Plasticity of the Rufous-winged Sparrow, Aimophila carpalis, song control regions during the monsoon-associated summer breeding period.
Horm Behav
; 52(3): 401-8, 2007 Sep.
Article
in En
| MEDLINE
| ID: mdl-17673216
ABSTRACT
In most temperate zone songbirds, exposure to increasing photoperiod in the spring stimulates the reproductive system and induces reproductive behaviors. Additionally, the brain regions that control singing (song control regions; SCRs) are larger during the breeding season, thus paralleling changes in the activity of the reproductive system. However, in some birds, environmental factors other than photoperiod initiate breeding. For example, free-living male Rufous-winged Sparrows develop their testes in March due to increasing photoperiod, but have relatively low plasma T until after they begin to breed, usually in July, during the monsoon period when day length is declining. We tested the hypothesis that SCRs grow and singing behavior increases after the monsoon rains begin. We captured adult male Rufous-winged Sparrows in July 2002, 7 days before and 20 days after the monsoon rains began, euthanized birds in the field, collected their brains, and measured SCR volumes from sections immunostained for the neuronal marker NeuN. In June and July 2006, we measured song rates in the field before and after the monsoon rains. SCR volumes were larger and singing behavior increased after the onset of the monsoon rains, coinciding with the initiation of breeding. Unlike in other species studied so far, SCR volumes grew as day length was decreasing. Comparative studies utilizing species that do not breed when day length is increasing may provide information on the relative contributions of various environmental factors to SCR neuroplasticity.
Search on Google
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Reproduction
/
Seasons
/
Songbirds
/
Environment
/
High Vocal Center
/
Neuronal Plasticity
Type of study:
Risk_factors_studies
Limits:
Animals
Language:
En
Journal:
Horm Behav
Year:
2007
Document type:
Article
Affiliation country:
United States