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Mallard duckling growth and survival in relation to aquatic invertebrates

Journal of Wildlife Management

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Abstract

Identification and assessment of the relative importance of factors affecting duckling growth and survival are essential for effective management of mallards on breeding areas. For each of 3 years (1993-95), we placed F1-generation wild mallard (Anas platyrhynchos) females on experimental wetlands and allowed them to mate, nest, and rear broods for 17 days. We manipulated invertebrate densities by introducing fathead minnows (Pimephales promelas) at high densities in half of the wetlands on which broods were confined. Day-17 body mass of surviving ducklings (n = 183) was greater for ducklings that were heavier at hatch; the difference averaged 1.7 g at day 17 for each 1.0 g at hatch (P = 0.047). Growth ratio (the proportion of body mass attained by ducklings when they were last measured relative to that predicted for wild female mallard ducklings) also was positively related to body mass at hatch (P = 0.004). Mean day-17 body mass and mean growth ratio of ducklings per brood (each adjusted for body mass at hatch) were positively related to numbers of aquatic invertebrates (Ps < 0.001) and negatively related to variance in the daily minimum air temperature during the exposure period (Ps < 0.020). Early growth of mallards was more sensitive to variation in numbers of invertebrates than to air temperature or biomass of invertebrates. Duckling survival was positively related to growth ratio (P < 0.001). Our study provides parameter estimates that are essential for modeling growth and survival of mallard ducklings. We emphasize the need for conserving brood-rearing wetlands in the Prairie Pothole Region that are capable of supporting high densities of aquatic invertebrates.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Mallard duckling growth and survival in relation to aquatic invertebrates
Series title:
Journal of Wildlife Management
Volume
62
Issue:
1
Year Published:
1998
Language:
English
Description:
p. 124-133
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
124
Last page:
133
Number of Pages:
9