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On vision in birds: coordination of head-bobbing and gait stabilises vertical head position in quail.

Nyakatura JA, Andrada E - Front. Zool. (2014)

Bottom Line: We were interested in the biomechanics behind this phenomenon.Significant differences in the timing of head-bobbing were found between gaits.The timing of the head-bobbing behaviour naturally favoured by quail benefits vision during vaulting and bouncing gaits and potentially helps reducing the mechanical cost associated with head bobbing when using a bouncing gait.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität, Erbertstraße 1, 07743 Jena, Germany. john.nyakatura@uni-jena.de.

ABSTRACT

Introduction: Head-bobbing in birds is a conspicuous behaviour related to vision comprising a hold phase and a thrust phase. The timing of these phases has been shown in many birds, including quail, to be coordinated with footfall during locomotion. We were interested in the biomechanics behind this phenomenon. During terrestrial locomotion in birds, the trunk is subjected to gait-specific vertical oscillations. Without compensation, these vertical oscillations conflict with the demands of vision (i.e., a vertically stable head position). We tested the hypothesis that the coordination between head-bobbing and trunk movement is a means of reconciling the conflicting demands of vision and locomotion which should thus vary according to gait.

Results: Significant differences in the timing of head-bobbing were found between gaits. The thrust phase was initiated just prior to the double support phase in walking (vaulting) trials, whereas in running (bouncing) trials, thrust started around midstance. Altering the timing of head-trunk-coordination in simulations showed that the timing naturally favoured by birds minimizes the vertical displacement of the head. When using a bouncing gait the timing of head bobbing had a compensatory effect on the fluctuation of the potential energy of the bird's centre of mass.

Conclusion: The results are consistent with expectations based on the vertical trunk fluctuations observed in biomechanical models of vaulting and bouncing locomotion. The timing of the head-bobbing behaviour naturally favoured by quail benefits vision during vaulting and bouncing gaits and potentially helps reducing the mechanical cost associated with head bobbing when using a bouncing gait.

No MeSH data available.


Related in: MedlinePlus

Mean amplitude (± s.d.) ofEpandEkfluctuation (ΔEpandΔEk) in experimental trials (HB), simulated trials without head-bobbing (no HB) and simulated trials with inversely timed head-bobbing behavior (inv. HB). A: ΔEp in vaulting trials; B: ΔEp in bouncing trials; C: ΔEk in vaulting trials; D: ΔEk in bouncing trials.
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Figure 6: Mean amplitude (± s.d.) ofEpandEkfluctuation (ΔEpandΔEk) in experimental trials (HB), simulated trials without head-bobbing (no HB) and simulated trials with inversely timed head-bobbing behavior (inv. HB). A: ΔEp in vaulting trials; B: ΔEp in bouncing trials; C: ΔEk in vaulting trials; D: ΔEk in bouncing trials.

Mentions: Modified head-bobbing behaviour also influenced the amplitude of Ep and Ek fluctuations in the CoM. However, this influence is only reflected in effect size statistics and only for bouncing trials (Table 2; Figure 6A). In regard of Ep fluctuations, ANOVAs for both vaulting and bouncing trials were non-significant (p = 0.883 and p = 0.153, respectively). In experimental vaulting trials, fluctuations in Ep (0.007 ± 0.0044 J) did not differ significantly from simulated vaulting trials which did not feature head-bobbing (0.0074 ± 0.0044 J; p = 0.964) or from simulated trials in which the timing of head-bobbing was inversed (0.0078 ± 0.0045 J; p = 0.837) – as revealed by post hoc tests. Effect sizes were also minimal (Table 2).


On vision in birds: coordination of head-bobbing and gait stabilises vertical head position in quail.

Nyakatura JA, Andrada E - Front. Zool. (2014)

Mean amplitude (± s.d.) ofEpandEkfluctuation (ΔEpandΔEk) in experimental trials (HB), simulated trials without head-bobbing (no HB) and simulated trials with inversely timed head-bobbing behavior (inv. HB). A: ΔEp in vaulting trials; B: ΔEp in bouncing trials; C: ΔEk in vaulting trials; D: ΔEk in bouncing trials.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3987125&req=5

Figure 6: Mean amplitude (± s.d.) ofEpandEkfluctuation (ΔEpandΔEk) in experimental trials (HB), simulated trials without head-bobbing (no HB) and simulated trials with inversely timed head-bobbing behavior (inv. HB). A: ΔEp in vaulting trials; B: ΔEp in bouncing trials; C: ΔEk in vaulting trials; D: ΔEk in bouncing trials.
Mentions: Modified head-bobbing behaviour also influenced the amplitude of Ep and Ek fluctuations in the CoM. However, this influence is only reflected in effect size statistics and only for bouncing trials (Table 2; Figure 6A). In regard of Ep fluctuations, ANOVAs for both vaulting and bouncing trials were non-significant (p = 0.883 and p = 0.153, respectively). In experimental vaulting trials, fluctuations in Ep (0.007 ± 0.0044 J) did not differ significantly from simulated vaulting trials which did not feature head-bobbing (0.0074 ± 0.0044 J; p = 0.964) or from simulated trials in which the timing of head-bobbing was inversed (0.0078 ± 0.0045 J; p = 0.837) – as revealed by post hoc tests. Effect sizes were also minimal (Table 2).

Bottom Line: We were interested in the biomechanics behind this phenomenon.Significant differences in the timing of head-bobbing were found between gaits.The timing of the head-bobbing behaviour naturally favoured by quail benefits vision during vaulting and bouncing gaits and potentially helps reducing the mechanical cost associated with head bobbing when using a bouncing gait.

View Article: PubMed Central - HTML - PubMed

Affiliation: Institut für Spezielle Zoologie und Evolutionsbiologie mit Phyletischem Museum, Friedrich-Schiller-Universität, Erbertstraße 1, 07743 Jena, Germany. john.nyakatura@uni-jena.de.

ABSTRACT

Introduction: Head-bobbing in birds is a conspicuous behaviour related to vision comprising a hold phase and a thrust phase. The timing of these phases has been shown in many birds, including quail, to be coordinated with footfall during locomotion. We were interested in the biomechanics behind this phenomenon. During terrestrial locomotion in birds, the trunk is subjected to gait-specific vertical oscillations. Without compensation, these vertical oscillations conflict with the demands of vision (i.e., a vertically stable head position). We tested the hypothesis that the coordination between head-bobbing and trunk movement is a means of reconciling the conflicting demands of vision and locomotion which should thus vary according to gait.

Results: Significant differences in the timing of head-bobbing were found between gaits. The thrust phase was initiated just prior to the double support phase in walking (vaulting) trials, whereas in running (bouncing) trials, thrust started around midstance. Altering the timing of head-trunk-coordination in simulations showed that the timing naturally favoured by birds minimizes the vertical displacement of the head. When using a bouncing gait the timing of head bobbing had a compensatory effect on the fluctuation of the potential energy of the bird's centre of mass.

Conclusion: The results are consistent with expectations based on the vertical trunk fluctuations observed in biomechanical models of vaulting and bouncing locomotion. The timing of the head-bobbing behaviour naturally favoured by quail benefits vision during vaulting and bouncing gaits and potentially helps reducing the mechanical cost associated with head bobbing when using a bouncing gait.

No MeSH data available.


Related in: MedlinePlus