Acoustic sensor arrays are recognized as an important development for field studies of animal behavior and ecology. While birds live in a 3D world and all dimensions seem important for most birds, use of these arrays has been limited almost entirely to 2D. A notable exception was the development by S. Asgari of Approximate Maximum Likelihood methods for 3D, tested with recorded sounds. Here we describe experiments with a time-of-arrival method for 3D localization of calls from Shrike-tanagers and Wood Wrens in a Mexican rain forest, using an acoustic sensor array we have used in past. Sub-meter accuracy was obtained in all of the x, y, z directions. It appears that the acoustic sensor arrays may prove very helpful for studying the behavior of birds in 3D.