Abstract: Migration stopover sites play a crucial role in providing the energy needed for long-distance journeys of migratory birds, and thus are essential for the smooth completion of the migration process. From January to February 2023, we recorded the daily behavior rhythms and behavior patterns of Ciconia boyciana at different habitats in Fushan Reservoir, Anhui Province, using instantaneous scanning and focal animal sampling methods. The daily maximum population recorded reached 505, representing more than 5% of the world population. During the stopover period, the main behaviors of Ciconia boyciana in Fushan Reservoir were foraging (53.29%±30.32%), resting (32.81%±26.68%), vigilance (10.45%±6.35%), and grooming (3.45%±2.95%). Foraging was the predominant behavior during the migration stopover period, with three peaks in a day: 07:40-08:40, 12:40-13:40, and 16:40-17:40. In the habitats of the open water surface and the mudflat, the time budget of foraging was the most, while in farmland, time allocation of resting was the highest. The average foraging duration was 86.48±112.70 s, with the highest pecking frequency (8.80±14.72 times) observed in mudflat habitat and the highest success rate of foraging (44.44%±52.71%) recorded in farmland. The average size of their food was 40.24 cm. Fishes were the dominant food types (97.30%), with most being dead (94.44%). On average, the processing time for food was 75.07 s. Food would be pecked or swallowed according to their sizes. The new discovery of migration stopover sites and the study of migration stopover behavior patterns in an artificial reservoir in the lower reaches of Huaihe River provide important information to enrich and improve the migration stopover network and behavioral ecology of Ciconia boyciana.

Key words: lower reaches of Huaihe River, reservoir, Ciconia boyciana, migratory stopover, behavior pattern