Evaluating occurrence and abundance of displaying male American woodcock (Scolopax minor) north of the current Singing-Ground Survey range

Abstract

Displaying male American woodcock (Scolopax minor) are monitored by the American Woodcock Singing-Ground Survey (SGS), whose findings guide woodcock research and management decisions. However, the SGS may not cover all available woodcock breeding range, particularly in more northern regions. Though there have been frequent recommendations to expand the SGS farther north, occurrence and abundance of woodcock north of the SGS have never been evaluated. To address this issue, we used SGS data collected in Canada between 2000 and 2019 to 1) identify the spatial scale at which landscape covariates had the strongest effect (i.e., scale of effect) and 2) evaluate the effect size of 16 landscape covariates on male woodcock occurrence and abundance index, and 3) develop a predictive map to identify priority areas for SGS expansion in Canada. We found that landscape covariates had the strongest effect on occurrence and the abundance index at a 310-m radius, suggesting that the most important influence on male woodcock habitat selection and habitat use was the presence of display habitat. Our results also support previous studies showing male woodcock preference for moist areas with young, broadleaf forest intermixed with pasture and grassland clearings for their display. Additionally, we identified sites throughout eastern Canada likely to support relatively high abundances of displaying males during the breeding season. Many of these sites were north and west of the current SGS range, and we identified road-accessible locations for possible SGS expansion in Manitoba, Ontario, Québec, and Newfoundland. Expanding survey route coverage into areas of predicted woodcock occurrence could improve woodcock population monitoring and guide more effective management and conservation decisions.