Does intensive goose grazing affect breeding waders?

Abstract

Increasing goose population sizes gives rise to conflicts with human socioeconomic interests and in some circumstances conservation interests. Grazing by high abundances of geese in grasslands is postulated to lead to a very short and homogeneous sward height negatively affecting cover for breeding meadow birds and impacting survival of nests and chicks. We studied the effects of spring grazing barnacle geese Branta leucopsis and brent geese Branta bernicla on occupancy of extensively farmed freshwater grasslands by nesting and brood‐rearing waders on the island Mandø in the Danish Wadden Sea. We hypothesized that goose grazing would lead to a shorter grass sward, negatively affecting the field occupancy by territorial/nesting and chick‐rearing waders, particularly species preferring taller vegetation. Goose grazing led to a short grass sward (<5 cm height) over most of the island. To achieve a variation in sward height, we kept geese off certain fields using laser light. We analyzed effects of field size, sward height, mosaic structure of the vegetation, proximity to shrub as cover for potential predators, and elevation above ground water level as a measure of wetness on field occupancy by nesting and chick‐rearing waders. The analysis indicated that the most important factor explaining field occupancy by nesting redshank Tringa totanus, black‐tailed godwit Limosa limosa, oystercatcher Haematopus ostralegus and lapwing Vanellus vanellus as well as by chick‐rearing black‐tailed godwit and lapwing was short vegetation height. Distance to shrub cover and elevation were less important. Hence, despite very intensive goose grazing, we could not detect any negative effect on the field occupancy by nesting nor chick‐rearing waders, including redshank and black‐tailed godwit, which are known to favor longer vegetation to conceal their nests and hide their chicks. Possible negative effects may be buffered by mosaic structures in fields and proximity to taller vegetation along fences and ditches.

Selection of a diversionary field and other habitats by large grazing birds in a landscape managed for agriculture and wetland biodiversity

“…However, there are also findings of absence of negative impact on breeding waders due to goose grazing (Madsen et al, 2019) and of common cranes on the abundance of other peatland bird species (Fraixedas et al, 2020). Considering our findings and the presence of flocks of hundreds or thousands of common cranes and greylag geese in the protected area, we anticipate that there is a high risk for negative impacts, but also a need for further scientific studies to…”

“…Similar concerns have been raised for the effects of high abundance of geese, as overgrazing of reed beds in wetlands and pastures may affect both flora and bird fauna negatively (Bakker et al., 2018). However, there are also findings of absence of negative impact on breeding waders due to goose grazing (Madsen et al., 2019) and of common cranes on the abundance of other peatland bird species (Fraixedas et al., 2020). Considering our findings and the presence of flocks of hundreds or thousands of common cranes and greylag geese in the protected area, we anticipate that there is a high risk for negative impacts, but also a need for further scientific studies to assess whether these have effects on population dynamics of wetland bird species or irreversible effects on the vegetation.…”

“…In addition to the challenges of crop damage, high densities of large grazing birds may be negative for sensitive ecosystems and biodiversity. For example, geese have been shown to have both significant negative effects on reed beds, wet meadows, and tundra vegetation due to overgrazing (Bakker et al., 2018; Kuijper et al., 2006; Moonen et al., 2023; Samelius & Alisauskas, 2009) and potentially also on nest success for meadow‐breeding wader (Madsen et al., 2019; Moonen et al., 2023). There is also growing concern that predation by common cranes on eggs and chicks of other species may affect threatened wetland birds negatively (Sandgren, 2019; Wirdheim, 2019).…”

Effects of grazing on underground parts of marsh plants by wintering Middendorf's bean goose Anser fabalis middendorffii: Its role as a keystone species in plant communities

“…This occurs through direct foraging of plants (Bakker et al, 2018; Bjerke et al, 2021; Gauthier et al, 1996; Mulder & Ruess, 2001), changes in nutrient cycling due to their feces (Dingemans et al, 2011; Ganning & Wulff, 1969), and reducing plant litter (Wallin & Milberg, 1995; Zacheis et al, 2001). At breeding sites, geese may have pronounced heavy impacts on the vegetation (Fox et al, 2017; Madsen et al, 2019; Vickery & Gill, 1999). In the Arctic zone, grubbing and grazing by Lesser Snow Goose Anser caerulescens caerulescens or Pink‐footed Goose A. brachyrhynchus have completely shifted the vegetation into a state of low diversity (Chang et al, 2001; Jefferies, 1988; Jefferies et al, 2004; Jefferies & Rockwell, 2002; Pedersen et al, 2013).…”

Chromosome-level genome assembly of goose provides insight into the adaptation and growth of local goose breeds

“…Physical characteristics and features vary significantly among species, making the Anatidae family rich in diversity and specificity. Anatidae adults are usually herbivores, feeding on a variety of aquatic plants, which are well suited to sustainable production practices, thereby reducing competition for human food, and some species are even used for cropping weeds and pest control [ 1 , 2 ]. For a long time, duck and goose feathers have been popular in pillows, quilts, and coats [ 3 ].…”