Abstract
I investigated the site fidelity of wintering Pintails Anas acuta at Shinobazu Pond in Ueno, downtown Tokyo, from November 1987 to April 1988. Pintails and other species of ducks were wintering in this site and have been fed by the Ueno Zoological Gardens since 1966. 68 male Pintails were given individual numeric codes by applying hair-dye to the white patch on the breast. The presence or absence of those individuals was recorded regularly throughout the winter. Use of the pond by marked individuals was not constant, with 6.7 of marked individuals being recorded on a daily basis during the fall when the duck population at the pond was increasing, and 9.1 being recorded daily during the sedentary period of mid-winter.
