Seasonal habitat selection and movements by mottled ducks

Abstract

ABSTRACTMottled ducks (Anas fulvigula) were released by the South Carolina Department of Natural Resources (SCDNR) in South Carolina, USA, during 1975–1983 and expanded into Georgia, USA, in the 1990s. Banding data suggest that birds marked in Georgia are often harvested in other states. Because the South Carolina reintroduced population was able to expand into Georgia via long‐distance dispersal, a more thorough understanding of mottled duck spatial ecology in Georgia and South Carolina is needed to direct future management decisions to accommodate expanding duck populations. We used global positioning system (GPS) telemetry to investigate movements and habitat selection by 47 mottled ducks (17 males, 30 females) during 4 seasons from 2013–2016. Mean seasonal home ranges varied from 2,002–4,598 ha across sexes and seasons. We found mean distances moved within seasonal ranges varied from 3.5–11.3 km/day for birds captured in Georgia, and 1.3–5.6 km/day for those captured in South Carolina. We observed 23 excursions, in which individuals left established seasonal ranges for >6 hours and moved ≥5 km; these excursions ranged from 5 km to 139.5 km. We documented 5 dispersals ranging from 52.6 km to 245.8 km. We also documented several long‐distance movements, with 7 birds captured in Georgia moving to South Carolina and 2 moving to Florida, USA. These movements suggest mottled ducks in South Carolina and Georgia may constitute a single population. Notably, we observed dispersal and long‐distance movements only from birds marked in Georgia, suggesting that habitat may be a limiting factor along the Georgia coast. We quantified third‐order selection for mottled ducks and found seasonal selection for managed impoundments and avoidance of palustrine emergent marsh during breeding and teal seasons. Managed impoundments were limited to 4 river systems along coastal Georgia and South Carolina, resulting in much of the coastal wetlands in both states being unused by mottled ducks. We suggest the Georgia Department of Natural Resources (GADNR) and SCDNR work cooperatively to manage mottled ducks and their habitats by focusing efforts to create and manage impoundments throughout the Santee, Savannah, Altamaha, and Ashepoo‐Combahe‐Edisto (ACE) river basins in coastal Georgia and South Carolina where we documented use. © 2018 The Wildlife Society.