How salinity and temperature combine to affect physiological state and performance in red knots with contrasting non-breeding environments

Physiological, Morphological and Behavioural Responses of Self-Feeding Precocial Chicks Copying with Contrasting Levels of Water Salinity during Development

“…Maintaining and using large, active saltglands is assumed to impose significant energetic and physiological costs, and adult waterbirds adjust the mass of saltglands to changing osmoregulatory demands (reviewed by [5,18]). As noted earlier, a recent study by [17] found that BMR and daily energy consumption of adult Dunlins increased significantly between freshwater and seawater, suggesting that developing and maintaining active saltglands is energetically expensive.…”

“…A recent study showed that adult individuals of a shorebird species, the Dunlin ( Calidris alpina ) increased their BMR and daily energy consumption by 17% and 20%, respectively, between freshwater and saltwater [17]. This finding provided strong support that maintaining functional osmoregulatory machinery to excrete excess salt imposes significant energy costs, probably owing to the increased size and metabolic intensity of supraorbital saltglands [17,18], the key organ used by air-breathing animals such as many waterbirds, seabirds and some reptiles to ensure survival in saline environments [5]. It is believed that such costs are unequal in adults and chicks, but studies addressing this question are scarce (reviewed in [5]).…”

“…The size of bird saltglands is strongly influenced by salinity levels [16,18,20], so self-feeding chicks of shorebird species breeding across a gradient of environmental salinity could show differences in resting metabolic rate (RMR) related to salinity levels. Studies involving the basal metabolic response of animals during development in relation to environmental salinity will provide new insights into the potential energy costs of inhabiting saline habitats, and the relative flexibility of this physiological trait to deal with salinity.…”

“…We used the Black-winged Stilt ( Himantopus himantopus ) as a model species (here onwards, stilt), a precocial shorebird that inhabits a variety of habitats during breeding, ranging from inland freshwater, to brackish, saline and hypersaline wetlands [23,24] (Fig 1). This set of physiological variables were measured because they may reflect saline stress in birds [18]. In particular, we measured Hsp70, which is assumed to be the major family of heat shock proteins in vertebrates, and has been used as an index of a range of environmental stressors including salinity (see [17] and references therein).…”

Does saline water consumption affect feeding and fuel deposition rate of a staging, long‐distance migrating passerine?

“…Our conclusions may not necessarily apply to other species and may be limited to the specific ecological circumstances, specifically water scarcity, prevailing in the study area in autumn. In addition, higher temperatures than the rather moderate temperatures recorded during the course of the experiment may induce higher water loss, thus possibly modulating bird sensitivity to changing water salinity (Gutiérrez et al ). Knowledge from previous studies (Sapir et al ) suggests that not all bird species and not even all Sylvia warbler species are influenced by water availability to the same extent as the blackcap.…”