Waterfowl Nesting in Fall‐Seeded and Spring‐Seeded Cropland in Saskatchewan

Abstract

Waterfowl nesting in annual croplands has remained a little‐known aspect of waterfowl nesting ecology because of the inability of many studies to systematically search this habitat through the nesting season. Where searches have been conducted, they are generally restricted to the period prior to seeding, and many nests found are destroyed by the seeding operation. Consequently, fall‐seeded crops have been promoted as an alternative cropping practice that could increase nest survival of waterfowl nesting in croplands. During 1996–1999, we conducted 3–4 complete nest searches on 4,274 ha of cropland, including spring‐seeded wheat and barley, winter wheat, and fall rye in southern Saskatchewan, Canada. Using suites of predictive models, we tested hypotheses regarding relative nest abundance and nest survival among crop types and tested the influence of several landscape‐scale covariates on these metrics. Apparent nest densities were higher in fall‐seeded crops (winter wheat: 0.39 nests/ha, fall rye: 0.25 nests/ha) than in spring‐seeded crops (0.03 nests/ha), and nest density in spring‐seeded croplands increased with percent cropland and percent wetland habitat in the surrounding landscape. Nest survival was higher in winter wheat (38%) than in either fall rye (18%) or spring‐seeded crops (12%), and nest survival in spring‐seeded crops increased with relative nest initiation date. Nest survival was unaffected by surrounding landscape characteristics but tended to be higher in years of average wetness. Based on our findings, winter wheat and fall rye have the potential to provide productive nesting habitat for ≥7 species of upland nesting ducks and fall‐seeded crops are a conservation tool well suited to highly cropped landscapes.

Agricultural destruction of Northern Pintail nests on cropland in prairie Canada

“…Nest survival of ducks in spring-seeded cropland is low compared to most other habitat types (Klett et al 1988, Greenwood et al 1995), ranging from < 1-4% (Richkus 2002), 2% (Greenwood et al 1995), and 7% (Klett et al 1988). Devries et al (2008a) reported a relatively high nest success rate of 12% in spring-seeded cropland and opined that this may have been a result of their inclusion of late-season nests because success rates in spring-seeded cropland can increase substantially throughout the growing season (Emery et al 2005). Recently, one of us (JHD) modeled mean pintail nest success in spring-seeded cropland to be 5.1% (i.e., daily survival rate = 0.9111 + 0.0146; Table 2) based on the fate of 153 nests in cropland (Devries et al 2018).…”

“…More contemporary studies from prairie Canada have found that predation is the predominant cause of duck nest loss in cropland rather than farming operations. Greenwood et al (1995) and Devries et al (2008a) reported that 17% and 22%, respectively, of nests of various duck species in cropland (primarily spring-seeded) in prairie Canada were lost to agricultural activity. Pintail nest loss from agricultural practices in spring-seeded cropland estimated from various sources averages 21.8% (+ 1.3%; Table 2).…”

“…Pintails are unique in that (i) they are the only prairie duck species that has exhibited a long-term decline and failed to respond positively to high pond numbers over the past decade, and (ii) they have a large proportion of their population nesting in cropland where nest success is lower than most other habitat types. The fact that duck nest success is relatively high, e.g., > 20%, in fall-seeded crops (Cowan 1982, Duebbert and Kantrud 1987, Devries et al 2008a, Skone et al 2015 and higher than in most other habitat types (Klett et al 1988, Greenwood et al 1995, suggests that in the absence of spring tillage, nest success on seeded cropland can be quite high. Although the high nest success in fallseeded cropland is confounded by its taller vegetative cover earlier in the summer compared to spring-seeded crops, the evidence is suggestive that the loss from agricultural activities may indeed be additive and responsible for the decline in the pintail population.…”

“…Early estimates of nest destruction in cropland indicated that agricultural activity caused 34-56% of the nest losses (Milonksi 1958, Higgins 1977. Although Miller and Duncan (1999) considered loss to agricultural activities to be an important source of pintail nest destruction in cropland, a number of more recent studies have suggested that predation is the predominant cause of duck nest loss in cropland (Richkus 2002, Devries et al 2008a, Devries 2014, Skone et al 2015, Devries et al 2018. Although a number of studies have documented the habitat nesting preferences of pintails (Klett et al 1988, Greenwood et al 1995, Devries et al 2018, we are unaware of any estimate of numbers of nests initiated in cropland and impacted by incidental take from agriculture.…”

Northern Pintail (Anas acuta) survival, recovery, and harvest rates derived from 55 years of banding in Prairie Canada, 1960&#8211;2014

“…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. However, there are indications that widespread use of fall-seeded crops in Prairie Canada could improve nest success and the abundance of pintails (Devries et al 2008, Skone et al 2016). …”