No abstract

Growth of temperate breeding Canada goose (Branta canadensis maxima) populations remains a challenge for agencies that seek to balance social acceptance with demand for hunting opportunity from constituents. Harvest regulation is the principle means by which federal and state agencies attempt to keep populations in balance with their environment. Band recovery data and aerial surveys are used to monitor populations and evaluate population control efforts. Greater than 140,000 temperate‐breeding Canada geese were banded in Ohio, USA, from 1990 to 2015. We used Brownie dead‐recovery models to estimate survival rates as a function of time, age, urban–rural status, winter weather severity, and hunting regulations. We derived annual direct‐recovery rates by age and urban–rural cohorts. We mapped all recoveries of Ohio‐banded geese to investigate changes in harvest distribution over time. The highest‐ranked model that explained survival of Ohio‐banded geese had urban–rural status, age, and winter weather severity effects. Survival rates were lower during severe winters for adult rural geese, adult urban geese, and hatch‐year urban geese; however, hatch‐year rural geese had greater survival rates during severe winters. Direct recovery rates of all geese remained stable over the duration of the study (1990–2015), and there was a shift eastward in distribution of band recoveries over time. Survival rates of Ohio‐banded Canada geese appear to be largely unaffected by annual harvest regulations. Furthermore, long‐term moderation of winter weather in Ohio could result in increased adult goose survival, requiring additional management actions to temper population growth. © 2018 The Wildlife Society.

I studied muskrat (Ondatra zibethicus) populations in response to a partial (30 cm) late summer drawdown in the Saskatchewan River Delta, Manitoba, Canada, 2007 through 2009. I conducted house counts from airboats in 2008, 2009, and 2010 to assess house density. I live trapped muskrats in 2008 and 2009 to estimate population size, using closed population models, and to assess muskrat density and body condition. I assessed body condition in 2009 using three techniques, body condition indices (BCIs), hematocrit, and neutrophil to lymphocyte (N/L) quotients. Muskrat house densities were lower partial drawdown (PD) wetlands than full supply level (FSL) wetlands one year following the drawdown. Conversely, muskrat densities, derived from mark-recapture sampling, showed no indication of reduced population densities in PD wetlands. BCIs were unaffected by the partial drawdown, and the ANOVA model constructed to test for differences in hematocrits was not significant indicating no differences between treatments. N/L quotients were higher in PD wetlands, and in the spring indicating the partial drawdown and overwinter conditions may have induced physiological stress. floating vegetation condition. Active house locations were positively correlated with distance to upland and water depth, and negatively correlated with distance to open water and greenness of vegetation index. Typha spp. had the lowest ADF content and the highest CP content. The floating and rooted conditions of Typha spp. did not differ significantly in ADF or CP. The partial drawdown did not significantly affect ADF or CP in the emergent vegetation species that were sampled.

Grassland birds have declined throughout North America. In the midwestern United States, reclaimed surface mines often provide expanses of contiguous grassland that support grassland birds. However, some reclaimed surface mines often experience severe woody vegetation encroachment, typically by invasive trees and shrubs, including black locust Robinia pseudoacacia, autumn olive Elaeagnus umbellata, and bush honeysuckle Lonicera spp. We conducted point-count surveys to investigate the effects of woody canopy cover and response to treatments of woody vegetation on the abundance of birds. Our treatments were a control, an herbicide application, and an herbicide application followed by cutting and shredding of standing dead woody vegetation. Estimated density of eastern meadowlark Sturnella magna, grasshopper sparrow Ammodramus savannarum, and Henslow's sparrow Centronyx henslowii was 670%, 958%, and 200%, respectively, greater on areas treated with herbicide and shredding and 279%, 666%, and 155%, respectively, greater on areas treated with herbicide-only when compared with control sites. When woody canopy cover increased from 0% to 20%, densities of eastern meadowlark, grasshopper sparrow, and Henslow's sparrow decreased by 83.9%, 74.9%, and 50.7%, respectively. Conversely, densities of eastern towhee Pipilo erythrophthalmus, prairie warbler Setophaga discolor, yellow-breasted chat Icteria virens, and yellow warbler Setophaga petechia increased 67.4%, 57.0%, 34.6%, and 117.7%, respectively, as estimated woody canopy coverage increased from 20% to 60%. Our results showed treating encroaching woody vegetation on reclaimed surface mines with herbicide and shredding increases available habitat used by grassland birds. Maintaining grasslands on reclaimed surface mines at ≤10% woody canopy coverage would be most beneficial to eastern meadowlarks, grasshopper sparrows, and Henslow's sparrows.