The Lower Rio Grande Valley is highly regarded among birders for its wealth of bird species – indeed, more than 500 species of bird have been documented in our four-county area (Starr, Hidalgo, Cameron, and Willacy).
In fact, if were considered a state, we’d be in the top seven most speciose in the entire country (eBird, 2017).
A couple reasons for this diversity are related to our location and the variety of habitats found in our region. Our southern location in the United States is a great boon for our bird diversity.
Roughly 190 miles to our south (as the bird flies) is the Tropic of Cancer, lying beyond – the tropics.
Many tropical species of bird reach the northernmost portions of their range here in the South Texas.
This proximity also increases the chances a tropical species, such as the Amazon Kingfisher (seen only three times in the United States, all in South Texas) may show up.
We also get a large number of migratory species that pass through or (in the case of winter residents) to the Valley. Some of these species will follow the Gulf Coast south to avoid crossing the Gulf of Mexico as they travel. These include various raptors, such as the Broad-winged Hawk and Mississippi Kite (both rely on the lifting power of thermals to migrate).
These, along with a variety of other species, are called circumgulf migrants. Even some species that cross the Gulf of Mexico (trans-gulf migrants) are seen with regularity during migration.
The variety of habitats in our local ecosystem also contributes greatly to our diversity.
Coastal flats to our east host a variety of shorebirds. Terns, such as the large, orange-billed Royal Tern and the petite Least Tern, nest in colonies on spoil islands and sandflats.
Large tidal flats off the Laguna Madre are important for many migrating and wintering plovers and sandpipers, while coastal wetlands support a wide variety of wading birds, rails, and wintering ducks.
Moving inland, freshwater sources (ponds, resacas, and the Rio Grande) are host to some of our South Texas specialty birds, like Least Grebe, Ringed Kingfisher, and Green Kingfisher.
Some of our rarest breeding birds are found predominantly in riparian woodlands along the Rio Grande, such as the elusive Muscovy Duck (not the domestic or feral ones we see around town) and Red-billed Pigeon.