Effect of artificial feeding on waterfowl in Lake Izunuma-Uchinuma

Abstract

Effects of artificial feeding on waterfowl were investigated at an artificial pond adjacent to Lake Izunuma-Uchinuma. We recorded the abundance of wintering waterfowl and the quantity of feed provided to the birds from November 2007 to March 2008. The most abundant species was Pintail Anas acuta, and the maximum abundance was 1,400 individuals on 10 January 2008. Second in abundance to Pintail was Whooper Swan Cygnus Cygnus, with a maximum of 110 on 23 January 2008. The number of Tufted Duck Aythya fuligula and Pochard A. ferina were less than that of Pintail and Whooper Swan, but those four species were the most common at the pond. The quantity of waterfowl feed (white rice, brown rice, etc.) increased between November and December and then decreased through March. Based on the Field Metabolic Rate (FMR) and body weight, the monthly energetic requirements were calculated for the four common species. Monthly energetic values of waterfowl feed were also estimated from the amount of feed, the caloric values of each food, and the assimilation efficiency. Percentage (feeding / FMR x 100) of energetic dependence by waterfowl on feed was 102 % in November and 94 % in March. However, the percentage was low (35-40 %) between January and February. This suggests that during the severe period of the wintering season (January-February), the energetic requirement of waterfowl largely exceeds the energy they gain from artificial feeding.