Associations among fluctuating asymmetry, tonic immobility duration, and flight distance or ease of capture in chickens.

The purpose of this study was to analyze the associations among fluctuating asymmetry, duration of tonic immobility, and flight performance or ease of capture in chickens. Cocks (n = 220; 36 wk old) from 10 Spanish breeds and a White Leghorn population were used. The quantitative/qualitative relationship among fluctuating asymmetry, duration of tonic immobility, and landing accuracy (good or bad) or landing distance (long or short), and the quantitative/quantitative relationship among fluctuating asymmetry, duration of tonic immobility, and time of capture or number of attempts of capture were studied. Relative fluctuating asymmetry of toe length, wing length, and the combined relative asymmetry of toe length, leg length, wing length, and leg width was significantly greater (P < 0.05, P < 0.01, and P < 0.001, respectively) in cocks with bad landing accuracy. There was no significant difference for the duration of tonic immobility between groups of cocks with bad or good landing accuracy. Relative asymmetry of wing length and the combined relative asymmetry of the 4 traits was significantly greater (P < 0.05) in cocks with short landing distance and smaller in cocks with long landing distance. There was a significant difference for the duration of tonic immobility between groups of cocks with short or long landing distance (P < 0.001), with that of cocks with short landing distance being longer. There was no significant correlation among relative fluctuating asymmetry, duration of tonic immobility, and time of capture or attempts of capture. Associations between morphological values of toe, leg, and wing and flight performance or ease of capture were not significant. Thus, birds with less asymmetry and fear level have better flight performance than more asymmetric and fearful birds, whereas the ease of capture is not associated with fearfulness and asymmetry.