Journal of comparative physiology. A, Sensory, neural, and behavioral physiologyNov 1, 1994

Daily Body Temperature Rhythms in Japanese Quail and the Roles of Their Eyes and Pineal Gland

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Updated Apr 2, 2026

Abstract

Japanese quail maintain a circadian rhythm in body temperature that is significantly impacted by eye removal.

Quail exhibit a consistent daily cycle in body temperature that can be influenced by light-dark cycles.
Pinealectomy alone does not significantly alter the body temperature rhythm in quail under various lighting conditions.
Most quail retain their rhythmic temperature patterns after optic nerve section, though some show reduced robustness and 25% become arrhythmic.
Quail subjected to both pinealectomy and optic nerve section demonstrate similar rhythmic behavior to those with optic nerve section alone.
Complete eye removal results in all quail becoming arrhythmic in constant darkness, indicating the eyes play a crucial role in maintaining circadian rhythms.

Simplified

Japanese quail exhibit a robust circadian rhythm in body temperature. This rhythm is readily entrainable by 24 h light-dark (LD) cycles and persists under constant conditions. Because both the pineal organ and the eyes have been implicated as major components of the circadian system of birds, the role of these organs in generating the rhythm of body temperature was investigated. Pinealectomy, when performed alone, had little effect on the body temperature rhythm of quail either under LD or under constant darkness (DD). Most birds subjected to optic nerve section alone remained rhythmic in DD although the "robustness" of the rhythm was decreased, and 25% became arrhythmic. Birds subjected to both pinealectomy and optic nerve section behaved similarly to birds subjected to optic nerve section alone. However, complete eye removal, when performed alone or in combination with pinealectomy, caused all birds to become arrhythmic in DD. The data support the hypothesis that the eyes are the loci of circadian pacemakers in quail that act, via both neural and hormonal outputs, to preserve the integrity of (self-sustaining or damped) circadian oscillators located elsewhere.

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Daily Body Temperature Rhythms in Japanese Quail and the Roles of Their Eyes and Pineal Gland

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