Browsing by Author "Nichols, Theodore C."
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Item A population model for management of Atlantic flyway resident population Canada geese(Wildlife Society Bulletin, 2016-03-28) Beston, Julie A.; Williams, Christopher K.; Nichols, Theodore C.; Castelli, Paul M.Highly abundant resident Canada geese (Branta canadensis) cause property damage throughout their range. Effective reduction and management of these populations requires knowledge of their population dynamics and responses to management actions. We used data from New Jersey, USA, and other resident Canada goose populations to produce stage-structured matrix models for resident Canada geese from both urban and rural landscapes. We ran stochastic simulations to assess 3 management activities for Atlantic Flyway Resident Population Canada geese: harvest, nest treatment, and cull. Unrealistic harvest rates, in excess of 10% for urban geese, would be needed to reduce the urban population to target levels within 10 years in the absence of other management activities. Nest treatment to prevent hatching is less controversial than culling adults, but as many as 62% of eggs in urban areas would need to be treated annually to sufficiently reduce the mean stochastic population growth rate. Cull would be the most effective way to achieve the population goal, but current cull rates are insufficient to reduce the urban population. Although reduction of urban geese was a challenge, current management activities in rural populations appeared to be sufficient to reduce populations. We also provide a simple spreadsheet tool for managers who want to explore management options for other resident Canada goose populations by inserting relevant vital rate estimates for their populations and manipulating management activities. © 2016 The Wildlife Society.Item Estimating Waterfowl Carrying Capacity at Local Scales: A Case Study From Edwin B. Forsythe National Wildlife Refuge, New Jersey(Journal of Fish and Wildlife Management, 2018-01-29) Ringelman, Kevin M.; Williams, Christopher K.; Castelli, Paul M.; Sieges, Mason L.; Longenecker, Rebecca A.; Nichols, Theodore C.; Earsom, Stephen D.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, morphometrically corrected for site- and day-specific thermoregulatory costs. To estimate population-level energy demand, we used standardized monthly ground surveys (2005–2014) to create a migration curve, and proportionally scaled that to fit aerial survey data (2005–2014). Crucially, we also explicitly incorporated estimates of variance in all of these parameters and conducted a sensitivity analysis to diagnose the most important sources of variation in the model. Our results from an outlier-removed, a strict depletion model indicated that at estimated mean levels of supply (923 million kcal) and cumulative demand (3.4 billion kcal), refuge food resources were depleted before November. However, a constant-supply model that represented tidal replenishment of resources indicated that just enough energy was present to sustain peak winter populations. Variation in model output appeared to be driven primarily by uncertainty in population abundance during peak periods of use, emphasizing a new management focus on studying migration chronologies of waterfowl. This model allows for relative assessment of biases and uncertainties in carrying-capacity modeling, and serves as a framework identifying critical science needs to improve local and regional waterfowl management planning.Item Evaluation of a clutch-containment method during hatch in geese: Using resident Canada geese as an example(Wildlife Society Bulletin, 2012-04-10) Guerena, Katherine B.; Castelli, Paul M.; Nichols, Theodore C.; Williams, Christopher K.Disruption associated with nest visits during the hatch period of waterfowl can cause partial abandonment of hatchlings, potentially causing bias in the survival of marked birds. We evaluated the use of a mesh clutch-containment bag to capture and mark entire broods of 151 resident Canada goose (Branta canadensis) nests, prior to hatch, while minimizing observer-caused disruption during brooding. The study was conducted in New Jersey, USA, from April to June 2010. No differences were found in hatch success or the number of hatchlings marked between contained clutches and the control group. Although this technique was not beneficial in studying gosling survival in temperate nesting populations, it may be effective in sub-Arctic nesting conditions where nest visits are conducted using a more invasive approach such as a helicopter. © 2012 The Wildlife Society.Item Spatially-explicit land use effects on nesting of Atlantic Flyway resident Canada geese in New Jersey(Wildlife Biology, 2014-04-01) Guerena, Katherine B.; Castelli, Paul M.; Nichols, Theodore C.; Williams, Christopher K.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.Item Survival and harvest of Atlantic Flyway resident population Canada Geese(Wildlife Society Bulletin, 2015-07-24) Beston, Julie A.; Williams, Christopher K.; Nichols, Theodore C.; Castelli, Paul M.Resident Population Canada geese (Branta canadensis) are a valuable natural resource, but at high densities they create problems by colliding with vehicles, damaging crops, and fouling parks with feces. Effective management of these geese could be improved with knowledge of demographic rates, especially survival. We used band recovery data from 2005 to 2012 to estimate temporally and spatially explicit survival and recovery rates of Atlantic Flyway Resident Population Canada geese. We analyzed the data in Program MARK and found evidence that survival and recovery varied by age, state of banding, and year. We present state–age–year survival, recovery, and harvest rates from all states. Model-averaged estimates of adult survival ranged from 0.62 to 0.87 and had high precision for most states. Estimates of survival of juvenile geese were generally higher than those for adult geese, but they were less precise and more variable among states. Based on estimates of survival and recovery rates, the average annual harvest rate of adult geese was 13.5% and ranged from 3.1% in North Carolina to 20.1% in Pennsylvania, USA. Harvest rates of juvenile geese were not significantly different from those of adult geese and averaged 15.3%. The estimated survival and harvest rates can be incorporated into population models to assess potential effectiveness of various management strategies for Resident Population Canada geese. © 2015 The Wildlife Society.