Date of Award:

1998

Document Type:

Thesis

Degree Name:

Master of Science (MS)

Department:

Natural Resources

Department name when degree awarded

Fisheries and Wildlife

Advisor/Chair:

John A. Bissonette

Abstract

Canada geese (Branta canadensis) recently have become management problems in some areas due to overpopulation At Fish Springs National Wildlife Refuge (NWR). managers are concerned with the opposite situation Despite attempts to boost production, only 18 to 34 goslings of the western Canada goose (B. c. moffitti) were produced per year, from 1989 to 1993. I studied the breeding population from March to July in 1996 and 1997. Results suggest that production is limited in 3 ways: low gosling survival. low nesting success for ground nests, and low number of breeding pairs Gosling survival to fledging was 25% in 1996 and 52% in 1997. I examined the potential causes of low gosling survival, especially the effects of saline drinking water. Specific conductivities in the spring-fed marshes of the desert refuge range from 3.0 to 25.0+ μS/cm. conducted an experiment on captive wild-strain goslings. Three groups received different levels of saline \\ater as measured by specific conductivity: control (0 63 μS/cm), intermediate 12.0 ~1Slcm). and high (18.0 ~1Slcm) I found mortality only at the high level Effects on growth were growth were evident at both the intermediate and high levels, although statistically significant only at the high level. To examine the effects of saline drinking water on survival of free-ranging wild goslings, I collared and radio marked breeding adults, then monitored brood location and gosling numbers. I found that mortality was independent of specific conductivity levels on the brood-rearing impoundments. Observations suggest that the primary causes of low gosling survival involve predation and human disturbance. l compared my results lo the results of other studies. Accuracy of results appears to be related to the estimation technique used. Radio tracking of broods has the potential to be very accurate. Al Fish Springs NWR. l monitored nesting pairs. nests, and broods throughout the breeding season. Ground nests had lower nesting success in both years (56%: 41 %) than artificial nesting platforms (90%, 83%). The number of nesting pairs was 26 and 34 in 1996 and 1997, respectively. Based on these results, l made several management recommendations, including installing more artificial nesting platforms. and minimizing human disturbance.

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