The interaction of food availability and endogenous physiological cycles on the grazing ecology of red deer hinds (Cervus elaphus)

M.J. Heydon, A.M. Sibbald, J.A. Milne, B.R. Brinklow, A.S.I. Loudon

Research output: Contribution to journalArticlepeer-review


1. The objective of the study was to establish the role of endogenous circannual physiological cycles in regulating the grazing behaviour of red deer. 2. This was investigated by manipulating the timing of seasonal cycles in red deer hinds by administration of melatonin between July and October and comparing the subsequent grazing responses to either a low or high herbage biomass at the times of previously observed seasonal decline (autumn) and rise (spring) in voluntary food intake of enhoused animals. Food intake was determined using the n-alkane marker technique. 3. Melatonin treatment resulted in respective 15- and 10-day advances in the timing of the onset and termination of the breeding season of non-pregnant hinds, indicating a phase-shift in the underlying circannual rhythm of reproduction. 4. Melatonin also caused a significant depression in herbage intake by hinds grazing high herbage biomasses during autumn consistent with an advance in the timing of the seasonal appetite decline. Treatment did not affect the intake of hinds on the low biomasses in the autumn or animals on either pasture during spring. 5. The study demonstrates that endogenous seasonal appetite changes influence level of food intake in grazing deer, but the expression of these seasonal cycles is dependent upon food availability.
Original languageUndefined
Pages (from-to)216-222
Number of pages7
JournalFunctional Ecology
Issue number2
Publication statusPublished - 1993


  • Deer
  • Endogenous rhythm
  • Grazing
  • Melatonin
  • Red deer
  • Cervus elaphus

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