Paul M. Castelli

Neck bands reduce survival of Canada geese in New Jersey

We examined the effect of neck bands on the survival and recovery rates of Canada geese (Branta canadensis) breeding in New Jersey. A total of 8,082 geese were legbanded and 3,428 geese were neck- and legbanded from 1984 through 1989 during June-July throughout New Jersey. Our analysis suggested that survival rates did not differ between adults and immatures within either group (P > 0.05). However, there was evidence that survival did differ between the 2 methods of marking (P < 0.01). The average annual survival rate was estimated as 82.77% (SE = 3.17%) for geese with leg bands only and 69.21% (SE = 3.66%) for geese banded with both leg and neck bands. The use of neck-band observations to estimate annual or period survival rates requires an assumption that neck bands do not influence survival rates. In our study, this assumption appeared to be violated. Managers should use caution in interpreting the results of existing neck-banding studies. Neck bands should be used judiciously and, when possible, with a leg-banded only control group.

Life on the Edge: Northern Bobwhite Ecology at the Northern Periphery of Their Range

ABSTRACT Over the past 40 years, Northern bobwhite (Colinus virginianus) populations have declined range-wide. The Mid-Atlantic once held the highest densities in the country and now shows some of the worst declines. Although population parameters have been quantified throughout most of the bobwhite range, Mid-Atlantic populations have been largely unstudied. To better quantify the dynamics of this declining system, we sought to not only gather annual data on home range, movement, and habitat selection, but also examine how some of these metrics might impact survival. We captured and radio-tracked 154 bobwhites between May 2006 and April 2008 on a 125 km2 area of Cumberland County, New Jersey, USA. Seasonal daily movement ranged from 146 m to 158 m but several extreme movements were notable. Across seasons, grassland habitat was used in greater proportion to its availability, shrub-scrub and agriculture habitats were used equally with their availability and forests and other habitats were used less than their availability. Differences in second-order selection occurred between seasons with lower use of shrub-scrub and forest habitats and higher use of other habitat in breeding seasons. Pooled breeding season survival was 0.343, nonbreeding season survival was 0.183, and annual survival was 0.063. Although mortality was dominated by avian predators, house cat mortalities were noteworthy. Cox proportional hazard analysis revealed that risk of breeding season mortality risk was increased by longer daily movement, lower grassland use, and higher forest and other use. During the nonbreeding season, risk of mortality increased with shorter daily movement and proximity to occupied buildings and barns. This information could inform management decisions in the greater Mid-Atlantic as well as other areas of their range where they exist at very low abundances.

Distinguishing migratory and resident Canada geese using stable isotope analysis

Effective management of Canada geese (Branta canadensis) requires a reliable method to determine the population affiliation of geese in the harvest. We determined if stable isotope analysis of feather tissue could distinguish between migrant and resident populations. We obtained feather samples of migrants from Atlantic population of Canada geese in northern Quebec near Ungava Bay, Canada. We grouped resident population Canada geese as coastal residents and inland residents according to the habitats where they were captured in New Jersey. We analyzed for isotopes of carbon (δ 13 C), nitrogen (δ 15 N), and sulfur (δ 34 S). We found significant differences among migrants, coastal residents, and inland resident for all 3 isotopes. Combinations of isotopic ratios for the 3 elements resulted in unique patterns among groups of geese. We entered the isotopic ratios into a discriminant analysis using collection site as the grouping variable (migrants, inland residents, and coastal residents). We formed 2 significant functions that discriminated among the 3 groups 92% of the time. The first function accounted for most of the variance, and was highly influenced by the isotope ratios for carbon and sulfur. The results indicate that stable isotope analysis of primary feathers can provide a reliable means to discriminate between migratory and resident populations of Canada geese. Stable isotope analysis is a promising technique for identifying the breeding areas of Canada geese, but additional studies are needed to determine inherent variability over broad geographic areas.

Time Energy Budgets and Food use of Atlantic Brant Across Their Wintering Range

ABSTRACT We conducted extensive behavioral and food sampling of Atlantic brant (Branta bernicla hrota) across their winter range and used time-activity budgets for brant to determine daily energy expenditure (DEE). Sampling occurred 1 December—31 May 2006–2008 in 11,225-km2 sites between Rhode Island and Virginia containing important estuarine and upland habitat. To calculate DEE we used instantaneous scan sampling to estimate time-activity budgets. We also determined foods eaten by brant and energy density of food plants. Last, we quantified body condition of brant, which differed among years, months, regions, and ages, and sexes. Overall DEE for brant was 1,530 ± 64 kJ/day. There was considerable variation in time— activity budgets among years, months, regions, habitat, tide, temperature, and time-of-day, but we detected no significant difference in DEE of brant between years or among regions. However, DEE in January (2,018 ± 173 kJ/day) was nearly double the DEE of brant in May (1,048 ± 137 kJ/day). Brant spent their time feeding (32.3%), swimming (26.2%), resting (16.2%), and flying (14.5%). The percent of brant foreguts sampled contained macroalgae (53%) eelgrass (Zostera marina; 18%), salt marsh cordgrass (Spartina alterniflora; 17%), and terrestrial grass (Poa. sp.) and clover (Trifollium sp.; 9%). Energy density differed by vegetation type: macroalgae (12.6 ± 0.1 kJ/g), eelgrass (14.1 ± 0.1 kJ/g), new-growth salt marsh cordgrass (16.9 ± 0.2 kJ/g), and terrestrial grass and clover (17.7 ± 0.1 kJ/g). Atlantic brant exhibited behavioral plasticity thereby allowing modification of daily activity budgets to meet seasonally varying energetic requirements associated with wintering and spring staging. Recognizing a variable DEE can be used along with eventual estimates of food biomass and total metabolizable energy on the landscape to calculate carrying capacity (goose use days) on state, region, or range-wide scales.

