Article

Primary productivity and anthropogenic disturbance as determinants of Upland Goose Chloephaga picta distribution in southern Patagonia

Ibis (Impact Factor: 2.36). 06/2011; 153(3):517 - 530. DOI: 10.1111/j.1474-919X.2011.01127.x

ABSTRACT A species distribution may be determined by its responses to patterns of human disturbance as well as by its habitat preferences. Here we investigate the distribution of the Upland Goose Chloephaga picta, which has been historically persecuted by farmers and ranchers in Patagonia because it feeds on crops and pastures and is assumed to compete with sheep for forage. We assess whether its current breeding distribution is shaped by persecution by ranchers or whether it can be better explained by differences in habitat primary productivity and preference for wetlands, or by other anthropogenic disturbances not associated with ranching. We built species distribution models to examine the relative effect of environmental and anthropogenic predictors on the regional distribution of Upland Goose. We performed vehicle surveys in the province of Santa Cruz, Argentina, in two years, surveying 8000 km of roads and recording 6492 Geese. Generalized additive models were used to model the presence/absence of Geese in 1-km cells. The models suggested that Upland Goose distribution is not currently affected by rancher control, as the species is more abundant in areas with high sheep stocking levels, but it is positively influenced by primary productivity and negatively influenced by urban areas. Anthropogenic disturbance caused by urban areas and oil extraction camps had a greater impact in limiting the species distribution than sheep ranching.

1 Bookmark
 · 
40 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: When approached by humans, virtually all species flee, but we lack an understanding of the factors that influence flight response among species. Understanding this variation may allow us to understand how ‘fear’ structures communities, as well as to predict which species are likely to coexist with humans. I used flight initiation distance (FID) as a comparative metric of wariness and examined the relative importance of life history and natural history traits in explaining variation in FID in 150 species of birds. In a series of comparative analyses, I used independent contrasts to control for phylogenetic similarity and regressed continuous life history traits against flight initiation distance. Body size had a large and significant effect in explaining variation in flightiness: larger species initiated flight at greater distances than smaller species. After controlling for variation explained by body size, there was a nonsignificant positive relation between the age of first reproduction and FID. There were no relations between FID and clutch size, number of days spent feeding young, longevity, or habitat density. I used concentrated changes tests to look for evidence of coevolution between flightiness and dichotomous traits. Flightiness evolved multiple times and some clades were flightier than others. Flightiness was more likely to evolve in omnivorous/carnivorous species and in cooperatively breeding species. These results suggest that body size and age of first reproduction are important in explaining variation in disturbance tolerance in birds, and that species that capture live prey and those that are highly social are relatively wary. The results suggest a novel mechanism of how anthropogenic disturbance may contribute to extinction.
    Animal Behaviour. 02/2006;
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: We studied the community richness and dynamics of birds in landscapes recently affected by urbanization to test the prediction that biotic communities living in degraded landscapes are increasingly composed of generalist species. We analyzed bird communities in 657 plots monitored by the French Breeding Bird Survey from 2001 to 2005, accounting for the probability of species detection and spatial autocorrelation. We used an independent land-cover program to assess urbanization intensity in each FBBS plot, from 1992 to 2002. We found that urbanization induced community homogenization and that populations of specialist species became increasingly unstable with increasing urbanization of the landscape. Our results emphasize that urbanization has a substantial impact on the spatial component of communities and highlight the destabilizing effect of urbanization on communities over time. These results illustrate that urbanization may be a strong driving force in functional community composition and that measuring community homogenization is a powerful tool in the assessment of the effects of landscape changes and thus aides sustainable urban planning.
    Conservation Biology 07/2007; 21(3):741-51. · 4.36 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Tourism in the Arctic archipelago of Svalbard, Norway, has increased significantly in the last decade. Cruise ships make landings all around the archipelago, and there are numerous snowmobile, boat and hiking excursions. We describe disturbance effects on the three geese species that breed in Svalbard: the pink-footed goose (Anser brachyrhynchus), the barnacle goose (Branta leucopsis) and the light-bellied brent goose (Branta bernicla hrota). All three are regarded as highly vulnerable to disturbance. Behavioural responses by geese to humans on foot were analysed by estimating the distances at which geese become alerted, the escape flight distances and the length of escape flights, during pre-nesting, nesting and brood-rearing periods. We evaluate the consequences of human intrusion on the reproductive success in breeding colonies. During all three phases, pink-footed geese responded at longer ranges, and flew/ran longer distances, than both brent and barnacle geese: when disturbed on the nest site, both male and female pink-footed geese flew far away, resulting in a high rate of nest loss to avian predators (35%), compared with the 4 and 0% losses among barnacle and brent geese, respectively. During brood rearing, families of pink-footed geese escaped at an average distance of 1717 m, compared with distances of 620 and 330 m for brent and barnacle geese, respectively. Even though bird sanctuaries have been established on several islets, with no human access during nesting, many core areas for the three species remain without restrictions, such as islets used by brent geese and slopes and valleys with nesting pink-footed geese, brood-rearing areas and moulting grounds for non-breeding geese. We propose regulations of human access to goose concentration areas, and address the need to better protect these significant areas. We also discuss the need for further research on the vulnerability of geese to human activity.
    Polar Research 11/2009; 28(3):376 - 389. · 1.62 Impact Factor

Full-text

View
11 Downloads
Available from
May 15, 2014