TUCSON, AZ (Tucson News Now) - When do Gila monsters hatch in the wild? Well, scientists have been trying to find out for decades.
"It's always been a question; it's always something I have thought about, but there's no way I can go out and trench the whole desert," said Arizona State University Professor Dale DeNardo.
DeNardo said scientists know that the animals lay eggs in July and the babies emerge from the ground between May and August the following year, but no one knows when the eggs hatch.
"You could take a back hoe and trench the desert every day, all day for six months; you're not going to find any Gila Monsters," he said.
He said that's because the reptiles are masters at hiding their nests, so documenting them in the burrow is nearly impossible.
That is until a construction crew accidentally dug up a nest in the foothills.
In October 2016, Rodger Repp got a call from a friend who works in construction. His friend told him the crew had just found a Gila monster nest outside a foothills home.
"So immediately I go down in the trench," Repp said. "He's showing me where the Gila monsters were found and all of a sudden a little nose comes wiggling out and wiggles out a little further, and little trickling dirt starts coming down on either side of the head. It was really one of the biggest thrills ever."
Repp has been studying the Gila monster for 13 years.
"For me the biggest purpose for moving here was to see a Gila monster in the wild," he said.
Two of the lizards found on the site were walking around, and three others were still coming out of their eggs.
Repp started documenting the nest right away.
After dozens of pictures and video, Repp packed up the lizards and took them to Arizona State University's research lab, where they remain.
"What's exciting about (this)," DeNardo said, "is that not only did someone find a Gila Monster nest which is hard enough, but they found a hatching nest."
"This is evidence that they are hatching in the fall. They are just not coming up. They are staying in that nest, which is very unique. No lizard has been known to do it," he said.
DeNardo believes this new evidence suggests that Gila monsters are similar to turtles.
"They hatch early in the nest in the fall, but they don't emerge until later." he said. "This is the first lizard to be known to do this."
Repp said he thinks baby Gila monsters emerge from the burrow when they are able to eat, and that they are waiting until other lizard eggs are laid.
So back to that question, when do Gila monsters hatch? Well, it seems they hatch around Halloween.
DeNardo plans to publish an academic report of his findings. The paper should be available sometime this year.