PREDATOR IDENTIFICATION AT SIMULATED WATERFOWL NESTS USING INCONSPICUOUS HAIR CATCHERS AND WAX-FILLED EGGS

We tested the efficiency of thin, inconspicuous wire hair catchers and wax-filled eggs to differentiate between mammalian and avian predator s of upland nesting ducks. In contrast to a previously tested hair cat cher (lacerated metal sheeting, modified bridge-stake design), our hai r catcher was designed to be unobtrusive, to avoid attracting predator s to nests. In total, 578 simulated nests (78 with metal sheeting and 500 with inconspicuous wire hair catchers) were set up in Thickwood Hi lls, Saskatchewan. Each nest contained seven fresh chicken eggs and tw o wax-filled eggs for collecting tooth and beak marks of predators. Pr edation by mammals and birds accounted for 30 and 70% of depredated ne sts (n = 78) with metal-sheeting hair catchers compared with 76.5 and 23.5% (n = 143) of nests with inconspicuous wire hair catchers, respec tively; 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 depreda ted nests contained marked wax-filled eggs, of which 75% related to ma mmalian predation and 25% to avian predation. Overall, we could differ entiate between mammalian and avian predation in 77.6% of destroyed ne sts. Based on hair samples, the striped skunk (Mephitis mephitis) was the dominant predator (75% occurrence) among mammalian species.