Abstract
Waterfowl rely on breeding habitat availability for successful reproduction. Breeding habitat availability likely changes throughout the season and among years as weather patterns change and thus productivity rates are likely susceptible to these changes. We used data from 1961 to 2011 to investigate effects of weather, breeding habitat availability and abundance of breeding mallards (Anas platyrhynchos) on productivity rates of mallards breeding in the Great Lake states (Michigan, Minnesota, and Wisconsin; hereafter GLS). We hypothesized that productivity rates would increase with wetter and warmer conditions however, extreme temperatures may have a negative impact and that high breeding density may negatively impact productivity rates. Specifically, we looked at the effects of average June and July temperature and precipitation, the Palmer Hydrological Drought Index (hereafter PHDI), and wetland counts to model productivity rates across the three states for the time series. We used a reduced time series model set to evaluate the impacts of wetland counts on productivity. We found that in general, wetter conditions, as indexed by high positive PHDI values and relationships with pond abundance, positively affected productivity. We believe that breeding habitat availability is likely a reasonable predictor of mallard productivity rates in the GLS.
Highlights
Changing climatic patterns, such as increased drought (Johnson et al 2005) from hotter and drier conditions, are likely to negatively impact wetland conditions, such as permanency and productivity (Peterson et al 1997; McCarty 2001; Hoegh-Guldberg and Bruno 2010)
Beta terms from the top model suggest that Minnesota productivity rates are different than those of Wisconsin (Fig. 3); WI has greater productivity but effects of weather and PHDI are similar across states
Our results suggest that annual variation in GLS mallard productivity rates was most influenced by wetland hydrologic conditions, as indexed by both the PHDI and POND variables, more so than temperature, precipitation, and overall mallard abundance during the breeding season
Summary
Changing climatic patterns, such as increased drought (Johnson et al 2005) from hotter and drier conditions, are likely to negatively impact wetland conditions, such as permanency and productivity (Peterson et al 1997; McCarty 2001; Hoegh-Guldberg and Bruno 2010). We estimated annual productivity rates of mallards breeding in the GLS to understand how productivity changed over the period 1961–2011 and was affected by wetland habitat conditions (i.e., via variation in regional hydrology), weather, and mallard abundance during the breeding season. S. Fish and Wildlife Service 2014); since POND was not available across the 51-year study and both MN and WI do not survey the entire state, we assessed a second model set using a 3-month average (April–June) PHDI to index breeding habitat conditions during peak settling and nesting (Bellrose 1976). We assessed model fit by fitting a linear regression model to the actual and predicted responses on the test data sets from the best fitting model and examined r2
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