RIO GRANDE VALLEY, Texas (ValleyCentral) — It may not feel quite like it, but the seasons are shifting in South Texas.

As daylight decreases, primordial urges prevail, and the world’s smallest migratory bird is one of the first to divulge that fall is in the air.

Ruby-throated hummingbirds are some of the earliest to migrate southward, and their vanguard is already passing through the Rio Grande Valley.

Throughout the Valley, colorful songbirds are flitting through backyards, while overhead migrating flights of waterfowl are arriving.

As peak fall migration approaches, vast rivers of birds will pass through America’s most critical migratory corridor in southernmost Texas.

Each spring and fall, hundreds of millions of birds pass through the region, far surpassing any other migratory ro

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