Seasonal changes in the blood composition of captive and free-living White-crowned Sparrows

1979 ◽  
Vol 129 (2) ◽  
pp. 151-162 ◽  
Author(s):  
William A. deGraw ◽  
Michael D. Kern ◽  
James R. King
Keyword(s):  
Seasonal Changes ◽  
Blood Composition ◽  
Free Living

scholarly journals Basin-scale seasonal changes in marine free-living bacterioplankton community in the Ofunato Bay

Gene ◽  
2018 ◽  
Vol 665 ◽  
pp. 185-191 ◽  
Author(s):  
Md. Shaheed Reza ◽  
Atsushi Kobiyama ◽  
Yuichiro Yamada ◽  
Yuri Ikeda ◽  
Daisuke Ikeda ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Free Living ◽  
Bacterioplankton Community ◽  
Basin Scale

scholarly journals Coping with the extremes: stress physiology varies between winter and summer in breeding opportunists

2011 ◽  
Vol 8 (2) ◽  
pp. 312-315 ◽  
Author(s):  
Jamie M. Cornelius ◽  
Creagh W. Breuner ◽  
Thomas P. Hahn
Keyword(s):  
Environmental Conditions ◽  
Seasonal Changes ◽  
Strong Support ◽  
Stress Physiology ◽  
Harsh Environments ◽  
Lifetime Reproductive Success ◽  
Free Living ◽  
Trade Offs ◽  
Hormone Secretions ◽  
Red Crossbills

Seasonal changes in stress steroid hormone secretions are thought to reflect investment in self-maintenance versus reproduction. The capricious conditions hypothesis (CCH) posits that reduced corticosterone (CORT) secretion during stress coincident with parental phases of breeding is necessary in harsh environments because a full response would otherwise trigger repeated nest abandonments. To test this hypothesis, we measured seasonal changes in stress physiology in free-living red crossbills ( Loxia curvirostra ), an opportunistically breeding songbird that regularly breeds in summer and winter. This species allows unique comparisons of breeding physiology under very different seasonal environmental conditions within locations. We found strong support for the CCH: red crossbills showed reduced CORT secretion only when in high reproductive condition in the winter, when compared with summer breeders and winter non-breeders. These data demonstrate that behavioural status and local environmental conditions interact to affect mechanisms underlying investment trade-offs, presumably in a way that maximizes lifetime reproductive success.

scholarly journals Seasonal Changes of Blood Composition in Captive Bottlenose Dolphins

2002 ◽  
Vol 64 (11) ◽  
pp. 1075-1078 ◽  
Author(s):  
Fumio TERASAWA ◽  
Masakazu KITAMURA ◽  
Asami FUJIMOTO ◽  
Shin-ichi HAYAMA
Keyword(s):  
Seasonal Changes ◽  
Bottlenose Dolphins ◽  
Blood Composition

Photorefractoriness and seasonal changes in the brain in response to changes in day length in American goldfinches (Carduelis tristis)

2002 ◽  
Vol 80 (12) ◽  
pp. 2100-2107 ◽  
Author(s):  
Regan H Marsh ◽  
Scott A MacDougall-Shackleton ◽  
Thomas P Hahn
Keyword(s):  
Seasonal Changes ◽  
Late Summer ◽  
Day Length ◽  
Free Living ◽  
Strong Trend ◽  
Carduelis Tristis ◽  
Song Control System ◽  
Song Control ◽  
Seasonally Breeding ◽  
The Brain

We examined neural and gonadal responses to photoperiod in a late-summer-breeding finch, the American goldfinch (Carduelis tristis). First we measured seasonal changes in the gonads of free-living goldfinches. Next we determined whether the gonads of goldfinches held on constant long days would eventually regress spontaneously. Finally, we compared the hypothalamic gonadotropin-releasing hormone (GnRH) system and song-control system of breeding and postbreeding birds. The results confirm that the gonads of wild goldfinches regress in late summer and show that the gonads of goldfinches held on constant long days regress spontaneously. Thus, according to at least one criterion, goldfinches become photorefractory, like other seasonally breeding songbirds. As well, goldfinches exhibited similar seasonal changes in the brain to spring-breeding birds. There was a decrease in GnRH immunoreactivity in autumn and a strong trend towards a reduction in the size of song-control regions (although this was statistically significant for only one area). Thus, although goldfinches breed late in summer as day length declines, some of their physiological responses to changes in photoperiod are similar to those that occur in spring-breeding songbirds.

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