Monocular sleep in male domestic chicks.
Behavioural sleep during the first 2 weeks after hatching was studied in male chicks reared with an imprinting object (I-chicks) and in social isolation (NI-chicks). Time spent in sleeping with both eyes closed (binocular sleep) decreased gradually with age in both I-chicks and in NI-chicks whilst the number of episodes of binocular sleep decreased with age in NI-chicks but not in I-chicks. The pattern of monocular sleep (only one eye closed) of both I-chicks and NI-chicks showed no significant bias towards predominant left- or right-eye closure during the first week. During the second week, I-chicks showed a tendency towards more pronounced left-eye closure with a peak on day 10, whilst NI-chicks showed a tendency for more pronounced right-eye closure with peaks on days 9 and 11. In a different group of chicks, changing the colour of the imprinting object on day 8 produced a shift towards right-eye closure. In contrast, the removal of the imprinting object on day 8 did not cause any change in the pattern of monocular sleep. Differences with respect to sleeping patterns previously observed in females chicks are discussed.
Mascetti
Gian Gastone
GG
Dipartimento di Psicologia Generale, Università di Padova, Via Venezia 8, 35131 Padova, Italy. giangastone.mascetti@unipd.it
Bobbo
Daniela
D
Rugger
Marina
M
Vallortigara
Giorgio
G
D000367:Age Factors; D000818:Animals; D001245:Association Learning; D002645:Chickens; D003118:Color Perception; D007839:Functional Laterality; D007173:Imprinting, Psychological; D009769:Object Attachment; D012890:Sleep; D012934:Social Isolation; D015349:Vision, Monocular