Site selection by geese in a suburban landscape

Background In European and North American cities geese are among the most common and most visible large herbivores. As such, their presence and behaviour often conflict with the desires of the human residents. Fouling, noise, aggression and health concerns are all cited as reasons that there are “too many”. Lethal control is often used for population management; however, this raises questions about whether this is a sustainable strategy to resolve the conflict between humans and geese when, paradoxically, it is humans that are responsible for creating the habitat and often providing the food and protection of geese at other times. We hypothesise that the landscaping of suburban parks can be improved to decrease its attractiveness to geese and to reduce the opportunity for conflict between geese and humans. Methods Using observations collected over five years from a botanic garden situated in suburban Belgium and data from the whole of Flanders in Belgium, we examined landscape features that attract geese. These included the presence of islands in lakes, the distance from water, barriers to level flight and the size of exploited areas. The birds studied were the tadornine goose Alopochen aegyptiaca (L. 1766) (Egyptian goose) and the anserine geese, Branta canadensis (L. 1758) (Canada goose), Anser anser (L. 1758) (greylag goose) and Branta leucopsis (Bechstein, 1803) (barnacle goose). Landscape modification is a known method for altering goose behaviour, but there is little information on the power of such methods with which to inform managers and planners. Results Our results demonstrate that lakes with islands attract more than twice as many anserine geese than lakes without islands, but make little difference to Egyptian geese. Furthermore, flight barriers between grazing areas and lakes are an effective deterrent to geese using an area for feeding. Keeping grazing areas small and surrounded by trees reduces their attractiveness to geese. Conclusion The results suggest that landscape design can be used successfully to reduce the number of geese and their conflict with humans. However, this approach has its limitations and would require humans to compromise on what they expect from their landscaped parks, such as open vistas, lakes, islands and closely cropped lawns.


Background
In European and North American cities geese are among the most common and most visible large herbivores. As such, their presence and behaviour often conflict with the desires of the human residents. Fouling, noise, aggression and health concerns are all cited as reasons that there are "too many". Lethal control is often used for population management, however, this raises questions about whether this is a sustainable strategy to resolve the conflict between humans and geese, when paradoxically, it is humans that are responsible for creating the habitat and often providing the food and protection of geese at other times. We hypothesise that the landscaping of suburban parks can be improved to decrease its attractiveness to geese and to reduce the opportunity for conflict between geese and humans.

Methods
Using observations collected over five years from a botanic garden situated in suburban Belgium and data from the whole of Flanders in Belgium, we examined landscape features that attract geese. These included the presence of islands in lakes, the distance from water, barriers to level flight and the size of exploited areas. The birds studied were the tadornine goose Alopochen aegyptiaca (L. 1766) (Egyptian goose) and the anserine geese, Branta canadensis (L. 1758) (Canada goose), Anser anser (L. 1758) (greylag goose) and Branta leucopsis (Bechstein, 1803) (barnacle goose). Landscape modification is a known method for altering goose behaviour, but there is little information on the power of such methods with which to inform managers and planners.

Results
Our results demonstrate that lakes with islands attract more than twice as many anserine geese than lakes without islands, but make little difference to Egyptian geese. Furthermore, flight barriers between grazing areas and lakes are an effective deterrent to geese using an area for feeding. Keeping grazing areas small and surrounded by trees reduces their attractiveness to geese.

Conclusion
The results suggest that landscape design can be used successfully to reduce the number of geese and their conflict with humans. However, this approach has its limitations and would require humans to compromise on what they expect from their landscaped parks, such as open vistas, lakes, islands and closely cropped lawns.
138 between two and four times a month during the growing season, though small areas are 139 maintained as wildflower meadows and are cut once or twice a year. All geese in the Garden 140 are considered either non-native or feral. All species breed in the Garden, though the breeding 141 of Canada geese is, in part, controlled by egg-shaking. The birds using the Garden are part of a 142 larger population of geese that inhabit the greater Brussels area, and birds move in and out of 253 Quantification of the length of geese droppings showed a clear edge effect at the border to 254 woodland (Fig. 2). A shorter length of droppings was found close to the woodland, but this 255 effect only extended 5-10 m from the boundary.
256 As a control modelling was also performed in parallel to the woodland boundary, but models 257 either failed to converge or showed no directional trend. Manuscript to be reviewed 265 particular are far more wide-ranging than other species notably in the large western sectors.
266 The models of sector usage were evaluated with various means. The Cook's distance was used 267 to evaluate if particular sectors had an exaggerated influence on the model outcomes, but this 268 does not appear to be the case (Fig. S1). Variograms of the residuals did not show evidence for 269 spatial autocorrelation that was not accounted for in the model parameters (Figs S2-S5). A plot 270 of residuals versus fitted values indicates that there may be some non-linearity between the 271 predictors and the abundance of geese, but this was not clear (Fig. S6). The Q-Q plot shows that 272 the residuals were quite normally distributed for all models (Fig. S7). The Scale-Location plot 273 showed that some heteroscedasticity was evident in all models, however we consider that only 274 the model for B. leucopsis was so heteroscedastic that it might impact our interpretation of the 275 results. Given that no real-world model will perfectly match our assumptions and some of the 276 reasons for deviation from these assumptions are suggested in the discussion. 306 Lakes with islands attract more Canada, greylag and barnacle geese in the summer (Fig. 4). 307 These results indicate that a lake without an island had 35%-60% fewer anserine geese than a  (Fig. 1, Fig. 2, Table   314 1). A casual observer could assume that there is a rather passive relationship between geese 315 and their landscape, but as with any other animal, geese are clearly actively selecting and using 316 particular landscapes and landscape features suited to their preferences.
317 Edge effects are relevant to the usage of geese on lawns because they reduce the active area of 318 use for the geese. Our methodology did not distinguish whether there are species differences, 319 however, the effect was so distinct that we speculate that all species are influenced. While 320 there may be many potential causes of an edge effect, such as predator avoidance and poorer 321 grazing, an area of lawn less than 20 m in diameter is likely to be undesirable to geese. 322 However, with increasing ratio of area to circumference means that the relevance of this effect 323 will diminish with increasing area. In ornamental parks individual specimen trees might extend 324 the influence of this edge effect. 325 326 Sector area was the most consistent predictor of goose abundance (Table 1). This was 327 anticipated, as more space can contain more geese. Yet in addition to the edge effects there 328 are reasons to expect a more sophisticated relationship between goose number and area.