Temporal variability in the way local habitat affects duck population growth / Richard E. Feldman, Michael G. Anderson, David W. Howerter, and Dennis L. Murray.

Includes bibliographical references (pages 532-533).

Climate change is expected to lead to greater
temporal climatic variability across broad spatial extents. A
potential consequence is that shifts in climatic conditions
might alter how local habitat affects the population growth
of animals dependent on those habitats for at least part of
their life cycle. We tested whether such a phenomenon
occurred when the North American Prairie Pothole Region
transitioned through periods of wet and dry conditions by
modeling the population growth of seven duck species over
52 years (1961–2012). We found that the influence of local
habitat quality—indexed by wetland availability—on duck
population growth varied in magnitude and direction on an
annual basis. While the effect of wetlands was relatively
small in most years, there were some years in which wetlands
strongly affected duck population growth in both
positive and negative directions (e.g., negative in 2002 and
positive in 2008). Contrary to our expectation, inter-annual
variability in the effect of wetlands on duck population
growth did not depend on regional precipitation. We also
found that for two species—American Wigeon (Anas
americana) and Green-winged Teal (A. carolinensis)—
duck population growth in the presence of wetlands rarely
differed from what would be expected solely under density
dependence. Our study is the first to demonstrate that the
effect of local habitat on population growth varies over
time even if the cause of that variation remains unexplained.
Consequently, any study that attempts to identify a
species’ critical habitat using time series abundance data
must consider that local relationships are non-stationary.
More complicated measures of climate change may reveal
how local drivers of population growth depend on broader
temporal climatic patterns.