Effect of Nutritional Content on Artificially Supplied Seed Utilization of Wintering Birds in a Mixed Forest, South Korea

Abstract

This study was conducted to clarify the effect of nutritional content on artificially supplied seed utilization of wintering birds in a mixed forest in South Korea. The dominant tree species in this forest were Japanese red pine (Pinus densiflora), Mongolian oak (Quercus mongolica), Japanese emperor oak (Quercus dentate). At the study site, we selected 6 plots and set up 3 feeders in each plot. The feeders were located 1.5 m above the ground and spaced 1 m apart. We selected 3 types of food resources (kidney beans, brown soybeans, and peanuts) based on their energy per 100 g. We supplied 200 g of each food type at the feeders. Feeders were recorded with a digital camera (HDR AS15, Sony, Tokyo, Japan) for 2 h. This was conducted 3 times per day. The videos were then analyzed to determine the frequency of visits, duration of stay at the feeder, frequency of pecking on food items, and number of consumed food items. Moreover, social behaviors were analyzed. In this study, we used peanuts as high-fat food type. Peanuts were consumed at the highest frequency by marsh tits (Poecile palustris), great tits (Parus major), and Eurasian nuthatches (Sitta europaea). In addition, the type of food, temperature, and metabolic energy requirement affected food utilization in marsh tits and great tits. In our study, some evidence was found that wintering birds in temperate zones prefer high-energy food items. Limited food availability during winter affects social hierarchies.