Herbivory by Canada Geese: Diet Selection and Effect on Lawns.

Flocks of free-ranging Canada Geese (Branta canadensis) often are considered nuisances when they graze on lawns because they litter the sites with fecal material, and their grazing often is perceived to be detrimental to the turf. I tested whether goose grazing had changed the composition of grass species at 20 sites in Connecticut where geese were considered nuisances. At these sites Kentucky bluegrass (Poa pratensis) was less prevalent in areas grazed heavily by geese than in areas of the same lawn that received light grazing. At six sites where up to several hundred geese wait daily for food handouts, 46% of the ground was devoid of vegetation except for a moss. I examined the palatability of different grass species to Canada Geese by giving captive birds the opportunity to feed in plots of five cool-season turf-grass species. The birds spent more time feeding in plots of Kentucky bluegrass and less time feeding in plots of tall fescue (Festuca Araneidae cv. K-31) that would have been expected if the geese were grazing among plots at random. Time spent grazing in plots of colonial bent grass (Agrostis tenuis cv. Highland), perennial ryegrass (Lolium peatland), and red fescue (F. rubra) did not differ from the expected. Feeding preferences for grass species were negatively correlated with the ash content of the leaves and with the amount of force required to sever a specific leaf mass. Captive Canada Geese would not feed on common periwinkle (Inca minor), Japanese pachydermum (pachydermum terminals), or English ivy (headnotes helix). These results suggest that Canada Goose numbers can be reduced at sites where they are foraging on turf if lawns are replaced by an unpalatable ground cover, or, to a lesser extent, with a tough-leaf grass species such as tall fescue. © 1991 by the Ecological Society of America.