Physiological Responses Of Birds To Flight And Running

Abstract

Summary 1. The energy required for sustained physical activity in flying and running birds is obtained from fatty acids mobilized from adipose stores under the influence of hormones. There is some evidence that glucagon, insulin and growth hormone may be involved in this process. 2. Energy expenditure can increase up to 14 times and 12 times resting values in flying and running birds, respectively. Energy expenditure varies only slightly over the normal range of flight speeds in individual species, but in running birds there is a linear correlation between oxygen consumption and speed. The slope of this relationship is an inverse function of body weight and indicates the energy cost of transport in ml O2.kg‐1.m‐1. 3. Increased oxygen demands by the working muscles are met by increased ventilation and circulation. Increased oxygen delivery by the blood is achieved by rises in cardiac output and oxygen extraction. Cardiac stroke volume changes relatively little and the increased cardiac output results mainly from an increase in heart rate. Regional blood distribution during exercise may be determined not only by the demands of the locomotory muscles but also by the need to increase heat loss from the skin and respiratory tract. 4. Ventilatory movements during flight are frequently synchronized in a I:I fashion with wing movements. Increased ventilation during flight and running may be stimulated, not only by the need for increased gas exchange, but also in order to raise heat loss by respiratory evaporation. Thermal hyperventilation carries a risk of CO, washout from the lungs and consequent blood alkalosis. The risk is minimized in some species by appropriate alterations in the rate and depth of breathing, which help to confine excess ventilation to the respiratory dead space. 5. Metabolic heat produced during exercise is either lost from the respiratory linings and the skin, or stored by the body with a resultant rise in body temperature. Changes in peripheral blood perfusion and active regulation of the feathers may assist cutaneous heat loss. Respiratory evaporation usually accounts for less than 30% of the total heat loss, even at high air temperatures, and becomes progressively less efficient at higher exercise intensities. At high air temperatures and high exercise intensities, most of the metabolic heat is stored, and exercise duration is limited as the body temperature approaches the upper lethal limit.

Quantitative comparisons of lung structure of adult domestic fowl and red jungle fowl, with reference to broiler ascites

“…After further similar experiments on six female domestic fowl in breeding condition raised on free range (Brackenbury et al, 1981), concluded that "hens are only just capable of running, or are extremely unwilling to run at faster speeds". The aerobic capacity of the males would be just sufficient to sustain level flight in a bird of the same body weight (Brackenbury, 1984), but these were "highly trained" birds; moreover this would leave nothing in reserve for take-off and climbing (Brackenbury and Avery, 1980). The impression that emerges is that the modern domestic fowl is not an athletic animal.…”

Avian Adjustments to Cold

“…3.1, 3.2). In contrast to the factors listed in Thble 1, the factorial scopes for activity metabolism can, as noted previously, reach 14 (flight) and 12 (running), though these values often lie between 5 and 10 (Brackenbury 1984). This comparison is complicated by several factors.…”

Aerobic capacity in wild satin bowerbirds: repeatability and effects of age, sex and condition

“…That scaling coefficient is indistinguishable from the interspecific scaling to mass 0.804 for flight V O2,max and mass 0.783 for flight wheel V O2,max found by McKechnie and Swanson (McKechnie and Swanson, 2010). Despite the similarity, we caution that the correlation between V O2,max and body mass in satin bowerbirds, although significant, explained relatively little of the variance in V O2,max , even after accounting for differences among sex and age classes (Figs2, 3) (Tucker, 1970;Brackenbury, 1984;Wiersma et al, 2007;McKechnie and Swanson, 2010). To our knowledge the BMR of satin bowerbirds has not been measured, so we used an allometrically derived BMR (McKechnie and Wolf, 2004 Numerous studies have explored possible relationships of body condition, morphological asymmetry and parasite infestations with ecology, behavior or whole-organism physiology in a variety of taxa (e.g.…”