Establishment of Circadian Rhythm Experiments using Bengalese Finches

Marked increases in sleep deprivation and circadian rhythm disruption adversely affect human health and the quality of life. In particular, the expansion of nighttime lighting associated with a 24-h society and digital technology has promoted late-night activity in mothers and children. Studies have examined the effects of circadian disruption on brain development in chickens, which are diurnal animals with genomic similarities to humans; however, adult chickens lack post-hatching parental care, which limits their utility in analyses of parent-offspring interactions. In this study, we investigated the potential use of Bengalese finches (Lonchura striata domestica) as model animals for circadian rhythm and physiological research. Given that the small size of Bengalese finches makes it difficult to implant nanotags directly, we developed and fitted specialized garments containing nanotags. After one week under experimental light cycle conditions, rectal temperature and weight were measured, and the activity recorded by the nanotags was analyzed. The nanotag garments did not impede Bengalese finch flight nor did they influence body temperature, weight, or whole-blood glucose levels. Finches housed under a 12-h:12-h light-dark cycle exhibited minimal activity during the dark phase and increased activity after the lights were turned on, reaching peak levels above 40 counts. In contrast, finches housed under constant 24-h light exhibited relatively continuous activity levels of 5-20 counts, with no distinct resting phase. The results demonstrate that locomotor activity rhythms in Bengalese finches are strongly regulated by environmental lighting conditions, and that nanotag placement using specialized garments enables non-invasive physiological and behavioral monitoring. Overall, our findings support the use of Bengalese finches as a practical and effective model for circadian rhythm research to facilitate studies on physiological regulation, development, and future investigations into parent-offspring interactions.