Figure - available from: Frontiers in Ecology and Evolution
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The location of the two field sites in Israel. The study was conducted at Lake Yeruham in 2017, and at Midreshet Ben-Gurion in 2018.
Source publication
Migratory birds are often not specifically adapted to arid conditions, yet several species travel across deserts during their journeys, and often have more or less short stopovers there. We investigated whether differences in thermoregulatory mechanisms, specifically evaporative cooling, explain the different behavior of three passerine species whi...
Citations
... Deserts and other xeric habitats are among the most challenging environments for maintaining organismal water balance (Paces et al., 2021;Cabello-Vergel et al., 2022). Despite the crucial importance of water to survival, how animals deal with water scarcity has received less attention than the consequences of reduced food availability (McKechnie et al., 2016;Cooper et al., 2019;Gerson et al., 2019;Paces et al., 2021;Cabello-Vergel et al., 2022). ...
... Deserts and other xeric habitats are among the most challenging environments for maintaining organismal water balance (Paces et al., 2021;Cabello-Vergel et al., 2022). Despite the crucial importance of water to survival, how animals deal with water scarcity has received less attention than the consequences of reduced food availability (McKechnie et al., 2016;Cooper et al., 2019;Gerson et al., 2019;Paces et al., 2021;Cabello-Vergel et al., 2022). An organism's water balance is a function of the interplay between (1) physical environment and water availability, (2) physiological and behavioral mechanisms for conserving water by reducing the total evaporative water loss (TEWL) and/or thermal conductance, and (3) the production of metabolic water (Bartholomew and Cade, 1963;MacMillen, 1990;Gerson and Guglielmo, 2011;Rutkowska et al., 2016;Albright et al., 2017). ...
Tracing how free-ranging organisms interact with their environment to maintain water balance is a difficult topic to study for logistical and methodological reasons. We use a novel combination of triple-oxygen stable isotope analyses of water extracted from plasma (δ¹⁶O, δ¹⁷O, δ¹⁸O) and bulk tissue carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes of feathers and blood to estimate the proportional contribution of marine resources, seawater, and metabolic water used by two species of unique songbirds (genus Cinclodes) to maintain their water balance in a seasonal coastal environment. We also assessed the physiological adjustments that these birds use to maintain their water balance. In agreement with previous work on these species, δ¹³C and δ¹⁵N data show that the coastal resident and invertivore C. nigrofumosus consumes a diet rich in marine resources, while the diet of migratory C. oustaleti shifts seasonally between marine (winter) to freshwater aquatic resources (summer). Triple-oxygen isotope analysis (Δ¹⁷O) of blood plasma, basal metabolic rate (BMR), and total evaporative water loss (TEWL) revealed that ~25% of the body water pool of both species originated from metabolic water, while the rest originated from a mix of seawater and fresh water. Δ¹⁷O measurements suggest that the contribution of metabolic water tends to increase in summer in C. nigrofumosus, which is coupled with a significant increase in BMR and TEWL. The two species had similar BMR and TEWL during the austral winter when they occur sympatrically in coastal environments. We also found a positive and significant association between the use of marine resources as measured by δ¹³C and δ¹⁵N values and the estimated δ¹⁸O values of ingested (pre-formed) water in both species, which indicates that Cinclodes do not directly drink seawater but rather passively ingest when consuming marine invertebrates. Finally, results obtained from physiological parameters and the isotope-based estimates of marine (food and water) resource use are consistent, supporting the use of the triple-oxygen isotopes to quantify the contribution of water sources to the total water balance of free-ranging birds.
