Isolation of Cryptococcus laurentii from Canada Goose guano in rural upstate New York

Cryptococcus neoformans and Cryptococcus gattii are etiologic agents of cryptococcal pneumonia and meningitis, potentially lethal syndromes associated with AIDS. A related species, Cryptococcus laurentii, has recently been implicated in several cases of human disease. Guano from Canada Goose (Branta canadensis), an organism that lives closely beside man and inhabits recreational space in rural and suburban areas, might be a significant environmental reservoir of Cryptococcus organisms in non-urban areas. Cryptococcal organisms were isolated from Canada Goose guano from a site in rural northern New York, with identification based upon colony and microscopic morphology, ability to metabolize l-Dopa to melanin, and positive reaction with a commercial anti-cryptococcal capsular polysaccharide latex bead agglutination test. DNA sequences from five positive isolates were identical to each other, and identical to the ITS1-5.8S-ITS2 sequences of C. laurentii strain CBS7140 (Accession AY315665) across a 511 bp sequence. All five isolates of C. laurentii possess three of the known virulence factors common to cryptococcal organisms that cause human disease: capsule, ability to grow at 37 °C, and laccase activity.     

The effects of anthropogenic alteration of nesting habitat on rates of extra‐pair fertilization and intraspecific brood parasitism in Canada Geese Branta canadensis

Parentage studies have shown that alternative reproductive strategies are widespread in many avian taxa that were once thought to be monogamous. Recent anthropogenically mediated habitat change may have disrupted ecological factors, such as breeding density, which have given rise to inter‐ and intraspecific variation in the frequency of extra‐pair fertilization (EPF) and intraspecific brood parasitism (IBP). We used genetic analyses to quantify the incidence of alternative reproductive strategies exhibited within clutches of Canada Geese Branta canadensis maxima nesting in high‐ and low‐density situations in and around urban areas in southern Michigan, USA. We tested the hypothesis that high nesting density would increase the frequency of EPF and IBP. There were no significant differences in rates of EPF and IBP clutches (14 and 26% of clutches, respectively) from nests in high‐density (21.7% EPF, 21.7% IBP) vs. low‐density (5.3% EPF, 31.6% IBP) areas, although high‐density sites had a fourfold higher rate of EPF. Rates of EPF and IBP in high‐density urban areas in Michigan were comparable to rates observed in other species nesting under different ecological conditions. Levels of relatedness between host and parasitic females were higher than expected by chance, suggesting that related females are more tolerant of one another and that host females could gain inclusive fitness benefits from rearing parasitic offspring. Our study highlights the importance of understanding the different costs and benefits associated with alternative behavioural repertoires that may vary as habitats and associated selection pressures are increasingly modified by human activities.     

Cultural inheritance drives site fidelity and migratory connectivity in a long-distance migrant

Cultural transmission is thought to be a mechanism by which migratory animals settle into habitats, but little evidence exists in wild populations because of the difficulty of following individuals over successive generations and wide geographical distances. Cultural inheritance of migration routes represents a mechanism whereby geographical isolation can arise between separate groups and could constrain individuals to potentially suboptimal sites within their range. Conversely, adopting the parental migratory route in adult life, rather than dispersing randomly, may increase an individual's reproductive success because that strategy has already been proven to allow successful breeding. We combined a pedigree of related light-bellied Brent geese (Branta bernicla hrota) with 6 years of observations of marked birds to calculate the dispersal distances of adult offspring from their parents in both Ireland and Iceland. In both countries, the majority of offspring were found to recruit into or near their parental sites, indicating migratory connectivity in the flyway. Despite this kin structure, we found no evidence of genetic differentiation using genotype data from 1127 individuals across 15 microsatellite loci. We suggest that the existence of migratory connectivity of subpopulations is far more common than previous research indicates and that cultural information may play an important role in structuring reproductive isolation among them.     

