HARLINGEN, Texas (KVEO) — Lurking in the murky canals and resacas of the Rio Grande Valley, the largest reptile in North America stealthily prowls in search of prey.

Chomping on an occasional fish, turtle, bird, or unwary mammal, American alligators ply the interconnected waterways of the lower RGV.

Capable of reaching some 15 feet in length and weighing more than 1,000 pounds these enormous predators can move surprisingly fast when snatching prey.

Nobody knows just how many of the toothy gators inhabit the RGV, but there is a thriving population at Laguna Atascosa National Wildlife Refuge east of Rio Hondo and on adjoining ranches.

In early morning and late afternoon the imposing reptiles can be seen basking on the banks, and some exceed 10 feet.

And this time of year you may encounter an amorous bull gator out for a stroll or bellowing to proclaim his territory and attract a mate.

Alligators and their predecessors have been roaming the earth for some 200 million years, but it is a matter of conjecture as to how long they have been residing in southernmost Texas.

An 1898 volume of the U.S. National Museum states alligators occur as far south as the Rio Grande. However, others believe the Nueces River was historically their southernmost home, and the Rio Grande Valley’s gator population is a result of escaped or released pets.

Whatever their origins, the RGV has harbored a relatively small population of alligators along the coast at least since the 1970’s. Periodic surveys on refuge lands have yielded as many a 110, but their numbers fluctuate depending on drought.

They do occasionally appear in the bay and Arroyo Colorado. Since the lower Valley’s system of resacas and canals are all interconnected, it is best to be on the lookout for the big reptiles.