I went there about a year ago. Awesome place isn't it? I took pictures to ask around but of course left them at the hotel anytime I went somewhere remote.
If you want help looking for them, I would take a day trip to La Restinga. It's a protected park consisting of mostly saltwater mangrove forests. The tours are conducted by old-timers on boat that are very much like the ones at Disney's jungle boat cruises. Most of the old boat captains have spent their entire lives on the island. If anyone would know, I think they would. There is also a nature center somewhere though I'm not sure exactly where it is.
The reported cribo came from the west side of the island where the climate is very dry. It looks very much like south Texas. La Restinga is located at the point of the island where the west and east ends are connected by a very small spit of land. I think asking those boat captains and any ranchers on the west side would be the key. There are also some freshwater marshes near Juan Griego that looked like couperi habitat. Good luck.
If you make it out to Los Roques you'll be amazed by the large number of lizards on the islands. They're some species of teid and they're EVERYWHERE.
Have fun, and be sure to report back.
Matt Kot
