1. Department of Pharmacology and Therapeutics, College of Medicine, University of Cincinnati, Cincinnati, Ohio 45267

Abstract

THE spectacular hereditary trait of backward somersaulting by Tumbler pigeons has been known since 1600 AD¹ and was described by Darwin as "... one of the most remarkable inherited habits or instincts ever recorded ..."². The potentially important physiological mechanism of tumbling is unknown, largely because the extreme rapidity of the somersaulting blurs visual observation of the component motions^3–9. Filming at 2,000 frames per second the normal flight of Racing Homer pigeons and characteristic tumbling episodes by Parlor (non-flying) Tumbler pigeons, we observed the following. The body position of a pigeon just before and during tumbling is associated with abnormal dorsiflexion of the tail, which occurs within 15 ms after the pigeon is released. Tumbling is synchronised with apparently normal wing movements, propelling the pigeon in only a backward direction, at a rate of 8–10 somersaults per second.