Date of Award

5-1-1980

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biology

Abstract

Data on the disabled in textbooks revealed that more disabled males than disabled females were visible. More adults including senior citizens were depicted as disabled characters. Sixty-seven percent of the disabilities were physical in origin. Nearly 70 percent of the disabled characters were Caucasian. Characterization and language were generally positive.

Analysis of flock characteristics indicated paired and unpaired gadwall remained partially segregated and that pairs were dominant over unpaired gadwall. Pairs were involved in less agonistic activity and remained at greater distances from other birds than unpaired gadwall. Pairing cnronology and behavior suggested that although pairs arose from temporary associations, pair formation occurred rapidly and by late November 80% of the females were paired. Results suggested that advantages in resource exploitation and energy acquisition were enjoyed by pairs.

Analysis of esophageal and gizzard contents indicated that vegetation comprised 95.3, animal matter 4.2, and seeds 0.5% of the diet. Algae, Eleocharis parvula, Ruppia maritime, and Myriophyllum spicatum were primary foods consumed and utilization varied seasonally. Food habits did not differ by sex but did by habitat. Diets were selected based upon quality, quantity and preference of available vegetation.

Except for changes in body weight, lipid level, gut morphology, and plumage, little morphological variation occurred in wintering gad- wall. Adults completed alternate molt prior to immatures, correlating with their earlier initiation of courtship activities. Weights and lipid levels increased rapidly in fall, declined in midwinter, and increased slightly in spring in adults. Data on fall weights of immatures indicated no change or a decline with time. Gut morphology varied in response to diet quality and most measurements increased significantly during the study.

These data reflect the importance of energy acquisition to gad- wall, reliance upon vegetation, and adaptib'lity to various habitats and diets. Management must insure that habitat providing abundant, preferred vegetation is available to wintering gadwall.

Download

Share

COinS