According to theory, habitat selection by organisms should reflect the associated probability of survival or reproductive success. Understanding habitat selection, at multiple scales, is of interest not only from a theoretical perspective, but from an applied perspective for species conservation. Northern pintails (Anas acuta) are migratory, temperate-nesting birds that breed in greatest concentrations in the prairies of North America. Declining populations suggest that habitat loss and changing land use may have decoupled formerly reliable fitness cues from selection of suitable nest habitat.
I used data from 62 waterfowl nesting study sites in prairie Canada (1997–2009), to examine whether nest survival, a primary fitness metric, at nest and habitat patch scales, was predictive of habitat selection at corresponding scales. In addition, I used systematic long-term annual pintail population monitoring data (1961–2009), and recruitment indices (juvenile:adult female ratio) from hunter harvest, to examine adaptive habitat selection among landscapes within the Prairie Pothole Region (PPR). The influences of breeding population density and landscape composition were examined at all scales.
At nest and patch scales, pintail nest survival varied with nest initiation date, nest habitat, pair density, and landscape composition. Nest habitat preference reflected patterns in nest survival suggesting nest habitat preference is adaptive. Preference was generally low for habitats with low nest survival (e.g., spring-seeded cropland) and high for habitats with high nest survival (e.g., idle grassland). Differences in preference among habitats weakened at high breeding density and in landscapes with more grassland.
Population-level recruitment tended to be greater when pintails settled in landscapes that were wetter than normal, contained more grassland, and were moderately variable in local elevation. Pintails were strongly associated with wetter than normal landscapes but shifted into cropland-dominated landscapes and flatter landscapes when populations were high. My results indicated that pintails express adaptive habitat associations with density-dependence acting through buffer mechanisms.
Finally, I use the results of the above analyses to, 1) model and map the estimated long-term average spatial abundance of pintail pairs across the PPR as a function of landscape-level covariates, and 2) construct a deterministic model predicting pintail productivity given habitat and landscape attributes. These models allow conservation efforts to be targeted to affect the most birds, and they allow estimation of the demographic response to conservation actions.
| Identifer | oai:union.ndltd.org:USASK/oai:ecommons.usask.ca:10388/ETD-2014-10-1788 |
| Date | 2014 October 1900 |
| Contributors | Clark, Robert G. |
| Source Sets | University of Saskatchewan Library |
| Language | English |
| Detected Language | English |
| Type | text, thesis |
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