Sandgrouse as models of avian adaptations to deserts

Abstract

Sandgrouse have many adaptations whose cumulative effect is sufficient to let them thrive and reach high population densities. The adaptations include: (a) Selection of appropriate micro-environments: movement between sun and shade is reminiscent of heliothermic reptiles, conserving energy and water reserves; (b) Activity (flying and feeding) in the morning and evening, when metabolic heat can be dispersed most easily without invoking evaporative mechanisms; (c) Thermal insulation by feather erection and huddling with conspecifics at both low temperatures (energy conservation) and when ambient temperatures exceed body temperatures (water conservation); (d) Infrequent drinking (in some species at least), allowing exploitation of wider areas around watering points, and saving water and energy on drinking flights; (e) Reduced metabolic rate and selection of energy- and protein-rich seeds reduce food requirements, metabolic heat loads and possibly foraging time; (f) An excretory system apparently well adapted for water and salt conservation; (g) Specialized reproductive biology, reducing the metabolic demands for clutch formation and egg-water loss, and allowing the young to be watered without drawing on parental water reserves.