Multi-scale habitat selection affects offspring survival in a precocial species / P.M. Bloom, R.G. Clark, D.W. Howerter, and L.M. Armstrong.

Includes bibliographical references (pages 1257-1259).

In theory, habitat preferences should be adaptive.
Accordingly, fitness is often assumed to be greater in
preferred habitats; however, this assumption is rarely
tested and, when it is, the results are often equivocal.
Habitat preferences may not directly convey fitness
advantages if animals are constrained by tradeoffs with
other selective pressures like predation or food availability.
We address unresolved questions about the survival
consequences of habitat choices made during brood-rearing
in a precocial species with exclusive maternal care
(mallard Anas platyrhynchos, n = 582 radio-marked
females on 27 sites over 8 years). We directly linked
duckling survival with habitat selection patterns at two
spatial scales using logistic regression and model selection
techniques. At the landscape scale (55–80 km2), females
that demonstrated stronger selection of areas with more
cover type 4 wetlands and greater total cover type 3
wetland area (wetlands with large expanses of open water
surrounded by either a narrow or wide peripheral band of
vegetation, respectively) had lower duckling survival rates
than did females that demonstrated weaker selection of
these habitats. At finer scales (0.32–7.16 km2), females
selected brood-rearing areas with a greater proportion of
wetland habitat with no consequences for duckling survival.
However, females that avoided woody perennial
habitats composed of trees and shrubs fledged more
ducklings. The relationship between habitat selection and
survival depended on both spatial scale and habitats
considered. Females did not consistently select broodrearing
habitats that conferred the greatest benefits, an
unexpected finding, although one that has also been
reported in other recent studies of breeding birds.