Abstract
Alectoris chukar and Ammoperdix heyi are permanent residents of the Negev Desert and are sympatric over much of their ranges. Sand partridges (body mass 150-250g), however, inhabit only arid and very arid areas, whereas chukars (350-600g) are widely distributed and inhabit deserts only at the margins of their ranges. Both species showed adaptation in the form of low energy metabolism, which ranged from 43-81% of that expected for birds of similar body mass. During summer, sand partridges had lower energy expenditures (5.47kJ.g-0.61.d-1) and water influxes (72.3mL.kg-0.75.d-1) than did chukars (6.42kJ.g-0.61.d-1 and 93.5mL.kg-0.75.d-1, respectively), indicating more pronounced adjustments to arid conditions in the desert specialist. Both species obtained more than half of their water influx in summer by drinking. Summer diet was relatively dry, mainly seeds (80%) with some green vegetation (18%) and, in chukars, occasional arthropods. Winter rains induced germination and reduced availability of seeds. Chukars were unable to maintain energy balance in the face of low ambient temperatures and a diet (90% green vegetation) that contained much water but comparatively little energy, and they mobilized fat reserves to meet energy requirements. Most sand partridges left the study area after winter rain, apparently migrating to the lower elevation, warmer, and drier Arava. The adaptations to hot dry conditions possessed by sand partridges may be accompanied by constraints on their abilities to cope with cool, wet conditions, and this may restrict them to arid and very arid habitats.-from Authors
Original language | English |
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Pages (from-to) | 1029-1037 |
Number of pages | 9 |
Journal | Ecology |
Volume | 68 |
Issue number | 4 |
DOIs | |
State | Published - 1 Jan 1987 |
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics