Horned “toads” are lizards, not amphibians. These unique reptiles, known for their flattened bodies and crown-like horns, are a distinctive part of the southwestern landscape. New Mexico is home to several species of these fascinating creatures. This article explores their biology, current status, and the challenges they encounter in the state.
Understanding New Mexico’s Horned Lizards
The common name “horned toad” refers to several species within the Phrynosoma genus, recognized by their broad, flat bodies and prominent head spines. In New Mexico, three primary species are found: the Texas Horned Lizard (Phrynosoma cornutum), the Roundtail Horned Lizard (Phrynosoma modestum), and the Short-horned Lizard (Phrynosoma hernandesi). These lizards exhibit excellent camouflage, blending seamlessly with their arid and semi-arid surroundings of sand, gravel, and sparse vegetation. Their diet primarily consists of harvester ants, which they consume in large quantities, often sitting patiently near ant trails to ambush their prey.
The Texas Horned Lizard prefers open areas with loose soil or sand, suitable for burrowing and egg-laying. It is identifiable by two prominent central head spines and dark stripes radiating from its eyes. The Roundtail Horned Lizard, a smaller species, often camouflages among rocky soils and pebbles in Chihuahuan desert and grassland communities. The Short-horned Lizard, more widely distributed, inhabits higher elevations, including shortgrass prairies and pine-juniper woodlands. Each species has adapted to specific microhabitats within New Mexico’s diverse terrain.
Current Conservation Status
The conservation status of horned lizards in New Mexico is complex, as their status varies by species and across state lines. While no horned lizard species is federally listed as “endangered,” state-level protections reflect significant population declines. In New Mexico, state law prohibits willfully killing, collecting, or transporting horned lizards, indicating a general protected status. This measure addresses historical illegal collection for the pet trade, as these lizards do not survive well in captivity.
The Texas Horned Lizard is listed as a “threatened” species in Texas and a “species of greatest conservation need” in Oklahoma due to population declines. Although its populations in New Mexico have not shown the same level of decline, they are still monitored and protected. The Greater Short-horned Lizard (Phrynosoma hernandesi) also receives threatened or special protections in New Mexico. The Roundtail Horned Lizard (Phrynosoma modestum) is globally listed as “Least Concern” by the IUCN, but its status can differ at more localized levels, such as being “Critically Imperiled” in Colorado, while being considered “Secure” in New Mexico. These varied classifications highlight that while some populations are stable, others face substantial challenges.
Threats to Horned Lizard Populations
Horned lizard populations face multiple threats that contribute to their decline in New Mexico. A primary concern is habitat loss and fragmentation, driven by urban development, agricultural expansion, and energy extraction. As natural landscapes are converted, the open, arid, and semi-arid grasslands and scrublands that these lizards require are diminished, isolating populations and limiting their movement. This loss of continuous habitat makes them more vulnerable to localized extinction events.
Pesticide use also poses a significant threat, primarily by impacting their main food source: harvester ants. Horned lizards are specialized predators, with harvester ants making up a substantial portion, sometimes up to 70-90%, of their diet. When pesticides are used to control ant colonies, whether directly or through herbicide use on native vegetation that ants feed on, it directly reduces the lizards’ food supply, leading to starvation and population declines. Invasive ant species, such as Argentine fire ants, further compound this issue by outcompeting native harvester ants, disrupting the food chain and offering a less nutritious alternative for the lizards. Lastly, illegal collection for the pet trade continues to impact wild populations, despite regulations against it.
How to Support Horned Lizard Conservation
Individuals can contribute to horned lizard conservation through several practical actions. Supporting efforts that focus on habitat preservation is beneficial, which involves protecting and maintaining the native arid and semi-arid environments where these lizards thrive. Landowners can encourage native grasses, which provide food for harvester ants, and consider controlled grazing practices that benefit the ecosystem. Creating natural corridors between properties can also allow lizards to move freely and access resources.
Avoiding the use of pesticides and herbicides in gardens and properties is another important step, as these chemicals directly harm harvester ant colonies, the lizards’ primary food source. Instead of chemical controls, alternative methods for pest management should be considered. Reporting any observed illegal collection or trade of horned lizards to wildlife authorities is also crucial, as these animals do not typically survive when removed from their natural habitat. Educating others about the importance of these unique reptiles and their ecological role can also raise awareness and foster a broader conservation ethic.