Doctor of Philosophy (PhD)
Forestry, Wildlife, and Fisheries
Unlike most prairie nesting ducks (Anas spp.), the North American population of northern pintails (A. acuta, hereafter pintails) has failed to respond as expected to improved wetland conditions on the U.S. and Canadian prairies during the mid to late 1990s. My primary objectives were to test the “ecological trap hypothesis” on a landscape level by examining pintail nest site selection and nest success in a highly agricultural environment in southern Saskatchewan. I also used radiotelemetry to estimate renesting and breeding season survival rates of female pintails; two parameters that are important in productivity and life cycle models. Most (51%) pintail nests were found in crop stubble and generally pintails nested in habitats in proportion to their availability on the landscape. In contrast, most (82%) mallard nests were located in edge and grassland habitats. Mallards nested in habitats with dense cover in greater proportion to their availability and avoided crop stubble. Nest success estimates in crop stubble were lower (<1-4% vs. 6-37%) than the surrounding habitats with greater cover. Nest success estimates in crop stubble were abysmal largely due to high rates of nest predation. Only 20-33% of nests in crop stubble failed due to spring cultivation. For 1998, 1999, and 2000, overall renesting rates for females trapped throughout the nesting season were 50%, 71%, and 41%, but were 61%, 90% and 62% when only first nesting females were included. Renesting propensity declined seasonally, but at different rates among years likely due to variation in wetland abundance. Most (58%) females renested, but few (37%) initiated multiple renests. Survival rate for my 75-day interval (April 30 – 14 July) was 0.81 ± 0.05. Cause-specific mortality rates were greater for avian predators (0.14 ± 0.04) than other sources of mortality. The pintail’s high propensity to nest in crop stubble where nest success is low coupled with lower renesting and breeding season survival rates than mallards may partially explain their meager response to improved wetland conditions. Management programs to facilitate pintail recovery should be targeted at increasing nest success by providing safe nesting habitat.
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Release the entire work immediately for access worldwide.
Richkus, Kenneth Daniel, "Northern pintail nest site selection, nest success, renesting ecology and survival in the intensively farmed prairies of southern Saskatchewan: an evaluation of the ecological trap hypothesis" (2002). LSU Doctoral Dissertations. 475.
Frank C. Rohwer