How to stay cool in a hot desert--a lesson from the rock pigeon

This review presents an overview of the puzzle called "cutaneous water evaporation (CWE) cooling mechanism" in birds. Heat acclimation of the rock pigeon induces cellular modifications that affect the myocardium, cutaneous vasculature, and the epidermis, and hence enable the initiation of CWE. These cells are the targets for adrenergic signals that participate in the mechanism that controls the initiation and intensity of CWE. As a result the cardiac performance of the heat acclimated pigeon is intensified in response to adrenergic agents, and peripheral blood vessels and the epidermis both increase their permeability in response to heat stress. The CWE cooling mechanism is more economical in terms of water conservation, and provides more efficient protection to its owner, compared to the 'classic' respiratory cooling mechanism. Moreover, current data present the rock pigeon--a small diurnal homeotherm--as a classic model for a desert bird.