Josef K. Schmutz

Is the decline of Burrowing Owls Speotyto cunicularia in prairie Canada linked to changes in Great Plains ecosystems

We examined population and ecosystem patterns hoping to inform conservation strategies for Burrowing Owls Speotyto cunicularia in Canada. The owls chose moderately to heavily grazed grasslands for nesting and roosting, and avoided cultivated fields. Where grassland patches were isolated in 90% cultivation, owls dispersed later, for shorter distances and less often. Mortality rate during the 5-month study was high (adult ratio 0.45, juveniles 0.55), which may contribute to local declines. Additional mortality may occur on migration and during winter. We extrapolate from local effects (loss of grassland habitat with burrows for roosting, and ~2% “incidental” predation) to suggest that such changes detrimental to the owls occur throughout the central Great Plains ecosystem which the owls occupy year-round. The changes include ecosystem processes such as plant succession, owl dispersal and predation. These changes are likely to be irreversible on a scale that would be required to help this owl. The species may face extinction in Canada, at the northern limit of its range.

Inheritance of Color Phases of Ferruginous Hawks

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Demography of Ferruginous Hawks Breeding in Western Canada

Abstract We assessed age-dependent survival, site-fidelity, and, together with data on prey and reproduction, trends in the population of ferruginous hawks (Buteo regalis) breeding in western Canada. Our analysis included 7,129 ferruginous hawks banded near Hanna, Alberta, and Kindersley-Alsask, Saskatchewan, from 1972 to 2003. We estimated annual adult survival rate to be 0.708 (SE = 0.024) and first year survival for nestlings was 0.545 (SE = 0.147). Resighting probability was modeled as a constant for nestlings (0.009, SE = 0.010), but it varied among years for adults consistent with our sampling efforts. Band reporting rate was at 0.022 (SE = 0.007) for both nestlings and adults. Fidelity to the study site was 1.00 (SE = 0.000) for adults and 0.035 (SE = 0.014) for nestlings. Nesting density ranged from 3.1 to 14.0 pairs/100 km2 and averaged 9.8 pairs/100 km2. We observed an average clutch size of 3.2 (SE = 0.06) and brood sizes of 2.71 (SE = 0.07) near Hanna and 2.79 (SE = 0.99) at Kindersley-Alsask. Richardsons ground squirrels (Spermophilus richardsonii) made up 95% of ferruginous hawk prey. Prey availability was positively correlated with number of offspring near Hanna and Kindersley-Alsask. We believe the lower than expected adult survival did not result in population decrease; rather, declines in reproduction resulting from declines in the abundance of ground squirrels better explain an observed 4.5-fold decline in nesting densities during the study. The results suggest that ferruginous hawk management should address prey in addition to habitat management, and that management needs are regional in scope with particular emphasis on the breeding range within the northern Great Plains.

Demography of Swainson's Hawks Breeding in Western Canada

Abstract Our objective was to estimate demographic parameters and population trends for Swainsons hawks (Buteo swainsoni) breeding in southeast Alberta and southwest Saskatchewan, Canada, from 1972 to 2003. We assembled mark–resighting–recovery histories of 6,606 banded Swainsons hawks for a joint analysis of survival and resighting probability, including band-reporting rate and fidelity of animals, following Burnhams joint resighting–recovery model provided in program MARK. Our best-fitting survival model specified age-related variation in survival, resighting probability, and fidelity, and it specified age-by-temporal variation in nestling survival and adult resighting probability. From estimated survival rates and previously published data on reproduction, for the period 1973–1996 we estimated the populations finite rate of increase, λ, to be 0.996 (95% CI: 0.945–1.057). We believe that population limitation of Swainsons hawks is primarily related to the influence of prey availability on brood size and nestling survival. Despite indications of recent population declines, we conclude that Swainsons hawks breeding in western Canada are not currently in need of special management action.

Apparent survival of adult Burrowing Owls that breed in Canada is influenced by weather during migration and on their wintering grounds

ABSTRACT Understanding factors that influence the survival of endangered migratory species is critical for making informed management decisions, yet this understanding relies on long-term recapture datasets for species that are, by definition, rare. Using 3 geographically widespread (Saskatchewan, Alberta, and Manitoba, Canada) and long-term (6–15 yr) mark–recapture datasets, we quantified spatial and temporal variation in apparent annual survival and recapture probabilities of Burrowing Owl (Athene cunicularia), an endangered species that breeds in Canada. We then examined how large-scale weather patterns during migration (storms) and on the wintering and breeding grounds (precipitation), in addition to prey irruptions on the breeding grounds, influenced apparent survival of Burrowing Owls. Female Burrowing Owls had lower apparent survival than males in all 3 study areas. Storms during fall migration and above-average precipitation on the wintering grounds were associated with reduced apparent survival of Burrowing Owls in the longest-running study area, Saskatchewan; in Alberta and Manitoba, there were few correlations between apparent survival of Burrowing Owls and weather or prey irruptions. Increases in stochastic events such as storms during migration or precipitation on the wintering grounds could have adverse consequences on the already small Burrowing Owl population in Canada. Local management actions that focus solely on improving adult apparent survival within Canada are likely insufficient for mitigating susceptibility of adults to inclement weather or other factors outside the breeding season, underscoring the need for management of this species across multiple jurisdictions within North America.

Serum protein polymorphism in common eiders detected by isoelectric focusing.

Some common eider females attend and sometimes care for ducklings of other females (Munro and Bedard, 1977). During a study of female sociality and cooperative nest defense (Schmutz et al., 1982, 1983), we needed to determine genetic relatedness of the cooperative female ducks. Only a few polymorphic proteins have been detected in birds (Matson, 1984), in contrast to mammals. We report here the detection of a new protein polymorphism, using isoelectrofocusing (IEF), in the common eider.