The great blue heron is a very large bird, the biggest heron in North America. We seem to come across the odd solitary bird fairly frequently when in Houston, in typical expectant pose waiting for signs of fish. These examples were in Archbishop Joseph A Fiorenza Park and beneath the bridge taking the I10 freeway over Buffalo Bayou. Amazing that this bird happily fishes while hundreds of cars and lorries thunder overhead.
The Audubon site gives good information on the vulnerability of this and other birds to climate change. Assuming that food sources hold up, they should still be around Houston for future generations.