Effects of agricultural change on abundance, fitness components and distribution of two arctic‐nesting goose populations

Abstract

Intensification of agriculture since the 1950s has enhanced the availability, competitive ability, crude protein content, digestibility and extended growing seasons of forage grasses. Spilled cereal grain also provides a rich food source in autumn and in winter. Long-distance migratory herbivorous geese have rapidly exploited these feeding opportunities and most species have shown expansions in range and population size in the last 50 years. Results of long-term studies are presented from two Arctic-breeding populations, the Svalbard pink-footed goose and the Greenland white-fronted goose (GWFG). GWFGs have shown major habitat shifts since the 1950s from winter use of plant storage organs in natural wetlands to feeding on intensively managed farmland. Declines in local density on, and abandonment of, unmodified traditional wintering habitat and increased reproductive success among those birds wintering on farmland suggest that density-dependent processes were not the cause of the shift in this wintersite-faithful population. Based on enhanced nutrient and energy intake rates, we argue that observed shifts in both species from traditionally used natural habitats to intensively managed farmland on spring staging and wintering areas have not necessarily been the result of habitat destruction. Increased food intake rates and potential demographic benefits resulting from shifts to highly profitable foraging opportunities on increasingly intensively managed farmland, more likely explain increases in goose numbers in these populations. The geographically exploratory behaviour of subdominant individuals enables the discovery and exploitation of new winter feeding opportunities and hence range expansion. Recent destruction of traditional habitats and declines in farming at northern latitudes present fresh challenges to the well being of both populations. More urgently, Canada geese colonizing breeding and moulting habitats of white-fronted geese in Greenland are further affecting their reproductive output.

Landscape structure, human disturbance and crop management affect foraging ground selection by migrating geese

“…Other authors have also found that geese preferentially forage in larger fields (e.g. Gill 1996;McKay et al 2006) as well as in more intensively used farmland (Fox et al 2005). However, we are not aware of any earlier studies showing that crop diversity negatively affected foraging site choice by geese during migration.…”

“…However, we are not aware of any earlier studies showing that crop diversity negatively affected foraging site choice by geese during migration. Thus, geese are one of the few examples of species which may benefit from intensive agriculture (Van Eerden et al 1996;Fox et al 2005). However, site choice by geese is inevitably different from that of the declining populations of farmland birds which are mostly territorial during the breeding season.…”

“…However, much less attention has been paid to species that select various farmland habitats during migration (Lindström et al 2010). Moreover, there are several bird species that might benefit from intensive agricultural landscapes during migration, such as the Golden Plover Pluvialis apricaria (Lindström et al 2010), the Common Crane Grus grus (Leito et al 2008) and geese (e.g., Fox et al 2005; Van der Graaf et al 2007;Jensen et al 2008), and which in turn may have important impacts on ecosystem processes and the agro-economy. Consequently, understanding how such migratory birds select foraging sites during migration is desirable (Lindström et al 2010;Sebastian-González et al 2010;Batáry et al 2011).…”

Philopatry in a changing world: response of pink-footed geese Anser brachyrhynchus to the loss of a key autumn staging area due to restoration of Filsø Lake, Denmark

“…The relative ease with which pinkfooted geese have been able to adapt to the loss of the Filsø feeding site points to substantial cognitive plasticity that likely relates to its habitat use (Madsen 2001). The switch to an agricultural diet characteristic of both this population (Fox et al 2005) and other species of geese (Rosin et al 2012) opened the door to an almost inexhaustible food resource in the Danish landscape, and the availability of staging sites during the autumn migration may therefore depend more strongly on the relative proximity of secure roosting areas rather than specific food resources. As a consequence, philopatric waterfowl species exploiting cultivated areas might be much less susceptible to changes in staging areas than species targeting specific food sources much less available in a modern landscape (Clausen et al 2012;Fox et al 2011;Wang et al 2012).…”

“…The population currently totals 76,000-81,000 birds (2013)(2014), and has been steadily increasing over the last decades . During the non-breeding period, pink-footed geese forage most commonly on energy-rich agricultural plant matter such as waste grain on cereal stubble fields, newly sown winter cereals, pastures, and newly sown spring cereal grain fields (Fox et al 2005). Like other goose species, they prefer open areas that allow sufficient look-out for potential dangers (Madsen 1985a;Rosin et al 2012).…”