title: Physiological, Morphological and Behavioural Responses of Self-Feeding Precocial Chicks Copying with Contrasting Levels of Water Salinity during Development.
abstract: Combined physiological and behavioural responses to salt loads during development have rarely been studied in air-breathing vertebrates able to inhabit hypersaline habitats, but they may be of particular importance in understanding, for example, the differences among species in patterns of habitat use or ontogenetic diet switches. Here, we compared the physiological and behavioural responses of self-feeding precocial chicks developed in contrasting levels of water salinity. The model species was the Black-winged Stilt (Himantopus himantopus) a precocial shorebird that breeds in a range of habitats from freshwater to hypersaline wetlands. Specifically, we compared resting metabolic rate (RMR), heat shock proteins (Hsp70), plasma ions, hematocrit, body mass, body size, growth rate and head-shaking behaviour of captive-reared Black-winged Stilt fledglings developed under fresh (0 ‰), saline (20 ‰), and hypersaline (60 ‰) water. Contrary to expectations, none of the physiological and morphological variables measured differed significantly among treatments. Likewise, the RMR of wild and captive-reared fledglings was similar. Surprisingly, the saltgland mass of wild fledglings from freshwater and those from hypersaline habitats was also similar. However, head-shaking, a behavioural response associated to minimize salt intake and to expel the secretions of salt glands, differed according to salinity source: head-shaking rate increased with increasing salinity. The results of this study support the key role of behavioural osmoregulation in avoiding salt stress during development.
authors: MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal.
authors: Afonso R
authors: AR
authors: Rocha
authors: MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal.
authors: Rita
authors: R
authors: Silva
authors: Department de Anatomy, Cell Biology and Zoology, University of Extremadura, Avenida de Elvas s/n, 06071, Badajoz, Spain.
authors: Auxiliadora
authors: A
authors: Villegas
authors: Department de Anatomy, Cell Biology and Zoology, University of Extremadura, Avenida de Elvas s/n, 06071, Badajoz, Spain.
authors: Juan M
authors: JM
authors: Sánchez-Guzmán
authors: MARE-Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, 3000-456, Coimbra, Portugal.
authors: Jaime A
authors: JA
authors: Ramos
authors: Department de Anatomy, Cell Biology and Zoology, University of Extremadura, Avenida de Elvas s/n, 06071, Badajoz, Spain.
authors: José A
authors: JA
authors: Masero
mesh_terms: D000818:Animals; D001522:Behavior, Animal; D046091:Charadriiformes / Q000033:anatomy & histology / Q000502:physiology*; D017753:Ecosystem; D005618:Fresh Water / Q000737:chemistry*; D054712:Salinity; D053833:Wetlands