Second-year birds lag behind full adults in developing breeding plumage; they have a lower body mass and a slower weight increase than full adults, and perhaps the demands made on their energy reserves during the migration flight are the main reason of the delayed moult.
They have a lower body mass and a slower weight increase than full adults, and perhaps the demands made on their energy reserves during the migration flight are the main reason of the delayed moult. Second-year birds lag behind full adults in developing breeding plumage.
Second-year birds lag behind full adults in developing breeding plumage. They have a lower body mass and a slower weight increase than full adults, and perhaps the demands made on their energy reserves during the migration flight are the main reason of the delayed moult.
Second-year birds lag behind full adults in developing breeding plumage. They have a lower body mass and a slower weight increase than full adults, and perhaps the demands made on their energy reserves during the migration flight are the main reason of the delayed moult.