They come in the spring and bring the birds home
The Thunder Birds (Animikii) are the creatures that cause the sound of thunder when they flap their wings; lightning is caused when they blink their eyes. The slow, rolling thunder we hear during the coming of a storm is that of the old Thunder Birds flying very high in the sky. The sharper thunderclaps are made by the wings of the young Thunder Birds who flap fast and violently.
It is said that Thunder Birds are like a great Eagle or Hawk, with a curved beak and clawed feet. Like birds of prey, they kill snakes and were the creatures that fought the underwater panther (Mishipeshu) and other great snakes that used to plague the earth. The Thunder Bird motif figured prominently in almost all ceremonies and was the symbol that unified the Anishinaabe. The sweat lodge represented the overturned nest of the thunderbird, with the hot rocks symbolizing the eggs of the Thunder Bird. As well, the teaching in the lodge revolved around the purifying and strengthening power of the Thunder Bird. Both the Midéwiwin and Wabanowin paid homage to the Thunder Bird. Even the Sun Dance, learned after moving to the Great Plains, was linked to a person’s dream or vision of the Thunder Bird, and one the chief purposes of the ceremony was to communicate with the Thunder Birds to bring rain to cleanse the world
It is an old tradition to give Thunder Birds an offering of tobacco when they come, offering words and asking that the Thunder Birds go easy on the Anishinaabe when the storm comes.
The Thunder Birds are migratory and are only heard from late spring until early fall. It is they who lead the other birds during the spring and fall migrations, and the constellation Cygnus – viewed as a long-necked swan by the Greeks – signifies a giant Thunderbird when viewed the opposite direction as the Anishinaabe do. This constellation is visible in the northern hemisphere from early May until late October, peaking in the summer sky during June and July. It is visible in the north-eastern sky from around 9 pm each evening during this time and by 2 am is directly overhead, staying high in the sky until daybreak comes in spring and leaves in fall, just as the birds migrate to the north and leave to the south before winter sets in.