Survival and Cause-Specific Mortality of Female Northern Pintails in Southern Saskatchewan

Abstract

Unlike most prairie-nesting ducks, the North American population of northern pintails (Anas acuta) has shown limited response to improved wetland conditions on the U.S. and Canadian prairies during the mid to late 1990s. Because adult female survival is a key parameter affecting waterfowl population dynamics, and a large fraction of annual mortality for some dabbling ducks occurs during the nesting season, we used radiotelemetry to estimate nesting season survival and cause-specific mortality of adult female northern pintails that were monitored during an induced renesting study. We conducted our research in a predominantly agricultural landscape in southern Saskatchewan during 1998-2000, an area that is typical of much of the pintail's prairie breeding range. The survival rate of 140 females for a 75-day interval (30 Apr-14 Jul) during the nesting season was 0.806 ± 0.046. Survival did not vary among years or between ages (second-year, after second-year), nor was it related to female body condition (body mass adjusted for structural size, date, and year of capture). We documented 15 mortalities and found that the 75-day mortality rate due to raptors (0.141 ± 0.040) was greater than that due to red fox (Vulpes vulpes; 0.011 ± 0.011), collisions with power lines (0.011 ± 0.011), or unknown factors (0.039 ± 0.027). Our results differ from prior research that indicated red fox was a major predator of female pintails during the nesting season. Raptors were the primary mortality agent for female pintails, perhaps because of limited exposure during incubation in our study, or the use of open habitats by pintails in southern Saskatchewan. Management programs that provide nesting or wetland habitats with overhead concealment, or that reduce perch sites for raptors in areas with high pintail densities, may decrease the risk of avian predation on female pintails. JOURNAL OF WILDLIFE MANAGEMENT 69(2):574-581; 2005

Northern Pintail (Anas acuta) survival, recovery, and harvest rates derived from 55 years of banding in Prairie Canada, 1960–2014

“…Summerfallow, the practice of leaving land uncropped for a growing season, declined dramatically in Prairie Canada in the last quarter of the 20th century, when there was a shift to continuous annual cropping (Carlyle 1997). Pintails nest relatively early and do not avoid nesting in uplands with sparse cover, e.g., crop stubble from the previous year, to the same degree that other prairie nesting dabbling ducks do (Greenwood et al 1995, Podruzny et al 2002, Richkus et al 2005. Therefore, pintails and their nests may be more vulnerable to spring seeding activities than other species of prairie ducks, leading to reduced nest success and overall productivity (Hestbeck 1995, Miller and Duncan 1999, Podruzny et al 2002, Hebert and Wassenaar 2005.…”

“…1). Survival, migration, and productivity are all important factors that determine population abundance, but adult survival can have the largest influence on population dynamics (Johnson et al 1992, Flint et al 1998, Richkus et al 2005. Most of the land base in southern Alberta and Saskatchewan is dominated by agriculture in the form of crops or pasture, and natural areas are composed mainly of grasses, woods, and wetlands.…”

“…Unique changes in agricultural practices or climate in Prairie Canada may have had a disproportionately negative effect on the survival of pintails breeding in that region (Bethke and Nudds 1995). Predators can affect not only nest success but also adult survival, especially for nesting females (Richkus et al 2005). It is possible that changes in predator assemblages that have occurred in Prairie Canada have led to declines in survival.…”

The effects of a large‐scale wind farm on breeding season survival of female mallards and blue‐winged teal in the Prairie Pothole Region

“…Several investigations have reported that survival of female ducks during the breeding season is lowest when females are nesting and are vulnerable to predators (Devries et al , Richkus et al , Arnold et al ). Consistent with these findings, survival of female mallards at TWF and REF was lowest when a high proportion of radio‐marked females were incubating nests (Fig.…”

“…Changes in local predator community composition or predator abundance may also explain differences in survival between TWF and REF. Raptors are responsible for considerable female mortality in the PPR (Sargeant et al , Richkus et al ). Disturbance at wind‐developed landscapes may increase the abundance of raptor prey species (Morrison and Davis , Thelander et al ) and because TWF began operation in 2008, this may have been a mechanism of temporal differences in raptor abundances at TWF as well.…”