Spatially-explicit land use effects on nesting of Atlantic Flyway resident Canada geese in New Jersey

Atlantic Flyway resident population (AFRP) Canada geese Branta canadensis in New Jersey, USA, have grown dramatically during the last thirty years and are considered as overabundant in many areas. Development of corporate parks and urban areas with manicured lawns and artificial ponds offer ideal nesting habitat for AFRP geese, with limited pressure from hunting or natural predators. As a result, spatial heterogeneity in reproduction must be taken into account in managing the population. We identified the site and landscape spatial scale extents at which land use features influenced nest site selection and nest success. Nest searches were conducted throughout the State during 2009—2010, and 309 nests were monitored through hatch to determine their fates. We ran a spatial correlation analysis of land use composition to identify spatial scale extents at which geese most considerably respond to their environment for nest site selection and nest success. All significant spatial scale extents were at or below 2.25 km for the five classified land use types. We emphasize that habitat-goose associations in densely urban areas were strongest at extents < 1 km, while rural and natural areas were strongest at extents > 1 km. Geese responded to human-dominated land uses at a smaller spatial scale extent than land uses with low human density. The strength of all nest-land use univariate relationships was low; however, our primary objective was to identify the scales extent at which geese associate with land use, rather than the intensity. We encourage managers to consider these scale-dependent associations in identifying important habitat variables in multivariate models; and if population control of AFRP Canada geese is of primary interest, then focusing on local habitat management will most likely have the largest influence in managing this population.

A 24-Hour Time-Energy Budget for Wintering American Black Ducks (Anas rubripes) and its Comparison to Allometric Estimations

Abstract. Previous efforts to estimate the daily energy expenditure of American Black Ducks (Anas rubripes) have relied upon diurnal behavior observations or predictive allometric equations. American Black Duck behavior was quantified during morning crepuscular, diurnal, evening crepuscular and nocturnal periods to create a 24-hr time-energy budget. Behaviors and energy expenditure differed between periods and months, with hourly energy expenditure highest during the morning crepuscular period and lowest during the nocturnal period. Daily energy expenditure estimates based on a 24-hr time-energy budget were lower than estimates calculated from extrapolated diurnal behavioral data as well as a predictive allometric equation that uses a generalized dabbling duck resting metabolic rate. However, there was no difference between the 24-hr time budget and a predictive allometric equation using American Black Duck specific resting metabolic rates. Future researchers and managers should acknowledge the assumptions of each methodology to estimate daily energy expenditure when using a bioenergetic approach to estimate carrying capacity.

Estimating Waterfowl Carrying Capacity at Local Scales: A Case Study from Edwin B. Forsythe National Wildlife Refuge, New Jersey

Abstract The management of wintering North American waterfowl is based on the premise that the amount of foraging habitat can limit populations. To estimate carrying capacity of winter habitats, managers use bioenergetic models to quantify energy (food) availability and energy demand, and use results as planning tools to meet regional conservation objectives. Regional models provide only coarse estimates of carrying capacity because habitat area, habitat energy values, and temporal trends in population-level demand are difficult to quantify precisely at large scales. We took advantage of detailed data previously collected on wintering waterfowl at Edwin B. Forsythe National Wildlife Refuge and surrounding marsh, New Jersey, and created a well-constrained local model of carrying capacity. We used 1,223 core samples collected between 2006 and 2015 to estimate food availability. We used species-specific 24-h time–activity data collected between 2011 and 2013 to estimate daily energy expenditure, morphometric...

Observed Herring Gull Kleptoparasitism of American Black Ducks

Abstract Herring gulls Larus argentatus were observed to kleptoparasitize American black ducks Anas rubripes feeding on fiddler crabs Uca pugnax in coastal New Jersey. Although widespread in Laridae, kleptoparasitism has never been described between these two species. Over two winters of intensive 24-hour behavioral observations, this interaction was observed on two occasions during similar tidal conditions. Although this appears to be a rare interaction with limited energetic consequences, we note that quantifying these uncommon interspecific interactions is a benefit of thorough behavior observations, which may refine estimates of daily energy expenditure.