Expensive Traditions: Energy Expenditure of Aleutian Geese in Traditional and Recently Colonized Habitats

Abstract

In an effort to reduce goose depredation at a traditional spring migratory stopover site, private landowners implemented a coordinated hazing plan to scare Aleutian cackling geese (Branta hutchinsii leucopareia) from private lands to adjacent public pastures that were cultivated and set aside specifically for geese. Coincidentally, some Aleutian geese began using a new stopover site 150 km farther south in their spring migratory range; numbers at the new site continue to increase. We tested the idea that when their ability to acquire resources deteriorates geese are likely to seek improved foraging conditions, especially during spring migration when individuals strive to maximize nutrient stores and minimize energy expenditure. We quantified measures of goose foraging performance in traditional and new spring staging sites by calculating foraging opportunity, foraging effort, body condition, and daily energy expenditure. Geese staging at the site with higher levels of human disturbance had less foraging opportunity and, despite increased foraging effort and more nutritious food‐plants at the site, birds there experienced an elevated energy expenditure and poorer body condition than birds at the new stopover site. Reduced foraging time and increased energy expenditure at the traditional spring staging site may have triggered the colonization process. Suitability assessment of habitat for migratory geese should include measures of foraging opportunity, disturbance risks, and daily energy expenditure in addition to quantity and quality of foods.

BIODIVERSITY RESEARCH: Soil moisture limits foraging: a possible mechanism for the range dynamics of the hadeda ibis in southern Africa

“…BMR is a measure of the minimum resting metabolic rate in the thermoneutral zone when the animal is inactive. We therefore multiplied this number by 3.2 (average multiple of BMR yielding actual energy expenditure of birds with activity patterns similar to hadedas, Mini & Black, 2009) to get an estimate of the number of hours required to meet daily energy expenditure (Fig. 3).…”

“…obs), but the energy requirements for walking are not well known. We chose a factor of 3.2 based on a study on Aleutian cackling geese ( Branta hutchinsii leucopareia ), which appear to be similar to hadedas in mass (geese: 1.55 kg; hadeda: 1.3 kg) and activity (Mini & Black, 2009).…”

“…obs), but the energy requirements for walking are not well known. We chose a factor of 3.2 based on a study on Aleutian cackling geese (Branta hutchinsii leucopareia), which appear to be similar to hadedas in mass (geese: 1.55 kg; hadeda: 1.3 kg) and activity (Mini & Black, 2009). Our measure of caloric content of the hadedas prey is based on one species of earthworm, whereas in reality hadedas have a varied diet consisting of various invertebrates.…”

Foraging flight distances of wintering ducks and geese: a review

“…Although structurally different, the esophagus of geese is proportionally longer than that of dabbling ducks, so geese undergoing long foraging flights may be able to maintain their energy balance because they can return to the roost carrying substantial amounts of food (estimate of 100 ml in White-fronted Geese; Owen 1972). Additionally, geese spend longer amounts of time at the destination of their foraging flights, e.g., pastures, and longer amounts of time foraging in these sites (Davis et al 1989, Owen et al 1992, Mini and Black 2009) than dabbing ducks (Winner 1959, Jorde et al 1983. Moreover, geese often rest/loaf while in fields (Austin 1988, Davis et al 1989, Ely 1992, and these bouts of resting/loafing may allow for food temporally stored in the esophagus to pass into the hindgut before foraging continues Gauthier 1989, Fox et al 2008a).…”

Regional and intraseasonal variation in diet of wintering and staging Atlantic brant

“…Inger et al (2010) found that dietary constraints in wintering European light-bellied brent geese (Branta bernicla hrota) inhibited their reproduction in the subsequent breeding season. In general, range-wide spatial and temporal patterns in food use and resulting body condition of wintering birds reflect varying intraseasonal energy requirements and food resource availability (Hassall et al 2001, Mini and Black 2009, Ladin et al 2011. Additionally, the foraging behavior of wintering geese may change with resource availability and enable their use of new food sources (Kirby and Obrecht 1980, Black et al 2003, Jefferies and Drent 2006, Klaassen et al 2006.…”