Geographical and temporal variation in environmental conditions affects nestling growth but not immune function in a year-round breeding equatorial lark.

Background: Variation in growth and immune function within and among populations is often associated with specific environmental conditions. We compared growth and immune function in nestlings of year-round breeding equatorial Redcapped Lark from South Kinangop, North Kinangop and Kedong (Kenya), three locations that are geographically close but climatically distinct. In addition, we studied growth and immune function of lark nestlings as a function of yearround variation in breeding intensity and rain within one location.