group of birds flying over treetops with sparse foliage against blue sky

animal avian bird birdwatching black blue conservation destination duck ecological ecosystem environment europe fauna feather flight flock fly formation fowl freedom goose group habitat high landscape majestic migration migratory nature ornithology outdoor protection reserve sail seabird silhouette sky small soaring sunlight travel travelling view waterbird waterfowl wild wildlife wing birds flying treetops sparse foliage maasvallei sunny autumn day meers elsloo netherlands