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ZUGUNRUHE ACTIVITY IN CASTRATED BRAMBLINGS FRINGILLA MONTIFRINGILLA
Author(s) -
Lofts B.,
Marshall A. J.
Publication year - 1961
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.1961.tb02432.x
Subject(s) - gonad , evening , biology , population , nocturnal , zoology , period (music) , development of the gonads , ecology , endocrinology , demography , physics , astronomy , sociology , acoustics
Summary 1. Zugunruhe, a condition of nocturnal activity in caged migratory birds that is generally held to be identical to premigratory restlessness in the wild, developed in the spring in captive castrated male Bramblings Fringilla montifringilla. 2. Zugunruhe occurred in intact control birds about a week before it was recorded in castrates. Intact birds became restless each evening earlier than did the castrates. 3. Nevertheless, the peaks of intensity in both castrate and intact birds occurred at the same time and coincided with the period during which the bulk of the wild population migrated to their northern breeding grounds. 4. In intact birds Zugunruhe occurred during the initial period of seasonal gonad modification. It waned by the time of sperm‐production when, under wild conditions, the birds would have completed their journey to their distant breeding grounds. 5. The data suggest that the seasonal phenomena of migratory unrest and gonad development occur independently of each other. The remote possibility that migration is influenced by extra‐testicular androgens is mentioned.