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Body condition, territory ownership and age‐related reproductive performance in Spruce Grouse Dendragapus canadensis hens
Author(s) -
REYNOLDS JIM
Publication year - 1997
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.1997.tb04687.x
Subject(s) - biology , reproduction , avian clutch size , seasonal breeder , grouse , reproductive success , body weight , zoology , ecology , habitat , demography , population , endocrinology , sociology
Adult Spruce Grouse Dendragapus canadensis hens show better reproductive performance (i.e. larger clutch size, earlier clutch initiation, higher frequency of renesting) than year‐lings. Body and breast muscle weights, condition indices and relative body composition were compared between adult and yearling birds from northeastern Ontario, Canada, to determine whether differences in endogenous reserves mobilized for egg production and (or) territory ownership could explain these differences in reproductive performance. Adults and yearlings showed similar declines in body‐weight, breast muscle weight and condition indices from the pre‐laying to the post‐laying period, but no significant interage differences emerged at any stage of the breeding season. Changes in body composition, especially gut structure, were similar in all birds; this result is consistent with a dietary shift in both age classes from a fibrous winter diet to more succulent foods in spring. Non‐territory‐holding (replacement) yearlings also had similar body‐weights and breast muscle weights and were in similar condition to territory holders (residents) in the pre‐laying period. My findings do not support the hypothesis that differences in body condition and territory occupancy can account for differences in age‐related reproductive performance in Spruce Grouse.