Predator identification at simulated waterfowl nests using inconspicuous hair catchers and wax-filled eggs

Abstract

We tested the efficiency of thin, inconspicuous wire hair catchers and wax-filled eggs to differentiate between mammalian and avian predators of upland nesting ducks. In contrast to a previously tested hair catcher (lacerated metal sheeting, modified bridge-stake design), our hair catcher was designed to be unobtrusive, to avoid attracting predators to nests. In total, 578 simulated nests (78 with metal sheeting and 500 with inconspicuous wire hair catchers) were set up in Thickwood Hills, Saskatchewan. Each nest contained seven fresh chicken eggs and two wax-filled eggs for collecting tooth and beak marks of predators. Predation by mammals and birds accounted for 30 and 70% of depredated nests (n = 78) with metal-sheeting hair catchers compared with 76.5 and 23.5% (n = 143) of nests with inconspicuous wire hair catchers, respectively; metal-sheeting hair catchers created a severe bias toward bird predation. Restricting our analysis to nests with inconspicuous wire hair catchers, hair and feather samples were obtained at 45.1 and 2.2% of depredated nests (n = 317), respectively. Another 30.3% of depredated nests contained marked wax-filled eggs, of which 75 % related to mammalian predation and 25% to avian predation. Overall, we could differentiate between mammalian and avian predation in 77.6% of destroyed nests. Based on hair samples, the striped skunk (Mephitis mephitis) was the dominant predator (75 % occurrence) among mammalian species.Resume : Nous avons CprouvC 17efficacitC de capteurs de poils faits de fil de mCtal fin et peu visible ainsi que d'oeufs remplis de cire dans des expkriences destinkes a reconnaltre les oiseaux prkdateurs et les mammifires prkdateurs de nids de canards de terres hautes. Contrairement aux capteurs de poils utilisCs prCcCdemment (feuilles de mCtal lacerCes), notre appareil peu visible a Ct C c o n y pour Ctre peu encombrant et peu enclin a attirer les prCdateurs aux nids. Au total 578 nids simulCs (78 avec feuilles de metal lacCrCes et 500 avec capteurs faits de fil fin) ont Ct C installCs a Thickwood Hills, Saskatchewan. Chaque nid contenait sept oeufs de poule frais et deux oeufs remplis de cire destinCs a enregistrer les marques de dents et de becs des prkdateurs. Dans les nids munis de feuilles de metal, 30% de la prCdation Ctait attribuable aux mammifires et 70% aux oiseaux (n = 78), alors que dans les nids a capteurs de fil fin, 76,5% de la prCdation Ctait attribuable aux mammifkres et 23,5% aux oiseaux (n = 143); les feuilles de metal ont donc pour effet de favoriser la prCdation par les oiseaux au dCtriment de celle exercCe par les mammifires. Ne tenant compte que des nids a capteurs de poils en fil fin dans nos analyses, des poils ont Ct C recueillis dans 45,1% des nids attaquCs, et des plumes, dans 2,2% des nids pillCs (n = 317). De plus, dans 30,3% des nids pillCs, les oeufs remplis de cire comportaient des marques, dont 75% faites par des mammifkes et 25% par des oiseaux. Dans l'ensemble, il a Ct C possible de diffkrencier les prkdateurs mammifires et les prCdateurs ...

Adaptive nest clustering and density‐dependent nest survival in dabbling ducks

“…However, large numbers of North American waterfowl breed on the prairies of the Dakotas and south–central Canada, where the predator community is quite different (Klett et al 1988, Greenwood et al 1995). In those regions, red foxes Vulpes vulpes are important nest predators and they specifically target duck nests, posing a risk to both eggs in the nest and the incubating female (Klett et al 1988, Johnson et al 1989, Pasitschniak‐Arts and Messier 1995). After depredating a nest, foxes are likely to employ area‐restricted searching to locate additional nests (Seymour et al 2003, 2004), because foxes do not become “satiated” after depredating a single nest.…”

Of mice and mallards: positive indirect effects of coexisting prey on waterfowl nest success

“…Predators are the primary cause of duck nest failure and significantly limit recruitment (Sargeant and Raveling 1992), potentially below replacement levels for mallards (Cowardin et al 1985) and other duck species (Greenwood et al 1987, Klett et al 1988). The striped skunk is a predominant predator of duck nests in various habitats throughout its range (Greenwood 1986, Crabtree et al 1989, Johnson et al 1989, Pasitschniak‐Arts and Messier 1995, Larivière and Messier 1998), despite preying extensively on other food resources (Verts 1967, Greenwood et al 1999). McLandress et al (1996) implicated striped skunks as a major predator of duck nests in the Suisun Marsh.…”

Is predation on waterfowl nests density dependent? – Tests at three spatial scales

“…Within each field (hereafter called replicates), three 1‐ha treatment plots were arranged systematically along the length of the replicate. We randomly selected one end of the replicate then positioned the first treatment plot 50 m from the replicate's end and >40 m from either side of the replicate to reduce any potential edge effects (Pasitschniak‐Arts and Messier 1995). The second and third treatment plots also were positioned >40 m from either side of the replicate, and each treatment plot was separated by 200 m.…”