Mixed gaits in small avian terrestrial locomotion.
Scientists have historically categorized gaits discretely (e.g. regular gaits such as walking, running). However, previous results suggest that animals such as birds might mix or regularly or stochastically switch between gaits while maintaining a steady locomotor speed. Here, we combined a novel and completely automated large-scale study (over one million frames) on motions of the center of mass in several bird species (quail, oystercatcher, northern lapwing, pigeon, and avocet) with numerical simulations. The birds studied do not strictly prefer walking mechanics at lower speeds or running mechanics at higher speeds. Moreover, our results clearly display that the birds in our study employ mixed gaits (such as one step walking followed by one step using running mechanics) more often than walking and, surprisingly, maybe as often as grounded running. Using a bio-inspired model based on parameters obtained from real quails, we found two types of stable mixed gaits. In the first, both legs exhibit different gait mechanics, whereas in the second, legs gradually alternate from one gait mechanics into the other. Interestingly, mixed gaits parameters mostly overlap those of grounded running. Thus, perturbations or changes in the state induce a switch from grounded running to mixed gaits or vice versa.
Science of Motion, Friedrich-Schiller University of Jena, Germany.|Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller University of Jena, Germany.
Emanuel
E
Andrada
Computer Vision Group, Friedrich-Schiller University of Jena, Germany.
Daniel
D
Haase
Science of Motion, Friedrich-Schiller University of Jena, Germany.
Yefta
Y
Sutedja
Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller University of Jena, Germany.|AG Morphologie und Formengeschichte, Bild Wissen Gestaltung: ein interdisziplinäres Labor, Institut für Biologie, Humboldt University Berlin, Germany.
John A
JA
Nyakatura
Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller University of Jena, Germany.|College for Life Sciences, Wissenschaftskolleg zu Berlin, Berlin, Germany.
Brandon M
BM
Kilbourne
Computer Vision Group, Friedrich-Schiller University of Jena, Germany.
Joachim
J
Denzler
Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller University of Jena, Germany.
Martin S
MS
Fischer
Science of Motion, Friedrich-Schiller University of Jena, Germany.
Reinhard
R
Blickhan
D000222:Adaptation, Physiological / Q000502:physiology*; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D001717:Birds / Q000033:anatomy & histology / Q000502:physiology*; D003198:Computer Simulation; D005684:Gait / Q000502:physiology*; D008124:Locomotion / Q000502:physiology*; D008954:Models, Biological; D005082:Physical Exertion / Q000502:physiology; D051598:Whole Body Imaging / Q000379:methods