Lesser Scaup Population Dynamics: What Can Be Learned from Available Data?

Koons, David N.; Rotella, Jay J.; Willey, David W.; Taper, Mark L.; Clark, Robert G.; Slattery, Stuart M.; Brook, Rodney W.; Corcoran, Robin M.; Lovvorn, James R.

doi:10.5751/ace-00105-010306

Cited by 44 publications

(54 citation statements)

References 36 publications

(69 reference statements)

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“…Across multiple studies, between 23% and 63% of annual female scaup mortality occurred during the breeding season (Table ), most of which likely occurred during nesting when females are more susceptible to predation (Koons and Rotella , Bond et al ). Thus, these results reinforce the importance of breeding season events on population dynamics in scaup (Koons et al , ).…”

Section: Discussionsupporting

confidence: 85%

“…Sea duck species like scoters tend to be relatively long lived (Krementz et al ) and adult survival could have a profound effect on population dynamics, as reported for lesser and greater ( A . marila ) scaup (Flint et al , Koons et al ) and some sea duck species (Mallory ). Thus, filling gaps for these species about sources of variation in adult female survival will provide information about the components that may be controlled by management.…”

Section: Global Climate Indices Anticipated Ecological Effects In Wimentioning

confidence: 99%

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Annual survival in female white‐winged scoters and lesser scaup

Slattery

Clark

2019

J Wildl Manag

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Quantifying survival and understanding underlying sources of variation are important for developing population models and informing management decisions. We estimated apparent survival (i.e., true survival less permanent emigration) for adult female white‐winged scoters (Melanitta fusca) and lesser scaup (Aythya affinis) breeding at a northern boreal forest site in western Canada, 2002–2008. We also evaluated variation in survival relative to indices of breeding status, individual quality, spring weather conditions, local small‐mammal abundance, and overwinter climate. Breeding female scoters had higher apparent survival than did nonbreeding females, suggesting that breeders had higher survival or fidelity to the study area, or that more nonbreeders were transient birds that may have bred elsewhere in subsequent years. Apparent survival rate for breeding female scoters was unrelated to other individual and environmental covariates. Nest‐trapped female scaup had higher apparent survival rates than did prenesting females captured in decoy traps, implying that more pre‐nesters dispersed permanently or died after marking. Nesting female scaup with higher body condition or those in years when small mammals were more abundant had higher apparent survival; associations between survival and other environmental covariates were less certain. Overall, apparent survival rate of breeding adult female scoters was lower than reported for scoters from other North American locations or for other sea duck species, whereas estimates for nesting female scaup were comparable with those from other boreal and prairie‐parkland locations. Our results indicate that for scaup in this region, factors influencing female body condition, such as maintaining high‐quality habitat, areas with abundant food or low disturbance, could improve annual survival. © The Wildlife Society, 2019

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Section: Discussionsupporting

confidence: 85%

Section: Global Climate Indices Anticipated Ecological Effects In Wimentioning

confidence: 99%

Annual survival in female white‐winged scoters and lesser scaup

Slattery

Clark

2019

J Wildl Manag

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“…Our current population models, based on limited data for Boreal-breeding birds, suggest that scaup population dynamics are highly responsive to changes in adult female non-breeding (and breeding) season survival and to a lesser extent on variation in nest and duckling survival rates [40]. If low productivity is more prevalent now than it was historically, it will be important to know whether proposed hunting restrictions for scaup will increase adult and juvenile survival rates to levels that offset this lower production.…”

