— Sunny days bring out the lizards

Story and photos by Anita Westervelt, Texas Master Naturalist

One warm, sunny, winter day you see a lizard sitting on a post soaking up the sun and realize you haven’t seen many lizards lately. Well, they’re not gone, they’re likely just brumating.

Lizards are ectotherms, which means their body temperature is the same as the environment around them. Humans and other mammals are endotherms, their internal functions keep their bodies at a warm temperature regardless of the outside temperature.

Winter is cold, even here in the subtropics. For most lizards, temperatures below 50 degrees Fahrenheit are too cold for them. And, too, during winter, there are a lot less bugs, insects and spiders available — all of which constitute a lizard’s primary food supply. Instead of being active, lizards will seek hollowed out logs, piles of leaves, sticks and other debris or burrow into the ground in order to be warm. They then will enter a state of lessened activity called brumation.

The word comes from Latin, bruma, meaning winter solstice, or midwinter plus the suffix, ation, from hibernation. The word was proposed by American zoologist Wilbur W. Mayhew, in 1965, to indicate winter dormancy in ectothermic vertebrates that demonstrate physiological changes independent of body temperature.

Brumation, by definition, is a state of sluggishness, inactivity or torpor exhibited by reptiles, such as lizards and snakes, during winter or extended periods of low temperature — a cold-blooded version of slowing down. It is not a true hibernation which is when an animal’s body temperature drops, its heartbeat and breathing slow and for some, an animal will go into a deep sleep and not wake up until spring.

A state of torpor also involves a lower-than-normal body temperature, breathing rate, heart rate and metabolic rate; it is a state triggered by ambient temperature and food availability. It is a less lengthy state than hibernation, and an animal’s body temperature and metabolic rate are not as low as during hibernation. A mammal prepares for a winter hibernation by eating extra food to be stored as body fat; these reserves keep the animal alive until it awakens and begins again to forage for food.

Lizards don’t bulk up in advance; during the state of brumation, they require less food to stay alive.

Once temperatures rise, the Rio Grande Valley will come alive with lizards, geckos, anoles, skinks and whiptails as they become active, beneficial participants, helping to control the insect population in the gardens, fields and nature parks.

To make a garden lizard friendly:

• Eliminate the use of pesticides which can poison lizards and their food source.
• Provide places for lizards to hide, keep warm in winter and cool in summer by tossing a small log beneath shrubs.
• Leave leaf litter in secluded parts of the garden.

For the most part, these reptiles are harmless to humans; however, some of them are not opposed to biting the hand that tries to capture them. It’s always best to leave them alone and keep them in the garden where they can do the most good.

Helpful resources in writing this article were biodiversity.utexas.edu, merriam-webster.com, reptilesmagazine.com, lizardsandfriends.org. britannica.com, thoughtco.com.

– 30 –

Side bar

Lizards and friends
Story and photos by Anita Westervelt, Texas Master Naturalist.

Finding lizards, geckos, anoles, skinks and whiptails in the garden is a sign of a healthy habitat.

A few of those found in the Lower Rio Grande Valley are described below.

Texas spiny lizard is a tree-dweller favoring mesquite trees where its colors and scale patterns are camouflaged against the bark of the tree. An adult can be from seven to 11 inches in length. They have long toes with sharp claws suited for climbing trees, utility poles and walls. Active during the day, they feed on insects and other arthropods, like centipedes, millipedes, mites, ticks, mosquitoes, June bugs, grasshoppers, scorpions and stink bugs.

Texas horned lizard is often confused with the Texas spiny lizard, although it is smaller, only reaching to six inches in length; it has a distinctively triangular shaped head with horns. Its coloring resembles the ground in its geographic region; they are rare in the Lower Rio Grande Valley but not extinct. They do not climb trees; they run and forage for food on the ground and feed almost exclusively on harvester ants.

House geckos are introduced species; they prefer urban habitat with warm, humid climates. Mostly nocturnal, they can easily be seen climbing walls around houses with porch lights that have attracted insects. They are harmless to have in and around the home; they feed on cockroaches, termites, moths, flies and spiders.

• Common house gecko generally isthree to six inches in length and ranges from pale pink to light gray and may have darker patches of color.
• Mediterranean house gecko can grow to four to five inches in length, is gray or tan with pink or purple undertones, dark mottling and striped tail.

Green anoles are exceptionally entertaining. They can grow to seven inches in length, are active during the day and adept at climbing trees, shrubs, fences and walls. They are frequently seen basking in the sun, lurking on small tree branches, or stalking insects. They can leap after prey or away from danger. They feed on crickets, cockroaches, moths, beetles, flies and butterflies.

Skinks have a dark-colored body of shiny, minute scales, with a colored stripe or stripes that run the length of the body. They have short legs and virtually no neck. Most skinks are active during the day. They prefer living on the ground. Skinks eat snails, slugs, cockroaches, grasshoppers, caterpillars, crickets, termites and newborn mice.

Whiptail, such as the common spotted whiptail, prefers dry grassland and sandy soils with sparse vegetation. They are seven to nine inches long, tan or brown and have seven or eight white, yellow or green stripes lengthwise from neck to tail. Active in the daytime, they are constantly on the move, feeding on small beetles, ants, grasshoppers and other arthropods.

Helpful resources in writing this were biodiversity.utexas.edu, lizardsandfriends.org, sciencedirect.com, reptilefollower.com and petinsurance.com.

– 30 –