Midwest Fish & Wildlife Conference 2018

AUTHORS. Kyle O. Daly, U.S. Fish & Wildlife Service; David E. Andersen, Minnesota Cooperative Fish & Wildlife Research Unit; Wayne L. Brininger, U.S. Fish & Wildlife Service; Thomas R. Cooper, U.S. Fish & Wildlife Service

ABSTRACT. We estimated full-season productivity (i.e., juveniles raised to independence from adult care) of American woodcock (Scolopax minor; hereafter, woodcock) directly using radio telemetry, and indirectly by capturing woodcock using mist nets and night lighting. Indirect methods used to estimate woodcock full-season productivity are more cost- and effort- efficient than direct measures and may provide comparable estimates. I 2011 and 2012, we radio-marked and tracked 41 adult female and 73 juvenile woodcock, and monitored 51 broods and 48 nests at a habitat-management demonstration area in Minnesota. We used the Kaplan-Meier with staggered entry method to estimate survival rates of females, nests, and juveniles, and from these survival rate estimates developed a population model to derive estimates of full-season productivity. In July of 2011 and 2012, we used mist nets to capture 204 woodcock during crepuscular movements from diurnal feeding cover to roosting fields and 69 woodcock via night-lighting on roosting fields. Our full-season productivity estimates (juveniles/adult females) derived from our population model were 1.24 (95% CI: 0.39 – 2.56) in 2011 and 2.87 (95% CI: 1.60 – 4.85) in 2012. We attribute the higher full-season productivity estimate in 2012 to higher nest and juvenile survival rates. Full-season productivity estimates from mist-netting were 3.82 (95% CI: 1.99 – 7.13) in 2011 and 2.37 (95% CI: 1.43 – 3.73) in 2012. Full-season productivity estimates for night lighting were 1.62 (95% CI: 0.69 – 3.28) in 2011 and 0.42 (95% CI: 0.06 – 1.00) in 2012. Estimates from indirect methods varied considerably between years, with neither method providing full-season productivity estimates comparable to those derived from our population model. Based on these results, we suggest that direct estimates of full-season productivity, although more labor-intensive and costly are probably necessary to effectively assess full-season productivity.