Tannins in Puccinellia arctica: possible deterrents to herbivory by Canada geese.

Urban populations of Canada geese, Branta canadensis, pose a nuisance problem throughout most of the eastern United States and in other parts of the United States and Canada. Puccinellia arctica is a species of arctic grass that is unpalatable to Canada geese on the North Slope of Alaska and may prove to be an effective long-term and nonlethal means of controlling the growing populations of urban Canada geese. A comparative study of the secondary metabolites of both P. arctica and Puccinellia langeana and Poa pratensis, two palatable grass species that Canada geese generally consume, revealed no significant differences. However, ellagitannin levels were higher in P. arctica than in the palatable grass species and may be contributing to its unpalatability to Canada geese. These results support the potential to use P. arctica in public areas to control geese intrusions.