Surveys and Habitat Use of the Whimbrel (Numenius phaeopus) During Fall Migration Along the Acadian Peninsula of New Brunswick, Canada, 2014
Abstract
The whimbrel (Numenius phaeopus) is a large, highly migratory shorebird that breeds in arctic and sub-arctic latitudes and winters in the tropics. The North American race (N.p. hudsonicus) includes three disjunct breeding populations, all of which winter primarily in Central and South America. The two rufiventris populations breed in Alaska and the Northwest Territories of Canada (Engelmoer and Roselaar 1998). These western whimbrels primarily use different migration routes and wintering grounds and are most likely genetically segregated populations (CCB/CWS unpublished tracking data). The hudsonicus population breeds in the Hudson Bay Lowlands along the James and Hudson Bays (Jehl and Smith 1970, Skeel and Mallory 1996). The populations of whimbrels utilizing the Atlantic Coast and northeast South America have declined by up to 50% in recent decades (Watts and Truitt 2011, and RIG Morrison et al., unpublished data, from Andres et al. 2012) and both the hudsonicus and Northwest Territories rufiventris populations are of conservation concern (Morrison 2006, Bart et al. 2007, Watts and Truitt 2011). In an effort to better understand the population size and habitat use of whimbrels utilizing the Acadian peninsula during fall migration, we designed aerial and ground based surveys to accomplish this goal. We detected 339 whimbrels during the first aerial survey and 615 during the second survey. Whimbrels were distributed along the peninsula from Brantville to Miscou Island, though concentrations of whimbrels were higher near Miscou Island. Of the 954 whimbrels detected on aerial surveys, 908 (95%) were observed in harvest stage fields, 5 (<1%) in development stage fields, 7 (<1%) flushed from unknown stage fields, and 34 (3.5%) from coastal beaches or barrier islands. We surveyed 103 ground transects twice each during the field season. We surveyed a total length of 58.5 km of transects within the five geographic areas (Brantville, Lord and Foy, Val-Doucet, Tracadie-Sheila, and Pigeon Hill/Lameque Island). We surveyed approximately 1,448 hectares of blueberry fields, with 773ha in active blueberry production, 653ha in growth stage, and 32ha in development. A total of 690 whimbrels were detected in the two survey rounds, with majority of detections in harvest stage fields (N=637, 92%), and 53 detections (8%) in either growth or development stage. A total of 565 (82%) whimbrels detected during survey round 1, and 125 (18%) during survey round 2. The Acadian Peninsula of New Brunswick, Canada appears to support a significant portion of the total whimbrel population that uses Atlantic Canada in fall migration. Over 99% of all whimbrels detected during the aerial, ground, and evening roost surveys originated from blueberry fields, suggesting that tidal influences on behavior are negligible. Warden pressure on the whimbrels in the blueberry fields is quite high and needs to be addressed.
