Diurnal activity budgets of Mallard (Anas platyrhynchos) wintering at the Hattabara dam lake in Hiroshima prefecture, western Japan, were investigated during November 2000 to March 2001. Mallards spent 67.9, 16.0 and 14.7% of the time resting, preening, and locomoting, respectively. Less than 1% of the time was spent for each of feeding, alert, agonistic and courtship activities. Activity patterns varied among the months, apparently in response to declining water levels and human disturbances. Resting was the primary activity of Mallards throughout winter. Time spent on resting was highest (P< 0.05) during the mid day and evening, while the time spent on locomotion and courtship was highest during the morning (P< 0.05). Mallards used a site near the dam for resting during the day. The site was off limits to boaters and sport fisherman. During the night, they used the shallow areas for feeding because these areas were inaccessible during the daytime due to human disturbances. The shallow feeding areas dried up from December to January when water level decreased sharply. Mallards responded by leaving the dam lake at dusk to feed in the adjacent ponds during this period. More than 95% of the area of these ponds was covered by 2-3 m tall Common Reeds (Pharagmites australis) and was inaccessible to the Mallards. Appropriate management of the ponds may improve Hattabara dam lake as a waterfowl habitat.

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Nestling diet of Japanese Wagtails (Motacilla grandis) was investigated by the neck ligature method and compared with the food availability in their feeding habitat during the breeding season of 1999 in Higashi Hiroshima, western Japan . Nestling diet comprised of 85.5% insects, 14.2% arachnids and 0.3% chilopods in individual number basis. Odonata order comprised nearly one-fourth of the diet in dry weight basis. Diptera, Lepidoptera, Coleoptera, Orthoptera and Arachnida were also important contributors to the total prey weight. Chironomidae and Ephemeroptera families were the most numerous prey items but their contribution to the total prey weight was small. Electivity indices indicated that the Japanese Wagtail prefer certain prey items (Libellulidae, Tipulidae, Dytiscidae) when collecting prey for the nestlings.

ECEEcology and Civil Engineering ‰ž-p• ¶'Ô•HŠwAbstract:Wintering mandarin duck (Aix galericulata) populations and their behavioural adaptations were analyzed in relation to habitat conditions at six dam lakes in the Chugoku district of western Japan, from September 1999 to March 2000. Mandarin duck densities in the dam lakes were significantly correlated with the shoreline bordered by trees. Mandarin duck densities in the dam lakes were also affected by the decrease in the water level. Overhanging branches and dense vegetation along the shoreline provided mandarin ducks with suitable resting cover and shelter. Receding water levels made resting cover unavailable by exposing these sites. The most notable response to a decline in water level was to move into sites with abundant cover such as those found in pools of the inflow rivers. Since it is practically impossible to maintain constant water levels in dam lakes, we suggest that small adjacent impoundments with sufficient cover should be built to attract mandarin ducks to artificial reservoirs.