Yarrow’s spiny lizard (Sceloporus jarrovii)

Yarrow’s spiny lizard, scientifically known as Sceloporus jarrovii, is a medium-sized reptile species belonging to the family Phrynosomatidae. It is also commonly referred to as the mountain spiny lizard. This lizard is endemic to the southwestern United States and northern Mexico, specifically inhabiting mountainous regions.

Yarrow’s spiny lizard has a robust and compact body, typically measuring around 5 to 7 inches (13 to 18 centimeters) in total length, with a long and slender tail that is often longer than its body. Its body is covered in rough, keeled scales that give it a spiky or spiny appearance. The dorsal surface of the lizard is usually brown, gray, or olive in color, often with a pattern of darker spots or bands. The ventral surface is lighter in color.

This species is well-adapted to its mountainous habitat, where it can be found in rocky slopes, canyons, and forests at higher elevations. The mountain spiny lizard is diurnal, being active during the day when temperatures are favorable. It is an agile climber, often seen basking on rocks or perching on branches to regulate its body temperature.

Yarrow’s spiny lizards are insectivorous, with their diet primarily consisting of small invertebrates such as insects, spiders, and other arthropods. They are skilled hunters, using their excellent eyesight and quick reflexes to locate and capture their prey. They may also consume plant material on occasion, particularly fruits or flowers.

Breeding in Yarrow’s spiny lizards typically occurs in the spring and early summer. Males engage in territorial displays to attract females, which may involve head bobbing, push-ups, and color changes. What sets this lizard apart from others is its unique reproductive strategy known as ovoviviparity, which plays a significant role in its life history. Instead of laying eggs externally, the female keeps the eggs within her reproductive tract. The eggs are encased in a thin, permeable membrane that allows them to receive oxygen and nutrients from the mother's blood supply.  

When the embryos have reached a sufficient level of development and are ready to hatch, the female gives birth to live offspring. This process is often referred to as "giving birth to eggs" because the young lizards emerge from the egg membranes that have surrounded them throughout their development. This live birth method ensures that the hatchlings are better equipped to survive in their environment compared to being born as completely helpless neonates.  

Once born, the hatchlings are relatively independent compared to those of species that undergo live birth (viviparity). They have developed within their protective egg membranes, allowing them to have functional limbs, scales, and a better chance at survival in their mountainous habitat. They instinctively begin hunting for insects and seeking shelter to avoid predators.  

While not currently listed as a species of conservation concern, Yarrow’s spiny lizard may face threats from habitat loss or degradation due to human activities. Preserving their natural habitats and raising awareness about the importance of biodiversity conservation can help ensure the continued survival of this fascinating reptile species.

Overall, Yarrow’spiny lizard, with its spiky appearance, adaptation to mountainous environments, and interesting behaviors, remains an intriguing and charismatic reptile species within its range.