The metabolic cost of walking on an incline in the Peacock (Pavo cristatus)

Abstract

Altering speed and moving on a gradient can affect an animal’s posture and gait, which in turn can change the energetic requirements of terrestrial locomotion. Here, the energetic and kinematic effects of locomoting on an incline were investigated in the Indian peacock, Pavo cristatus. The mass-specific metabolic rate of the Indian peacock was elevated on an incline, but this change was not dependent on the angle ascended and the cost of lifting remained similar between the two inclines (+5 and +7°). Interestingly, the Indian peacock had the highest efficiency when compared to any other previously studied avian biped, despite the presence of a large train. Duty factors were higher for birds moving on an incline, but there was no difference between +5 and +7°. Our results highlight the importance of investigating kinematic responses during energetic studies, as these may enable explanation of what is driving the underlying metabolic differences when moving on inclines. Further investigations are required to elucidate the underlying mechanical processes occurring during incline movement.

How conspicuous are peacock eyespots and other colorful feathers in the eyes of mammalian predators?

“…Adult peacocks are reported to have several effective anti-predator strategies, including running [135], flight [136], fighting with their sharp spurs [28], hiding in dense thickets [29,129,135], roosting in high trees chosen for their protection against predators at dusk [129,137], and using group vigilance along with alarm calling [138]. Consistent with this, three studies have shown that the peacock’s train does not significantly hinder locomotor performance during flight or walking; indeed, peacocks walking on a treadmill were efficient compared to other avian bipeds for which data exist and had a reduced metabolic cost during the breeding season when their trains were fully grown [136,139,140].…”

How conspicuous are peacock eyespots and other colorful feathers in the eyes of mammalian predators?

“…Adult peacocks are reported to have several effective anti-predator strategies, including running [135], flight [136], fighting with their sharp spurs [28], hiding in dense thickets [29,129,135], roosting in high trees chosen for their protection against predators at dusk [129,137], and using group vigilance along with alarm calling [138]. Consistent with this, three studies have shown that the peacock’s train does not significantly hinder locomotor performance during flight or walking; indeed, peacocks walking on a treadmill were efficient compared to other avian bipeds for which data exist and had a reduced metabolic cost during the breeding season when their trains were fully grown [136,139,140].…”

Terrestrial locomotion energy costs vary considerably between species: no evidence that this is explained by rate of leg force production or ecology

“…61 Hoyt 54 HumanHomo sapiens2.19–4.0230.09–46.410.25–0.3878.88–80.20−0.51Bransford and Howley 62 Hoyt 54 Rat-kangarooBettongia penicillata1.10–6.2081.80–114.390.05–0.100.9770.95Webster and Dawson 63 PeacockPavo cristatus0.5–1.019.15–16.610.49–0.794.581.43Wilkinson et al . 64 King penguinAptenodytes patagonicus0.08–0.5015.91–25.630.56–0.7911.5–11.6513.25Fahlman et al . 65 Present studySvalbard rock ptarmiganLagopus muta hyperborean0.22–0.7533.76–46.220.30–0.550.7329.3Lees et al .…”

How conspicuous are peacock eyespots and other colorful feathers in the eyes of mammalian predators?

“…Adult peacocks are reported to have several effective anti-predator strategies, including running [135], flight [136], fighting with their sharp spurs [28], hiding in dense thickets [29,129,135], roosting in high trees chosen for their protection against predators at dusk [129,137], and using group vigilance along with alarm calling [138]. Consistent with this, three studies have shown that the peacock’s train does not significantly hinder locomotor performance during flight or walking; indeed, peacocks walking on a treadmill were efficient compared to other avian bipeds for which data exist and had a reduced metabolic cost during the breeding season when their trains were fully grown [136,139,140].…”

Terrestrial locomotion energy costs vary considerably between species: no evidence that this is explained by rate of leg force production or ecology

“…61 Hoyt 54 HumanHomo sapiens2.19–4.0230.09–46.410.25–0.3878.88–80.20−0.51Bransford and Howley 62 Hoyt 54 Rat-kangarooBettongia penicillata1.10–6.2081.80–114.390.05–0.100.9770.95Webster and Dawson 63 PeacockPavo cristatus0.5–1.019.15–16.610.49–0.794.581.43Wilkinson et al . 64 King penguinAptenodytes patagonicus0.08–0.5015.91–25.630.56–0.7911.5–11.6513.25Fahlman et al . 65 Present studySvalbard rock ptarmiganLagopus muta hyperborean0.22–0.7533.76–46.220.30–0.550.7329.3Lees et al .…”

How conspicuous are peacock eyespots and other colorful feathers in the eyes of mammalian predators?

“…Adult peacocks are reported to have several effective anti-predator strategies, including running [135], flight [136], fighting with their sharp spurs [28], hiding in dense thickets [29,129,135], roosting in high trees chosen for their protection against predators at dusk [129,137], and using group vigilance along with alarm calling [138]. Consistent with this, three studies have shown that the peacock’s train does not significantly hinder locomotor performance during flight or walking; indeed, peacocks walking on a treadmill were efficient compared to other avian bipeds for which data exist and had a reduced metabolic cost during the breeding season when their trains were fully grown [136,139,140].…”

Terrestrial locomotion energy costs vary considerably between species: no evidence that this is explained by rate of leg force production or ecology

“…61 Hoyt 54 HumanHomo sapiens2.19–4.0230.09–46.410.25–0.3878.88–80.20−0.51Bransford and Howley 62 Hoyt 54 Rat-kangarooBettongia penicillata1.10–6.2081.80–114.390.05–0.100.9770.95Webster and Dawson 63 PeacockPavo cristatus0.5–1.019.15–16.610.49–0.794.581.43Wilkinson et al . 64 King penguinAptenodytes patagonicus0.08–0.5015.91–25.630.56–0.7911.5–11.6513.25Fahlman et al . 65 Present studySvalbard rock ptarmiganLagopus muta hyperborean0.22–0.7533.76–46.220.30–0.550.7329.3Lees et al .…”