Migration Ecology of American Woodcock Arkansas Cooperative Research Unit RWO 43 Annual Report 2015

American woodcock (Scolopax minor) are a species of conservation concern across eastern North America. Results from the Singing-ground Survey, an index used to monitor woodcock populations, show long-term declines across the species’ range (Cooper and Rau 2014). Understanding American woodcock migration as it relates to population ecology is a highpriority information need–in part, because the migratory period is believed to be a period of high mortality (D.J. Case and Associates 2010). The current understanding of woodcock migration ecology has been limited by available technology such as VHF telemetry, bandrecovery, and wing collection survey data (Myatt and Krementz 2007a, 2007b). Recent developments in the miniaturization of satellite transmitters (PTTs) now allow satellite telemetry of American woodcock. We are deploying PTTs on woodcock in their breeding and wintering grounds of the Central Management Region, an area with boundaries similar to that of the Mississippi Flyway (Coon et al 1977, Cooper and Rau 2014). This will allow us to document timing of migration initiation, rate of migration, stopover length, routes taken, and final destination for both spring and fall migration, and to describe land use characteristics at migratory stopover sites.

In fall 2013, we initiated a pilot project evaluating the use of satellite transmitters (PTTs) to investigate woodcock migration ecology. We refurbished seven 9.5 g PTTs available to us and, with an exception from the U.S. Geological Survey Bird Banding Laboratory regarding transmitter mass restrictions, deployed these PTTs on adult female woodcock with mass >200 g. We attached PTTs using a modified thigh harness (Rappole and Tipton 1991). Woodcock were trapped using night-lighting with hand nets and mist-netting techniques (McAuley et al. 1993). We deployed PTTs on females captured at Tamarac National Wildlife Refuge in northwest Minnesota September 2013 (n = 1), Sherburne Wildlife Management Area in Louisiana January 2014 (n = 4), and Ozark National Forest in northwest Arkansas March 2014 (n =1). With the exception of one marked female in Louisiana, which we believe was killed by an owl upon release, all females (n = 5) successfully migrated; the Minnesota female migrated both during the fall and spring. All females (n = 3) marked in Louisiana migrated to the Eastern Management Region whereas the Arkansas and Minnesota females migrated within the Central Management Region (Fig. 1). We deployed three additional 9.5 g PTTs on American woodcock at Sherburne National Wildlife Refuge, Minnesota during fall 2014. We also received data during fall migration from three of the PTTs previously deployed. These woodcock reached locations in Texas, Louisiana, Mississippi, Missouri, Tennessee, and Virginia. Our initial results suggest: (1) that larger females can successfully migrate with a 9.5 g PTT, (2) that the harness attachment method does not inhibit ‘normal’ migration, and (3) that the 9.5 g solar-powered units are receiving sufficient light energy to recharge the battery.

In January 2015 we were able to acquire ten 5 g PTTs. The 5 g PTTs, recently developed by Microwave Telemetry, are in theory preferable to the 9.5 g units. Their reduced size allows us to deploy units on any woodcock greater than 150 g (instead of only females >200 g), however had concerns whether the smaller unit will receive enough light energy to charge the battery. In January and February of 2015 we deployed three 9.5 g and four 5 g PTTs in Texas, and five 9.5 g and six 5 g PTTs in Louisiana. In spring of 2015, we recorded 15 successful migrations from Texas and Louisiana. These woodcock are spread among 10 states and provinces in the breeding grounds: South Dakota, Minnesota, Wisconsin, Michigan, New York, Vermont, Maine, New Brunswick, Quebec and Ontario (Fig. 1). The 5 g units had higher failure rates and recorded fewer locations than the 9.5 g PTTs. We discontinued their use after this season.