Ecology and Energetics of Sandlerlings Migrating to Four Latitudes

Abstract

We examined ecophysiological responses of Sanderlings (Calidris alba) to their nonbreeding environments in New Jersey (USA), Texas (USA), Punta Chame (Panama), and Puerto Viejo (Peru). Daily energy expenditure (DEE; measured using doubly labeled water) was strongly influenced by the thermal environment, being higher at colder locations, and equivalent to 4.2 times the basal metabolic rate of New Jersey, 2.8 in Texas, 2.1 in Panama, and 2.7 in Peru (200, 135, 100, and 129 KJ/d; n = 10, 5, 10, and 16, respectively. Time budgets varied among locations, but in all cases feeding and roosting accounted for °90% of daylight hours. Feeding times were 55% in New Jersey, 90% in Texas, 40% in Panama, and 45% in Peru, suggesting that Sanderlings required more time to satisfy their food requirements in Texas than in the other locations. Total body mass and body fat increased linearly with decreasing long—term mean January air temperature but, because of the synchronous increase in energy expenditure, predicted survival times during food deprivation increased only slightly. Individual Sanderlings experience different living conditions throughout their non—breeding distribution, with DEE and nutritional reserves being determined primarily by temperature. Time budgets vary accordingly to accommodate these demands.

Costs, benefits, and fitness consequences of different migratory strategies

“…In addition to regional differences in weather conditions, several of the estuaries in east England are large and open in structure, whereas the estuaries in south Ireland tend to be more enclosed and sheltered, which is likely to exacerbate differences in wind speed. Lower energy costs of living at more southerly latitudes has been described for other migratory species (Drent and Piersma 1990, Castro et al 1992, Wiersma and Piersma 1994 and, in some cases, this accords with individuals at southerly latitudes having lower basal metabolic rates (Kersten et al 1998). However, BMR is unlikely to vary considerably among temperate locations, and internal regulation of BMR would be likely to exacerbate the differences in energy balance between northern and southern locations, as a lower BMR would be expected for the warmer locations (Castro et al 1992, Kersten et al 1998.…”

“…For many migratory species, distribution ranges span large geographic areas, encompassing very different environmental conditions (Newton 2008). Large-scale variation in local weather conditions (Castro et al 1992, Ho¨tker 2002 and in the quality and quantity of food resources (van Gils et al 2005, Mathot et al 2007) can result in differing energy costs and benefits across the range (Quaintenne et al 2011). The conditions experienced during the winter season can also carry over into subsequent stages of the annual cycle (Gill et al 2001a, Norris et al 2004, Gunnarsson et al 2005a.…”

“…Migratory shorebirds typically winter along the coastal edges of continents over large latitudinal scales, across which individuals encounter very different environmental conditions (Castro et al 1992, Piersma et al 1993. Living costs are often lower for individuals wintering at lower latitudes, mostly as a consequence of local climatic conditions influencing thermoregulatory expenditure Piersma 1990, Castro et al 1992).…”

“…Living costs are often lower for individuals wintering at lower latitudes, mostly as a consequence of local climatic conditions influencing thermoregulatory expenditure Piersma 1990, Castro et al 1992). However, harsher weather conditions in northern wintering areas can be coupled with higher prey availability (van de Kam et al 2004, Mathot et al 2007), which can result in similar costs and benefits of occupying winter sites across a broad latitudinal range (e.g., Piersma et al 1991, Castro et al 1992). The population size, distribution, and range of migratory species can therefore be determined by the magnitude and direction of the trade-offs associated with each winter location, and their consequences for individual fitness (Newton 2004, Harrison et al 2011.…”

Consumption of benthic fauna by carnivorous birds in the Wadden Sea

“…The first three of the four mechanisms m e n t i o n e d are caused by the climatic conditions as determined by the geographical positions of the intertidal areas. The geographical position further influences the suitability for birds, as the climatic conditions influence their daily food requirements (Castro et al, 1992;Wiersma & Piersma, 1994). The consequences of these climatic influences are that the densities of most migratory shorebirds and the total consumption by birds are m u c h higher in southern areas (Zwarts, 1988;Hockey et al, 1992).…”