Issue 10, 2019

Development of vernal migration in redheaded buntings: concurrent behavioral, physiological and neural changes under stimulatory photoperiods

Abstract

We investigated changes in behavior, physiology and selected brain regions during the development of vernal migration and reproduction phenotypes in migratory redheaded buntings. We monitored 24 h activity–rest pattern and measured food intake, fat deposition, and body mass of buntings exposed for 12 weeks to short (SP, 8L : 16D) and long (LP, 13L : 11D) photoperiods at 22 ± 2 °C temperature. Under LP, not SP, buntings exhibited a photostimulated spring migration phenotype (hyperphagia, fat deposition and body mass gain). However, there were sex differences in the development of vernal migration, as shown by faster and earlier induction of Zugunruhe (nocturnal migratory restlessness) in males than in females. In the next experiment, increasing photoperiods over 12 weeks following the vernal equinox induced behavioural and physiological changes associated with vernal migration phenotypes in both male and female buntings, but in a sex-dependent manner. In a subsequent experiment over 8 weeks corresponding to the spring migration period we found an increased expression of CART, not NPY, in INc, and decreased expression of GnRH-I in POA in the brain by week 6 of the observation under increasing photoperiods. There was also an increased expression of doublecortin (a marker of neuronal incorporation) in the olfactory bulb and song control nuclei (Area X and HVC, higher vocal centre) in male birds. These results demonstrate changes in the brain peptides and neuronal recruitment along with changes in the behaviour and physiology, and give insights into the concurrent photoperiodic induction of the seasonal response at multiple levels in migratory songbirds.

Graphical abstract: Development of vernal migration in redheaded buntings: concurrent behavioral, physiological and neural changes under stimulatory photoperiods

Supplementary files

Article information

Article type
Paper
Submitted
19 Jun 2019
Accepted
06 Aug 2019
First published
07 Aug 2019

Photochem. Photobiol. Sci., 2019,18, 2509-2520

Development of vernal migration in redheaded buntings: concurrent behavioral, physiological and neural changes under stimulatory photoperiods

N. Agarwal, R. Komal, Y. Kumari, S. Malik, S. Rani and V. Kumar, Photochem. Photobiol. Sci., 2019, 18, 2509 DOI: 10.1039/C9PP00273A

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