Document Detail

Dual entrainment by light and food in the Svalbard ptarmigan (Lagopus mutus hyperboreus).
MedLine Citation:
PMID:  9783230     Owner:  NLM     Status:  MEDLINE    
The possibility that feeding may act as a zeitgeber has been investigated in captive Svalbard ptarmigan by recording feeding or food-searching activity (FA) in birds given periodic access to food (PAF) under light-dark (LD) cycles or in continuous bright (LL) or dim light (DD) conditions. Except during LL, anticipatory attempts to feed always occurred prior to the food access interval with a relatively stable phase relationship to the interval. There was always a second bout of feeding toward the end of the food access interval, which apparently corresponds to the afternoon bout of feeding, seen under LD and ad libitum access to food. During PAF, this afternoon peak of activity disappeared. When the LD cycle was phase delayed while restricted access to food remained unchanged, the afternoon peak of feeding was temporarily reestablished but was transiently shifted forward to reattain its position within the food access interval. After termination of PAF, the afternoon bout of feeding was reestablished through phase-delaying transients, with an initial phase corresponding to the previous food access interval. The results suggest that FA of Svalbard ptarmigan is controlled by 2 separate circadian oscillators, both of which can be entrained by light and food: a putative morning oscillator, which controls the activity associated with the beginning of the photoperiod or the food access interval, and a putative evening oscillator, which induces increased activity toward the end of these intervals. In their natural environment at very high latitudes, Svalbard ptarmigan deposit fat when the day length declines rapidly in autumn. Entrained by feeding, they appear to enjoy a longer daily period of food-searching activity than if day length was the only zeitgeber.
E Reierth; K A Stokkan
Publication Detail:
Type:  Journal Article    
Journal Detail:
Title:  Journal of biological rhythms     Volume:  13     ISSN:  0748-7304     ISO Abbreviation:  J. Biol. Rhythms     Publication Date:  1998 Oct 
Date Detail:
Created Date:  1998-12-18     Completed Date:  1998-12-18     Revised Date:  2003-11-14    
Medline Journal Info:
Nlm Unique ID:  8700115     Medline TA:  J Biol Rhythms     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  393-402     Citation Subset:  IM    
Department of Arctic Biology, University of Tromsø, Norway.
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MeSH Terms
Animal Feed*
Biological Clocks / physiology*,  radiation effects*
Birds / physiology*
Food Deprivation / physiology

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