Kinematics and Center of Mass Mechanics During Terrestrial Locomotion in Northern Lapwings (Vanellus vanellus, Charadriiformes)

Abstract

Avian bipedalism is best studied in derived walking/running specialists. Here, we use kinematics and center of mass (CoM) mechanical energy patterns to investigate gait transitions of lapwings-migratory birds that forage on the ground, and therefore may need a trade-off between the functional demands of terrestrial locomotion and long distance flights. The animals ran on a treadmill while high-speed X-ray videos were recorded within the sustainable speed range. Instantaneous CoM mechanics were computed from integrating kinematics and body segment properties. Lapwings exhibit similar locomotor characteristics to specialized walking/running birds, but have less distinct gaits. At slow speeds no clear separation between vaulting (i.e., walking) and bouncing (i.e., running) energy patterns exists. Mechanical energy recovery of non-bouncing gaits correlates poorly with speed and suggests inefficient use of the inverted pendulum mechanism. Speed ranges of gaits overlap considerably, especially those of grounded running, a gait with CoM mechanics indicative of running but without an aerial phase, and aerial phase running, with no preferential gait at most speeds. Compliant limb morphology and grounded running in birds can be regarded as an evolutionary constraint, but lapwings effectively make use of advantages offered by this gait for a great fraction of their speed range. Thus, effective usage of grounded running during terrestrial locomotion is suggested generally to be a part of striding avian bipedalism-even in species not specialized in walking/running locomotion.

Adjustments of global and hindlimb local properties during the terrestrial locomotion of the common quail (Coturnix coturnix)

“…As previously observed, swing leg behavior is highly conserved during all gaits (e.g. Gatesy and Biewener, 1991;Nyakatura et al, 2012;Stoessel and Fischer, 2012), while the retraction of the stance leg (e.g. Gatesy and Biewener, 1991;Nyakatura et al, 2012;Stoessel and Fischer, 2012), and therefore the aperture angle Andrada et al, 2013), is adapted as speed increases.…”

“…Gatesy and Biewener, 1991;Nyakatura et al, 2012;Stoessel and Fischer, 2012), while the retraction of the stance leg (e.g. Gatesy and Biewener, 1991;Nyakatura et al, 2012;Stoessel and Fischer, 2012), and therefore the aperture angle Andrada et al, 2013), is adapted as speed increases. At the local level, practically all the spring-like work was found to occur in the ITJ, while the active knee flexion is more likely to help in the regulation of the leg retraction.…”

“…Moreover, it has been demonstrated that terrestrial locomotion in small birds rarely approaches the ideal cases of either in-phase or out-of-phase fluctuation of both energy forms (e.g. Hancock et al, 2007;Nyakatura et al, 2012) as proposed to define walking and running mechanics (e.g. Cavagna et al, 1977;Heglund et al, 1982;Blickhan and Full, 1992).…”

“…Previous studies have shown that these transitions are often accompanied by: (1) smooth variations of spatio-temporal parameters as the speed increases (e.g. Gatesy and Biewener, 1991;Abourachid and Renous, 2000); (2) gradually increasing leg joint amplitudes with increase of speed (Gatesy and Biewener, 1991;Abourachid and Renous, 2000;Nyakatura et al, 2012;Stoessel and Fischer, 2012) and (3) a gradual shift from vaulting mechanics towards bouncing mechanics of the center of mass (CoM) (Rubenson et al, 2004;Hancock et al, 2007;Nyakatura et al, 2012). Gait changes appear to not always be correlated to changes in the metabolic energy consumption, but specialized walking/running birds utilize specific gaits at given speeds on a treadmill in correlation to energetic minima (Rubenson et al, 2004;Nudds et al, 2011).…”

“…Joint angles undergo smaller flexions during walking as compared with running (e.g. Gatesy and Biewener, 1991;Abourachid et al, 2011;Nyakatura et al, 2012;Stoessel and Fischer, 2012). When switching from walking to grounded running, this is considered to be equivalent to a switch from stiff-legged vaulting to compliant bouncing.…”