I was leading a birding WINGS tour in northeastern Mexico when the participants and I found these two snakes escaping an army ant swarm at the roadside. The location was about 1 km above the town of Gómez Farías, Tamaulipas. The elevation there is about 1300 feet, and the habitat is humid tropical (semi)deciduous forest (dominated by bursera sp). I posted these photos to the Field Collecting Forum and got some great responses. But there still seems to be some uncertainty as to the identity of them, especially the pink one.
Many thanks for your help,
Rich Hoyer Tucson, Arizona Field Leader for WINGS, Inc. http://www.wingsbirds.com
First, here is a photo showing both snakes in my hand. Closer shots follow.