Origins of harvested Mallards from Lake St. Clair, Ontario: a stable isotope approach

• Published in: Avian conservation and ecology Vol. 14; no. 2; p. 3
• Main Authors: Palumbo, Matthew D., Tozer, Douglas C., Hobson, Keith A.
• Format: Journal Article
• Language: English
• Published: Waterloo Resilience Alliance 01.12.2019
• Subjects: Anas platyrhynchos; Bayesian analysis; Birds; Breeding; Conservation; deuterium; Feathers; Females; harvest management; Hatching; Hunting; Hydrogen isotopes; isoscapes; Isotopes; Lakes; Latitude; Males; mallard; Management; Molting; Moulting; Origins; Plumes; Probability theory; Stable isotopes; Waterfowl
• ISSN: 1712-6568; 1712-6568
• DOI: 10.5751/ACE-01389-140203

Determining origins of waterfowl is important for establishing appropriate management and conservation strategies. In North America, much information is available from long-term mark-recapture programs involving banding on breeding or molting grounds. However, this approach is less able to identify origins of individuals across broad areas where banding effort is low. We used stable-hydrogen isotope analyses of feathers (δ2Hf) from Mallards (Anas platyrhynchos) harvested during the 2014-2015 and 2015-2016 hunting seasons at Lake St. Clair (LSC), Ontario, Canada (n = 237 individuals). We created a feather isoscape and applied Bayesian assignment approaches to determine probability of origin. The proportion of hatch-year Mallards produced locally, i.e., at the same latitude as LSC, as opposed to farther north or south of LSC, ranged from 13.1% to 22.0% with almost no difference by sex. The proportion of after-hatch-year (AHY) birds that molted locally ranged from 3.5% to 11.7%, with slightly fewer local AHY females compared with local AHY males. Nearly all birds that did not originate locally came from latitudes to the north of LSC, and only 2 from south of LSC. Whether this pattern is representative of locations in the Great Lakes beyond our study area is unknown but is of great relevance for harvest management. As such, we are expanding our study with plans to examine isotope-based origins of Mallards and other harvested waterfowl species at locations throughout the Great Lakes region. Because of its unique potential to fill knowledge gaps, we advocate the use of the stable isotope technique in the management of North American waterfowl and encourage more research in this area.