Foster and Kreitzman - Seasons of Life - Caged birds
Type of Spiritual Experience
Several experiments have already shown that system cues can be detected even when birds are caged.
Even birds placed in constant conditions of light and dark exhibit this behaviour. Overall birds kept in laboratory conditions exhibit identical behaviour to that they would undergo if they were not in a laboratory and therefore controlled environment.
A description of the experience
Seasons of Life – Russell G Foster and Leon Kreitzman
Caged migratory birds have a seemingly odd behaviour that has provided one of the keys to investigating migration.
Since the mid eighteenth century, bird fanciers have known that usually diurnal migratory birds show an overall increase in activity at night and excessive hopping at about the same time of year as non captives prepare for migration.
In the 1930s German ornithologists called this surrogate migratory behaviour Zugun ruhe. In 1949 Gustav Kramer used this observable and measurable restless behaviour as a marker for migratory activity when he demonstrated that red backed shrikes and black caps placed in cages under the night sky, often tended to orient themselves towards the side of the cage corresponding to the normal migration direction.
Birds kept in a constant laboratory environment for years still show an annual rhythm of migratory behaviour. Their off-spring, born and bred in these constant conditions, show the same timing capability. Similarly, groups of ground squirrels kept in constant light conditions but at different temperatures – some at near 0 degrees C and some at 22 degrees C still show hibernatory activity at about the same time of year.