Factors associated with Autumn rearing of duck broods in temperate North America

Wildfowl
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Abstract

Dabbling ducks Genus Anas occasionally nest during mid- and late summer in the Prairie Pothole Region (PPR) of midcontinent North America but little information is available on their Autumn-reared broods or those of other duck genera. Densities, species composition, and wetland habitat use by Autumn reared duck broods (age classes I and II) were determined on randomly distributed transects on a 3,735 km^2 study area in eastern North Dakota. Brood densities (SE) averaged 0.380.08, 0.300.08 and 0.230.10 broods km^-2 during 1993-95 with dabbling ducks accounting for 70, 44, and 9%, and diving ducks 30, 54, and 91% of sighted broods. The principal species were Blue-winged Teal Anas discors, 21%; Gadwall A. strepera, 11%; Mallard A. platyrhynchos, 7%; Redhead Aythya americana, 13%, and Ruddy Duck Oxyura jamaicensis, 35%. Of Blue-winged Teal and Mallard broods, 67% of each were located on seasonal ponds, and 50, 56, and 59% of Gadwall, Redhead and Ruddy Duck broods were on semi-permanent ponds. Interspecific variation in numbers of Autumn-reared broods resulted, in part, from intrinsic differences among species in capacity to nest during mid- and late summer. Survival of thousands of class I and II dabbling duck broods to mid-September during 1993-94 probably resulted from a combination of factors including an abundance of seasonal ponds, low rainfall, and limited cold weather through mid-September when brood surveys were conducted. Redheads and Ruddy Ducks do not terminate breeding under long daylengths in late spring so summer nesting accounts for a much larger portion of the annual nesting effort than in dabbling ducks except under drought conditions when ducks generally terminate reproduction by midspring.

Publication type Article
Publication Subtype Journal Article
Title Factors associated with Autumn rearing of duck broods in temperate North America
Series title Wildfowl
Volume 52
Year Published 2001
Language English
Publisher Wildfowl & Wetlands Trust
Contributing office(s) Northern Prairie Wildlife Research Center
Description 14 p.
First page 145
Last page 158
Other Geospatial North America
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