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Annual cycles in the African stonechat Saxicola torquata axillaris and their relationship to environmental factors
Author(s) -
Dittami J. P.,
Gwinner Eberhard
Publication year - 1985
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1985.tb04937.x
Subject(s) - biology , moulting , population , photoperiodism , ecology , reproduction , zoology , testosterone (patch) , seasonal breeder , luteinizing hormone , annual cycle , nest (protein structural motif) , hormone , endocrinology , demography , sociology , larva , biochemistry , horticulture
Seasonal changes in gonadal size, body weight, male song and the plasma titres of luteinizing hormone (LH), oestradiol and testosterone were investigated in a free‐living population of African stonechats, Suxicola torquata axillaris , on Menengai Crater, Nakuru, Kenya. These were compared with the occurrence of nesting and moult in the population and a number of seasonally changing environmental factors including photoperiod, insect abundance and rain. Annual cycles in these stonechats appears to be regulated by endogenous events which are responsive to environmental factors on a seasonal basis. The dry season may play an important rôle in the synchronization of the population by inhibiting nesting in birds otherwise capable of reproductive activity. Rain is postulated as a time‐giving cue for moult and gonadal regression. The possibility of photoperiodic changes at the equator acting as seasonal time‐giving cues remains open.