Constraint versus restraint in the body mass dynamics during moult of a species with precocial young

Body mass declines during wing moult in numerous, but not all, populations of Anatidae. We assessed two leading hypotheses for body mass dynamics during wing moult: (1) body mass dynamics are adapted to attain a target body mass at the end of wing moult (restraint hypothesis) vs. (2) body mass dynamics reflect environmental constraint on the nutrient–energy balance during wing moult (constraint hypothesis). We used regressions of mass of breeding female Black Brant Branta bernicla nigricans on ninth primary length (a measure of moult stage) for each of 16 years to assess mass dynamics during wing moult and used regression equations to predict mass at the beginning and end of wing moult each year. We also included gosling mass at 30 days (an indicator of forage availability) in models of adult mass to assess how mass dynamics varied as a function of foraging conditions. Predicted body mass (± 95% CI) at the start of wing moult (ninth primary = 0 mm) varied significantly among years from 1032 ± 52 to 1169 ± 27 g. Similarly, predicted mass in late wing moult (ninth primary = 142 mm) ranged from 1048 ± 25 to 1222 ± 28 g. The rate of mass gain was significantly related to gosling mass at 30 days: interaction between adult ninth primary length and gosling mass = 0.0031 ± 0.0020 (P = 0.003). Females initiated wing moult at lower body masses, gained mass more rapidly and ended with wing moult heaviest when goslings were heaviest. Body mass dynamics of female Black Brant during wing moult were consistent with the constraint hypothesis. The positive association between gosling mass and rate of body mass gain by adult females during wing moult was also consistent with the constraint hypothesis.     

Moulting season corticosterone correlates with winter season bodyweight in an Arctic migrant bird

In vertebrates, the endocrine system translates environmental changes into physiological responses on which natural selection can act to regulate individual fitness and, ultimately, population dynamics. Corticosterone (CORT) and dehydroepiandrosterone (DHEA) are important regulators of the avian endocrine system but relatively few studies have investigated their downstream effects on key morphological fitness‐related traits in free‐living populations. This study quantified endocrine–morphology relationships in free‐living Greenland Barnacle Geese Branta leucopsis that breed in the high Arctic. CORT and DHEA were extracted from feather and blood samples and tested for relationships with three morphological traits associated with survival and reproduction: bodyweight, body size and facial plumage coloration. We expected CORT concentration to be higher in birds with less favourable morphological traits (i.e. lighter, smaller and less attractive) and DHEA to be higher in birds with more favourable traits (i.e. heavier, bigger and more attractive). As expected, individuals with higher CORT during the post‐breeding moult (July/August) had significantly lower bodyweight during the following winter (November–April). In contrast, we found no robust DHEA–morphology relationships and no statistically significant relationship between CORT and body size or facial plumage. Overall, this study provides evidence of a negative relationship between CORT and bodyweight extending across different seasons of the annual cycle in a long‐distance migrant. This is of particular interest because bodyweight fluctuates rapidly in response to environmental resources and is closely linked to both survival and reproductive success in this species. Understanding the relationship between CORT and key morphological traits is important because endocrine‐disrupting contaminants in the Arctic increasingly interfere with CORT function in birds, including Barnacle Geese, and based on the results of this study may have consequences for bodyweight regulation.     

