Master Naturalists: Texas spiny lizards give us a garden surprise
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Spring is a Texas spiny lizard's nesting time.
H.M. Smith's "Handbook of Lizards" describes Sceloporus olivaceus as a rusty, arboreal, diurnal, insectivorous iguanid." In scientific terminology, he described a rough-scaly, mottled-colored lizard living in trees, hunting both day and night and eating insects for food.
They are 8- to 11-inches long, including a 4- to 5-inch tail.
S. Olivaceus are common, preferring mesquite groves as habitat over grasslands. Smith and others say they're found from South Central Oklahoma, southward through the Texas prairie, to southeastern Coahuila and southern Tamaulipas in Mexico.
In our yard, we see them sunning on warm days, even in winter, but more from late February/early March to the end of October. Texas spiny lizards cannot be approached, they're shy/nervous. They are lightning-fast sprinters when disturbed in the open, racing up a tree or wall or diving into leaf litter or mulch in our flower beds.
They're not ground dwellers, but spiny lizards nest on the ground like most reptiles. Mated females select a spot with fairly dry, loose soil, good sun exposure and dig a slanted hole about 5- to 6-inches deep and about 4-inches wide.
Females back into their hole and deposit eight to 30 cylindrical, leathery eggs, one half of an inch long, and one fourth of an inch in diameter. After refilling the hole, hiding the eggs, they never return to the nest. The eggs will hatch in between 43 to 83 days.
Paul's garden surprise
Watching a mother lizard at work during her nesting period was new to Paul until last week. He was battling weeds in a bed next to the garage, a southwest exposure. It's a sunny area with good soil. Looking down, he saw her, two feet away, backing into her excavated nest in the flower bed. Though he was very close to her, she didn't run away. Remaining calm, she began laying eggs.
She appeared to be in a fugue or trance state similar to endangered Kemp's ridley sea turtle females when laying eggs on coastal beaches. As the associated pictures show, Paul could and did approach within six inches of the lizard.
After running into the house to get a camera, he took pictures of her, her clutch of eggs and her nest. He watched her about 15 minutes until she finished laying her eggs.
After resting, she crawled out of the nest and quickly pushed soil back into her excavation. Still ignoring Paul, she crawled slowly to the brick wall at the back of the bed and climbed about 6 to 7 feet and rested there for at least two hours. Because her tail's a bit short due to an injury, we recognize her when we see her.
Research by zoologists like Harold W. Kerster suggests we may see her again next year because spiny lizards have average life spans of at least a couple of seasons (20.6 months).
And, while they move about some, females generally do not move more than 30 meters from their nesting sites in a lifetime. Males have about twice that range.
Sources: "Neighborhood Size in the Rusty Lizard, Sceloporus olivaceus," Harold W. Kerster, Evolution, Vol. 18, No. 3 (Sep., 1964), pp. 445-457; Handbook of lizards: lizards of the United States and of Canada, H. M. Smith, Comstock Publishing Co, 1946; herpsoftexas.org, Herps of Texas, Texas Natural Science Center at The University of Texas at Austin
Paul and Mary Meredith are master naturalists. Contact them at firstname.lastname@example.org.