‘The Valley’ has many incredible birding hotspots: state, county, and city parks, and national wildlife refuges. It is a great place to see Mexican birds at the northern limit of their range.
Public camping options are limited however. Two county parks is about it. I stayed at Adolph Thomae Jr County Park, on the Arroyo Colorado near Laguna Madre.
I tallied 4 lifers on the trip, including a somewhat rare vagrant from Mexico, a female Crimson-collared Grosbeak, at Edinburg Scenic Wetlands & World Birding Center. The Elf Owl pair, seen at Bentsen-Rio Grande Valley State Park, is another bird that only ventures to the U.S. in extreme southern Texas, New Mexico, and Arizona.
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The City of Brownsville Landfill is a surprisingly great birding hotspot.