Effects of Mowing on Anthraquinone for Deterrence of Canada Geese and Survey of Canada Goose Fecal Contaminants
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Date
2009-08-03
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Abstract
Resident Canada goose (Branta canadensis) populations have increased in urbanizing regions of the eastern United States, where man-made ponds and lakes surrounded by managed turfgrass offer ideal habitats. High concentrations of geese in these areas may cause feces accumulation, outbreaks of zoonotic diseases, eutrophication of adjacent waterways, and spread of turfgrass weeds. Although repellents effectively deter geese from turfgrass areas, frequent mowing (e.g., as in corporate parks and golf courses) may impact the efficacy of repellents. We tested the effect of 2 different mowing schedules on the longevity of FlightControl® PLUS (FCP), an anthraquinone based avian digestive irritant. From June 2007 to October 2008, we conducted 4, 30-day experiments of repellent efficacy on free-ranging geese at 8 sites. Sites were divided into 4 0.1-ha plots, each containing a unique treatment of the repellent (treated or untreated) and mowing frequency (4-day or 8-day). Each experimental session consisted of a 7-day pretreatment period of baseline observations and 30 days of post-treatment observations. Goose droppings were collected daily from transects in each plot, and percent of grass with FCP remaining was measured daily. Also, we tested 234 droppings for Giardia lamblia using a ProSpect Giardia EZ Microplate Assay, measured amounts of nitrogen (TKN) and phosphorus (TP) in 304 fecal samples, and observed 127 potted droppings for plant germination in a greenhouse. On average, goose use of FCP treated plots was lower than on untreated plots for 30 days. Over the 30 day period, goose use and FCP coverage was similar between treated plots mowed every 4 and 8 days. Further, the average FCP coverage on grass blades in treated plots decreased steadily from approximately 95% to 10%. None of the fecal samples tested positive for Giardia. The average amounts of TKN and TP in fecal samples were 24.2 mg/g (range = 12.6 – 55.7) and 3.6 mg/g (range = 1.4 – 8.3) of dry matter, respectively, with an average of 4,318.0 g/ha/day deposited by ≈42 geese. No controls germinated plants, whereas 4 (3.1%) fecal samples germinated plants: Pennsylvania smartweed (Polygonum pennsylvanicum L.), annual bluegrass (Poa annua L.), and 2 Kyllinga spp. FlightControl® PLUS effectively repelled Canada geese, but longevity of the chemical depends on keeping treated blades alive and under mowing height. Transmission of G. lamblia by Canada geese does not appear to be a high risk. Resident Canada goose droppings at our study sites contribute 17 – 31% of recommended N and 17 – 38% of recommended P in lawn fertilization rates. Kyllinga spp. and annual bluegrass are turfgrass weeds; however the low percentage of germinations indicates little risk of turf-feeding Canada goose weed dispersal. I recommend using FCP on areas of highest goose concentration before and when they are most prevalent. This should be done along with reduction of palatable turfgrass and annual lethal reductions. Fertilization rates should be adjusted depending on the number of geese present and the concentration of their droppings in order to save money and prevent eutrophication. Periodic testing of goose droppings for Giardia lamblia and weed seeds may prevent infestations. Research is needed to find the optimal mowing rate to keep treated blades alive and below mowing height. Information on the movements of resident Canada geese will be important for management of free-ranging populations. Identifying or developing turfgrasses that are unpalatable to Canada geese would be highly useful. If geese test positive for Giardia sp. cysts, trophozoites should be collected to identify species. The alternative to this method is to develop species specific assays. Also, research is needed on the result of resident Canada goose fecal nitrogen and phosphorus deposition on adjacent water quality.
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fecal contaminants, giardia, Canada goose, Branta canadensis, avian repellents, seed dispersal, nutrient loading
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MS
Discipline
Fisheries and Wildlife Sciences
