NEW BRAUNFELS, Texas -- Frigid cold and rugged terrain have dimmed hopes dramatically for an 18-month-old child missing for two nights from his family's home in the Texas Hill Country.

A police spokesman says the search for Joshua Davis of New Braunfels was switched to a "recovery effort" Sunday morning. New Braunfels police Lt. Michael Penshorn says that means "cadaver dog" crews have been brought in to assist the efforts to find the child.

More than 100 police, fire and emergency officials, along with volunteers from San Antonio and Austin, had joined forces to search for Davis.

Since two nights of temperatures as low as 20 degrees have passed, "if he was exposed in the wooded area around his family's home, there's little chance that he could have survived those conditions," Penshorn said.

Penshorn says all signs suggest that the child wandered from the house Friday evening.