Date of Award:

5-1969

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Wildland Resources

Department name when degree awarded

Wildlife Biology

Committee Chair(s)

J. B. Low

Committee

J. B. Low

Committee

A. W. Stokes

Committee

W. T. Helm

Abstract

Results of past studies on the spring-fed salt marshes of Utah indicated that waterfowl production on these areas was much lower than on Utah's river-fed marshes. Waterfowl production on the newly-established Fish Springs National Wildlife Refuge, a spring-fed marsh, increased considerably, however, after its waters were impounded. It was believed that by determining what caused this increased production at Fish Springs it would be possible to obtain greater waterfowl production at other spring-fed marshes. Consequently waterfowl populations and factors affecting waterfowl production on this marsh were studied during the summers of 1966, 1967, and 1968.

Populations of breeding ducks averaged approximately 900 pairs a year in 1967 and 1968. Mallards, cinnamon teal, and redheads comprised about 80 percent of these birds. Nesting densities, on plots representing available habitat, averaged about one nest per acre during these two years.

In 1967 and 1968 a total of 312 duck nests representing 10 species were studied and their fates determined. Overall nest success was 63 percent, and predators, principally coyotes and striped skunks, destroyed 25 percent of all nests.

Calculated duckling mortality rates during 1967 and 1968, respectively, were 19 and 16 percent. Duck production at Fish Springs averaged about 3,000 birds or about 430 ducks per square mile of marsh habitat a year during this period.

At present the sparsity of adequate nesting cover for gadwalls appears to be an important limitation to breeding by this species at Fish Springs. Nesting cover apparently has not limited the use of this marsh by other waterfowl species, however, as evidenced by a high incidence (76 percent) of nesting on dry ground by redheads and ruddy ducks.

Aquatic insect sampling in waters inundating portions of the original Fish Springs marsh indicated that these waters produced large quantities of proteinaceous foods for ducklings. Populations of aquatic insects in the original marsh were probably low except in recently disturbed areas.

It appears that limitations of brood-rearing habitat were primarily responsible for low waterfowl production in the past. Newly-created impoundments, rich in animal food, were probably the key to the increase in waterfowl production on this marsh.

Checksum

3f3e48418f0c3fc128fbe7b13a132d91

Download

Included in

Biology Commons

Share

COinS

Copyright for this work is retained by the student. If you have any questions regarding the inclusion of this work in the Digital Commons, please email us at .