Iguanas are found in Arizona, but their presence in the state is varied. Some iguana species are native to Arizona’s desert landscapes, having adapted over time to the arid conditions. Other iguana species are considered non-native, having been introduced to the region through human activity. This distinction between naturally occurring and introduced populations is important for understanding their roles within Arizona’s diverse ecosystems.
Iguanas Native to Arizona
Arizona is home to at least one native iguana species, the Desert Iguana (Dipsosaurus dorsalis). This medium-sized lizard is well-adapted to the extreme heat of the Sonoran and Mojave deserts, which cover much of southwestern and far western Arizona. Desert iguanas reach lengths of up to 16 inches, including their long tails. Their coloration is a pale gray or whitish, adorned with a tan or brown reticulated pattern across their backs and sides. A distinguishing feature is a row of slightly enlarged, keeled scales running down the center of their backs.
These heat-tolerant reptiles are primarily herbivorous, feeding on leaves, flowers, and fruits, with a particular fondness for the yellow flowers of the creosote bush. They are active during the day, even in the hottest parts of summer when other lizards seek shelter, and can tolerate temperatures up to 115°F (46°C). Desert iguanas burrow in sandy areas, frequently at the base of creosote bushes, to escape extreme temperatures or predators. They also use burrows created by other animals, such as kit foxes and desert tortoises.
Non-Native Iguanas in Arizona
Beyond the native Desert Iguana, Arizona has experienced the introduction of non-native iguana species, primarily through the pet trade. Green Iguanas (Iguana iguana) are a prominent example, appear in residential areas due to accidental escapes or intentional releases by owners. These large, bright green lizards are native to tropical regions of Central and South America, requiring humid environments unlike Arizona’s dry climate. When introduced, they seek out areas with more moisture and vegetation, such as urban parks, irrigated communities, and riparian zones.
Another group of non-native iguanas sighted in Arizona are various spiny-tailed iguanas (Ctenosaura species). These lizards have a more robust build, with gray to brown coloration and distinctive spiny tails. Similar to Green Iguanas, spiny-tailed iguanas are escapees from captivity.
Distinguishing Native from Non-Native Species
Identifying Arizona’s native Desert Iguana from non-native species like the Green Iguana involves observing several key physical characteristics. The Desert Iguana is a relatively small lizard, under 16 inches in total length, with a pale gray to tan body and a reticulated pattern that blends with sandy environments. It possesses a small, blunt head and a single row of slightly enlarged scales along its spine.
In contrast, Green Iguanas are much larger, exceeding five feet in length, with a prominent dewlap under their chin and a crest of spines running down their back. Their coloration is bright green, though it can vary. Spiny-tailed iguanas, while also larger than Desert Iguanas, are characterized by their gray to brown bodies and, as their name suggests, noticeably spiny tails. These visual differences in size, color, and specific anatomical features are important for distinguishing between native and introduced iguana populations in Arizona.
Ecological Impact of Non-Native Iguanas
The presence of non-native iguanas in Arizona can lead to various ecological challenges. Green Iguanas, with their large size and adaptable diets, can compete with native wildlife for food resources, including vegetation and insects. Their herbivorous nature can also lead to damage to native plant communities, landscaping, and agricultural crops.
Beyond resource competition, non-native iguanas can also impact native animal populations. While primarily herbivorous, they are opportunistic feeders and may prey on smaller native lizards, insects, and bird eggs. Their burrowing habits can undermine infrastructure, such such as sidewalks, foundations, and irrigation systems. The introduction of these species can disrupt the balance of Arizona’s desert ecosystems, posing a threat to biodiversity and ecosystem health.
Reporting and Management of Non-Native Iguanas
If a non-native iguana is sighted in Arizona, it is important to report the observation to the appropriate authorities. The Arizona Game and Fish Department (AZGFD) is the primary agency responsible for managing wildlife, including introduced species. Reporting sightings is important for monitoring the spread of non-native populations and implementing effective control measures. Individuals should avoid approaching or attempting to capture these animals, as they can bite or scratch, especially when feeling threatened.
Instead, detailed information about the sighting, including location, date, and any distinguishing features of the iguana, should be provided to the AZGFD. This information assists wildlife managers in understanding the extent of non-native iguana presence and developing strategies to prevent further establishment or mitigate their impacts. Management efforts focus on preventing new introductions, removing established individuals, and educating the public about the risks associated with releasing non-native pets into the wild.