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GROWTH AND DEVELOPMENT OF NESTLING HEN HARRIERS
Author(s) -
Scharf William C.,
Balfour Edward
Publication year - 1971
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.1971.tb05162.x
Subject(s) - hatching , biology , sexual dimorphism , zoology , growth curve (statistics) , feather , growth rate , brood , ecology , statistics , mathematics , geometry
SUMMARY Nestling Hen Harriers Circus cyaneus in Orkney were weighed and measured during two nesting seasons. The 501 weights and 390 longest primary measurements produce a composite record of growth for this species. The general shape of both weight and primary growth curves is sigmoid. The primary feather growth can be measured at age seven and eight days after hatching and is less variable as an index of growth than is weight. The nestling period varies usually from 30 to 36 days, and age at first flight depends on the ratio of primary length to weight. Males usually fly before their heavier female siblings. The asynchronous hatching produces a size‐rank between nestling Hen Harriers. The significance of the size‐rank to growth and mortality is discussed. Sexual dimorphism develops at the nestling stage. Weights and measurements of males and females at different ages are tabulated. Asynchronous hatching, and the influence of latitude differences on growth rate are briefly discussed.