Stable individual profiles of daily timing of migratory restlessness in European quail.

Temporal characteristics of migratory behavior in birds are usually studied at the species and population levels, and rarely at the individual level. Variations among species and populations of the seasonal onset of migratory behavior have been widely investigated, but very little is known about its daily organization or whether birds are conservative in their behavior. The determination of intra- and inter-individual variability is important for the study of genetic variations and can reveal the existence of different adaptation capacities within populations.

Daily laying time in free-living European starlings: solar noon, a potential synchronizer.

Reproduction is generally controlled by important temporal constraints involving complex adaptive mechanisms. Birds, in temperate zones, present marked breeding seasonality as well as marked daily organization of reproductive behavior, especially laying. Intra-specific variability and determinants of this pattern have been investigated mainly in domestic non-passerine birds.

Inter-individual variability during morning choruses in Japanese quail males (Coturnix coturnix japonica).

We compared the organization of dawn choruses in five groups of Japanese quail, Coturnix coturnix japonica, males (four groups of kin-related males and one group of unrelated males). We documented the structure of chorus groups: one male sang much more than the others during the dawn peak in four of the five groups, and this regardless of the number of males in the group. The dominant singers were then removed from two similar-sized groups, one of kin-related (K3) and the other of unrelated (NK) males.

Daily organization of laying in Japanese and European quail: effect of domestication.

In the present study, we aimed to examine the possible effects of domestication on the daily organization of laying in female quail. To achieve this we compared laying patterns in a laboratory strain of Japanese quail with those in European quail originating from a wild population. Under LD 14:10, the same specific laying window was observed, with ovipositions occurring mainly between 7 h and 15 h after lights on.

Effect of a cranium-directed daily illumination cycle on the laying rhythm in Japanese quail.

This study tests the effect on the laying rhythm of a light cycle reaching directly the encephala via a diode in Japanese quail maintained in constant darkness. In DD, all the birds expressed their free-running laying rhythm (period close to 25 h). When the diode is switched on 14 h per 24 h cycle, females showed the same organization as in LD with the same laying time.

Circadian rhythms of oviposition and feeding activity in Japanese quail: effects of cyclic administration of melatonin.

The aim of these experiments was to test the effect of a cyclic administration of melatonin, by mimicking the daily rhythm of hormone levels, on the circadian organization of two distinct functions in quail: oviposition and feeding activity. Laying and feeding rhythms under photoperiodic conditions and constant darkness (DD) were investigated. Under DD, where the two rhythms were free running, a daily rhythm of melatonin was administered.

Daily temporal organization of laying in Japanese quail: variability and heritability.

In birds, many behavioral and physiological processes that occur during reproduction show daily rhythms in response to environmental temporal constraints. In this study, the individual daily organization of laying and its genetic determinant in Japanese quail (Coturnix coturnix japonica) were analyzed. For this purpose, the oviposition time of 102 randomly chosen females, maintained in long-day photoperiodic conditions (LD 14 h:10 h) for 1 mon was observed and extreme phenotypes selected.

Cyclic melatonin synchronizes the circadian rhythm of feeding activity in Japanese quail, Coturnix c. japonica.

In Japanese quail, we can observe the circadian rhythm of feeding activity in constant conditions, especially in birds from selected lines. In order to try to test the importance of melatonin as hormonal output for the circadian system, we gave a 24-h period cycle of exogenous melatonin to some of these birds when they were free running. We used castrated males firstly in order to cancel the known effect of steroids on circadian organisation.