Assessment of techniques to evaluate American woodcock population response to best management practices applied at the demonstration-area scale

Abstract

American woodcock (<italic>Scolopax minot</italic>; hereafter, woodcock) have experienced long-term population declines across their breeding range based on the American woodcock Singing-ground Survey. Wing-collection surveys have also indicated a decline in woodcock recruitment across their range, especially in the Central Management Region. These declines have been widely attributed to loss or alteration of young forest cover types that support woodcock reproduction across their breeding range. In response to these apparent declines in woodcock abundance and recruitment, a system of woodcock habitat demonstration areas is being developed throughout the woodcock breeding range where specific Best Management Practices (BMPs) are applied with the goal to stabilize and ultimately increase populations. Application of BMPs at a demonstration-area scale (~200-800 ha) is designed to positively influence woodcock population growth by improving habitat quality and abundance at a landscape scale. However, how woodcock vital rates are influenced by BMPs applied at a landscape scale is not fully understood, and techniques used to evaluate woodcock populations at the demonstration-area scale have not been assessed. The objectives of our research were to (1) estimate survival of adult females, nests, and juveniles using radio telemetry and assess relationships between survival and vegetation structure resulting from BMPs, life history traits, and weather, (2) directly estimate a measure of woodcock recruitment (juveniles/adult female during late summer) at a landscape scale by using survival estimates in a population model, and use direct estimates of recruitment to evaluate the accuracy and usefulness of indirect estimates of recruitment based on less costly and effort-intensive methods (specifically mist netting and night lighting on summer roosting fields), and (3) test for effects of radio transmitters on juvenile woodcock survival. In 2011 and 2012, we radio-marked and tracked 41 adult female and 73 juvenile woodcock, and monitored 51 broods and 48 nests. Breeding season cumulative survival for adult females was consistent between years, whereas nest and juvenile survival were related to year. Juvenile survival was also positively related to age, minimum temperature, and stem density, and negatively related to precipitation. We found no effects of radio-marking juvenile woodcock. In July of 2011 and 2012, we captured 204 woodcock using mist nets during crepuscular movements from diurnal feeding cover to roosting fields and 69 woodcock via night-lighting on roosting fields. Our recruitment estimates (juveniles/adult female) derived from our demographic model were higher in 2012 than 2011 due to higher nest and juvenile survival rates during that year, suggesting that nest and juvenile survival, and factors related to nest and juvenile survival, may be key to understanding woodcock population ecology. Our assessment of indirect methods to estimate woodcock recruitment at a landscape scale indicated that the indirect methods we considered of estimating woodcock recruitment at a landscape scale are likely not reliable proxies for estimating recruitment directly.