynchos ) arriving on breeding grounds with more nutrient reserves had greater nesting propensity, clutch sizes, and earlier nest initiation and hatch dates compared to females on breeding grounds with fewer nutrient reserves.…”

Reproductive Rates in Lesser Scaup (<i>Aythya affinis</i>) in Southwestern Manitoba: Another Look at the Data

“…For boreal breeding scaup, historical nutrient reserve data are sparse (body mass only; Trauger 1971) but lipid reserves of boreal females measured during [2003][2004] in northern Alberta and the Northwest Territories were much lower than historical values reported for females in northwestern Minnesota in 1986-1988and southwestern Manitoba in 1977-1980(Anteau and Afton 2004, 2009a; but see DeVink et al 2008c). Furthermore, recent studies have reported that some reproductive parameters, such as nest success, female survival, duckling and brood survival, and breeding probability, were low in boreal and parkland breeding sites, at rates that would be consistent with the SCH (Fournier and Hines 2001;Brook 2002;Koons and Rotella 2003;Corcoran et al 2007;Martin et al 2009). Afton and Anderson (2001) and Anteau and Afton (2009a) speculated that reduced food resources at nonbreeding areas would affect body condition and, hence, recruitment of northern boreal breeders more than southern prairie-parkland breeders because of the shorter time between arrival and egg-laying in the north.…”