Canada Goose Survival and Recovery Rates in Urban and Rural Areas of Iowa,USA

Once extirpated from much of their North American range, temperate-breeding Canada geese (Branta canadensis maxima) have reached high abundance. As a result, focus has shifted from restoration to managing harvest and addressing human-goose conflict. Conflict persists or is increasing in urban areas throughout the Mississippi Flyway. Managers need more information regarding demographic rates to determine how hunting affects geese breeding in urban areas and what management actions may be required to achieve management goals. We estimated survival, dead recovery, live recapture, and fidelity probabilities using data from 77,872 Canada geese banded in Iowa, USA, during 1999–2019 using Burnham joint live-dead band recovery models. Factors predicted to affect parameters in candidate models included age (juvenile, subadult, adult), banding site (urban, rural), time, trend, harvest regulation index, and winter severity index. We predicted Canada geese banded in urban areas would have higher survival and lower dead recovery rates than geese banded at rural sites. The top model indicated support for age and banding site effects, and trends in survival and recovery rate (Brownie parameterization). Adult survival was similar for urban (0.75; range = 0.60–0.92) and rural (0.75; range = 0.66–0.82) geese and relatively constant across years. Mean juvenile survival was lower in urban (0.74; range = 0.48–0.93) than rural (0.85; range = 0.68–0.92) areas. Survival increased for urban-banded juveniles and recovery rates increased during liberalization of harvest regulations and decreased after regulations stabilized. Recovery rates of subadults increased for the urban and rural groups. Our results suggest Canada geese breeding in urban areas contribute to harvest and specialized regulations can affect these populations. Harvest regulations in place during our analysis may not have reached a threshold required to observe substantial changes in survival. Current human-goose conflict in urban areas suggests survival has not decreased to a level required to completely address conflict via reduction in goose abundance. Managers may consider additional liberalization of harvest regulations and monitoring via banding to determine to what degree hunter harvest contributes to reducing human-goose conflict and what additional management actions will be required to achieve goals. © 2020 The Wildlife Society.     

Heterozygosity-fitness correlations in a migratory bird: an analysis of inbreeding and single-locus effects

Studies in a multitude of taxa have described a correlation between heterozygosity and fitness and usually conclude that this is evidence for inbreeding depression. Here, we have used multilocus heterozygosity (MLH) estimates from 15 microsatellite markers to show evidence of heterozygosity-fitness correlations (HFCs) in a long-distance migratory bird, the light-bellied Brent goose. We found significant, positive heterozygosity-heterozygosity correlations between random subsets of the markers we employed, and no evidence that a model containing all loci as individual predictors in a multiple regression explained significantly more variation than a model with MLH as a single predictor. Collectively, these results lend support to the hypothesis that the HFCs we have observed are a function of inbreeding depression. However, we do find that fitness correlations are only detectable in years where population-level productivity is high enough for the reproductive asymmetry between high and low heterozygosity individuals to become apparent. We suggest that lack of evidence of heterozygosity-fitness correlations in animal systems may be because heterozygosity is a poor proxy measure of inbreeding, especially when employing low numbers of markers, but alternatively because the asymmetries between individuals of different heterozygosities may only be apparent when environmental effects on fitness are less pronounced.     

Long-Term Survival and Harvest of Resident Canada Geese in Virginia

Resident populations of Canada geese (Branta canadensis) are of particular management interest throughout the eastern United States given increased human-wildlife conflicts due to regional increases in the Atlantic Flyway Resident Population. Within Virginia, USA, growth rates of resident goose populations have been reduced through extended harvest seasons and increased bag limits. Our objective was to investigate spatiotemporal patterns in survival rates and harvest rates of resident geese in Virginia over the past 25 years. We estimated annual survival, recovery, and harvest rates using mark-recapture data from 1990–2015 for individuals that were banded as resident birds during summer throughout the state. We tested for differences in annual survival probability and harvest rates of resident geese banded and recovered in 3 distinct goose hunt zones: the Atlantic, Southern James Bay, and Western hunt zones, each of which had different hunting regulations. We also tested for differences in survival and harvest rates between individuals banded in rural or urban sampling locations, and between age classes (i.e., after hatch-year or hatch-year). In general, survival rates of resident geese over the past 25 years in Virginia are declining. Differences in survival among the 3 goose hunt zones also suggests that current harvest management strategies have reduced survival rates of resident geese. Upon closer examination, we found differences in survival among zones, with resident geese in the Atlantic and Southern James Bay hunt zones showing more negative declines compared to resident geese in the Western zone. Resident geese banded in rural areas had higher survival than urban-banded geese. We also investigated the effects of sampling effort on survival estimates and found no difference in survival estimates among groups when using 75%, 50%, 25%, or 5% of the data randomly sampled from the full data set, suggesting that banding efforts of resident geese could be reduced and continue to inform adaptive management strategies for these populations throughout Virginia. © 2020 The Wildlife Society.