Potential Range Expansion of Buffleheads
Buffleheads (Bucephala albeola) predominantly nest in the boreal forests and aspen parklands of Canada and Alaska, with the highest densities found in central British Columbia (Campbell et al. 1990). Although buffleheads are common fall and spring migrants throughout much of Minnesota, they are considered rare residents during the summer (Janssen 1987; Gauthier 1993). However, in 1985 Agassiz National Wildlife Refuge (NWR) in northwest Minnesota recorded its first brood of buffleheads. Since then, the number of nesting pairs and broods has increased with an estimated 200 pairs breeding in and around the 61,500 acre refuge (~25,000 ha) over the past five years. Only a few other breeding observations have been reported across Minnesota (Figure 2), despite many areas having habitat similar to Agassiz NWR.
Buffleheads are a secondary cavity-nesting species which frequently use the cavities of northern flickers (Colaptes auratus) and, to a lesser extent pileated woodpeckers (Dryocopus pileatus). Nest cavities used by buffleheads are most commonly in live and dead poplar or aspen trees (Populus spp.). They also will use nest boxes (Gauthier 1988).
The aims of our study are to examine the range and magnitude of bufflehead breeding activity in northwestern Minnesota, and to characterize landscape features associated with nesting pairs and broods. Although Agassiz NWR has detailed records on the increase in bufflehead breeding activity, the extent of use of other wetland complexes in northwestern Minnesota by breeding buffleheads is currently unknown. In May of 2012 and 2013, we conducted aerial and ground breeding pair surveys for buffleheads at five wetland sites with documented bufflehead breeding activity and five wetland sites with potentially suitable habitats, but no known bufflehead breeding occurrences. This work was conducted within a five-county portion of northwestern Minnesota. Additionally, we are conducting brood counts in July and August at these same sites to estimate productivity.
Campbell, R. W., N. K. Dawe, I. McTaggart-Cowan, J. M. Cooper, G. W. Kaiser, and M. C. E. McNall. 1990. The Birds of British Columbia. Vol. 1. R. British Columbia Museum, Victoria.
Gauthier, G. 1988. Wildl. Soc. Bull. 16:132-141.
Gauthier, G. 1993. Bufflehead (Bucephala albeola), The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Lab of Ornithology; Retrieved from the Birds of North America Online: http://bna.birds.cornell.edu/bna/species/067doi:10.2173/bna.67.
Janssen, R. B. 1987. Birds in Minnesota. Published by the University of Minnesota Press for the James Ford Bell Museum of Natural History, Minneapolis, MN.
- Gregg Knutsen - Agassiz National Wildlife Refuge Biologist, U.S. Fish & Wildlife Service
- Cassie Skaggs - Lead Technician