The preserve is one of the last remnants of the Tamaulipan thorn forest, a dense mosaic of at least 1,200 plants, from poky shrubs to trees like mesquite, acacia, hackberry, ebony, and brasil.

He was just 15 when, in a bid to attract more avians, he began planting several hundred native seedlings beside his house to create a 2-acre thorn forest—a term he prefers over the more common ...