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Document Type

Research

Keywords

Northwestern Iowa, Branta canadensis maxima, productivity, nesting success, gosling survival

Abstract

Productivity, gosling habitat use, and survival of giant Canada geese (Branta canadensis maxima) in northwestern Iowa were studied in 1977 and 1978. Arrival of geese on the breeding grounds in March coincided with the first open water in smaller wetlands. Initial laying dates (25 March 1977 and 26 March 1978) were probably influenced by photoperiod, timing of arrival at the breeding grounds, and ice conditions. The density of successful nests in 1978 averaged.12 nests/ha of wetland. Nest density was highest in cover class 2 wetlands. The large mean clutch size of 6.0 eggs for 185 nests suggested that most of the breeding population was fairly old. Most nests hatched 10-20 May. Of all the 211 nests found during the study, 166 (79%) hatched. Nesting success was greater (P < 0.01) in artificial nest structures than in natural nest sites. Desertion was the main cause of nest failure. Of 1126 eggs laid in 205 nests, 862 (77%) hatched. Hatching success of 1,002 eggs in 167 clutches incubated full term was 86%. Fewer geese renested in 1977 than in 1978, possibly because reduced water levels in 1977 made nest sites unattractive. The mean initial brood size for 165 nests was 5.3. Mudflats, pasture-like uplands, and artificial islands were used by goslings for foraging, loafing, and roosting. Gosling survival was 73-90+ %; inclement weather was the major mortality factor.

Publication Date

June 1980

Journal Title

Proceedings of the Iowa Academy of Science

Volume

87

Issue

2

First Page

56

Last Page

61

Copyright

© Copyright 1980 by the Iowa Academy of Science, Inc.

Language

EN

File Format

application/pdf

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