‘Vital signs’

November 19, 2018

BROWNSVILLE — It may have once been a battlefield, but today the 3,400 acres of coastal prairie that make up the Palo Alto Battlefield National Historical Park are an oasis for native plants and wildlife.

This open prairie is transformed along the edges of the park into dense thickets of mesquite, acacia and thorny undergrowth. Although there is no permanent water on the site, the park is laced with a series of shallow resacas, which hold water sporadically.

Coyotes, jackrabbits and bobcats are inside the park, and javelina and nilgai antelope are common. The site is a fine birding area as well.

Yet without a permanent water supply, it is the reptiles which flourish — especially the threatened Texas tortoise.

“In the late ’90s the park service developed these inventory and monitoring networks for all the parks,” said Rolando Garza, archeologist and chief of resource management. “The idea is they want to check the vital signs of the ecosystems in the park.

“One reason is so we know the resources and two to check the health of the ecosystem,” he added. “That way if something starts going bad, you’re aware of it and maybe can start correcting it or you may find it’s just a natural trend.”

Garza said the park has taken a special interest in its population of Texas tortoises, and has tagged 278 individual tortoises with identifying marks in order to study their movement within the park.

“Amphibians and reptiles are usually good indicators, and we also do vegetation,” he said. “We started doing water quality but we don’t really have any permanent water here at Palo Alto so we stopped that.

“The Texas tortoises are kind of our premier monitoring, our most successful,” Garza added.

Newly hatched tortoises are susceptible to predation by raccoons and some bird species, although once they reach a larger size they are pretty much without natural enemies in South Texas.

Many adult tortoises are killed by mowing along highways, however.

Nilgai antelope are common sights just after dawn on the battlefield, although white-tailed deer are no longer seen at the park.

Garza, a Brownsville native, said years ago deer were established on the park site but are no longer present.


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