Section: Discussionmentioning

confidence: 97%

A Method for Investigating Population Declines of Migratory Birds Using Stable Isotopes: Origins of Harvested Lesser Scaup in North America

et al. 2009

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BackgroundElucidating geographic locations from where migratory birds are recruited into adult breeding populations is a fundamental but largely elusive goal in conservation biology. This is especially true for species that breed in remote northern areas where field-based demographic assessments are logistically challenging.Methodology/FindingsHere we used hydrogen isotopes (δD) to determine natal origins of migrating hatch-year lesser scaup (Aythya affinis) harvested by hunters in the United States from all North American flyways during the hunting seasons of 1999–2000 (n = 412) and 2000–2001 (n = 455). We combined geospatial, observational, and analytical data sources, including known scaup breeding range, δD values of feathers from juveniles at natal sites, models of δD for growing-season precipitation, and scaup band-recovery data to generate probabilistic natal origin landscapes for individual scaup. We then used Monte Carlo integration to model assignment uncertainty from among individual δD variance estimates from birds of known molt origin and also from band-return data summarized at the flyway level. We compared the distribution of scaup natal origin with the distribution of breeding population counts obtained from systematic long-term surveys.Conclusions/SignificanceOur analysis revealed that the proportion of young scaup produced in the northern (above 60°N) versus the southern boreal and Prairie-Parkland region was inversely related to the proportions of breeding adults using these regions, suggesting that despite having a higher relative abundance of breeding adults, the northern boreal region was less productive for scaup recruitment into the harvest than more southern biomes. Our approach for evaluating population declines of migratory birds (particularly game birds) synthesizes all available distributional data and exploits the advantages of intrinsic isotopic markers that link individuals to geography.

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“…Population models based on meta-analyses are useful learning tools, but they confound spatial and temporal variation, which limits guidance for management actions that are directed at specific populations (Morris and Doak 2002, Koons et al 2006, Taylor et al 2012. Here, we used data from one of the longest continuous studies of sage-grouse demography to evaluate both retrospective and prospective vital-rate contributions to the dynamics of a population to determine the most important vital rates for conservation efforts (Caswell 2000, Dobson andOli 2001), and to assess whether current trends in management of this candidate species may need to be reevaluated.…”

Section: Introductionmentioning

confidence: 99%

Evaluating vital rate contributions to greater sage‐grouse population dynamics to inform conservation

et al. 2016

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Abstract. Species conservation efforts often use short-term studies that fail to identify the vital rates that contribute most to population growth. Although the greater sage-grouse (Centrocercus urophasianus; sage-grouse) is a candidate for protection under the U.S. Endangered Species Act, and is sometimes referred to as an umbrella species in the sagebrush (Artemisia spp.) biome of western North America, the failure of proposed management strategies to focus on key vital rates that may contribute most to achieving population stability remains problematic for sustainable conservation. To address this dilemma, we performed both prospective and retrospective perturbation analyses of a life cycle model based on a 12-yr study that encompassed nearly all sage-grouse vital rates. To validate our population models, we compared estimates of annual finite population growth rates (λ) from our female-based life cycle models to those attained from male-based lek counts. Post-fledging (i.e., after second year, second year, and juvenile) female survival parameters contributed most to past variation in λ during our study and had the greatest potential to change λ in the future, indicating these vital rates as important determinants of sage-grouse population dynamics. In addition, annual estimates of λ from female-based life cycle models and malebased lek data were similar, providing the most rigorous evidence to date that lek counts of males can serve as a valid index of sage-grouse population change. Our comparison of fixed and mixed statistical models for evaluating temporal variation in nest survival and initiation suggest that conservation planners use caution when evaluating short-term nesting studies and using associated fixed-effect results to develop conservation objectives. In addition, our findings indicated that greater attention should be paid to those factors affecting sage-grouse post-fledging females. Our approach demonstrates the need for more long-term studies of species vital rates across the life cycle. Such studies should address the decoupling of sampling variation from underlying process (co)variation in vital rates, identification of how such variation drives population dynamics, and how decision makers can use this information to re-direct conservation efforts to address the most limiting points in the life cycle for a given population.

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Lesser Scaup Population Dynamics: What Can Be Learned from Available Data?

Cited by 44 publications

References 36 publications

Annual survival in female white‐winged scoters and lesser scaup

Annual survival in female white‐winged scoters and lesser scaup

A Method for Investigating Population Declines of Migratory Birds Using Stable Isotopes: Origins of Harvested Lesser Scaup in North America

Evaluating vital rate contributions to greater sage‐grouse population dynamics to inform conservation

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