The Influence of Daylength on Reproductive Timing in the Red Crossbill
The Influence of Daylength on Reproductive Timing in the Red Crossbill
复制标题
日长对红交嘴雀繁殖时间的影响
DOI：
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发表时间：
1965
期刊：
影响因子：
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通讯作者：
W. Dawson
中科院分区：
文献类型：
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作者：
H. B. Tordoff;W. Dawson
Early studies of reproductive timing in birds led to generalizations overemphasizing the importance of daylength as a regulating factor. Daylength is certainly important in stimulating gonadal development in many insectivorous passerines of temperate latitudes, but other factors, such as rainfall or its consequences, appear to control time of breeding in some birds of desert and tropical regions (Keast and Marshall, 1954; Miller, 1959, 1961; Immelmann, 1963; Oksche et al., 1963). Moreover, the unpredictable occurrence of reproduction in the Red Crossbill (Loxia curvirostra) suggests the influence of nonphotoperiodic factors on this largely boreal species. The Red Crossbill probably has the most erratic breeding schedule of any North American bird. At various localities in its range, it has been found over a period of time breeding in every month of the year. The nomadic tendencies of this species make the situation even more unusual. A locality inhabited by breeding birds in one year may not be used for several years thereafter. These irregularities in timing and location of breeding suggest that reproduction in this species is not primarily dependent on daylength. The extent of this dependence is analyzed in this paper.
