The ways that reptiles reproduce can be keys to species recognition, since there are some interesting variations that are worth looking at in more detail.
All reptiles reproduce sexually, as do every other member of the vertebrates. However, there are often courtship behaviors and rituals that are unique to the species. These behaviors can include changes in pigmentation and coloration, strutting, and head bobbing. It is common for males of most species to become much more aggressive than normal during mating season, particularly toward other males.
The choice of location for these displays may also be different from the places the animals normally are found. For instance, sage lizards are normally found on rocks or near sagebrush where they have a ready avenue of escape from predators.
However, during times of mating, these little lizards may be commonly seen in open areas, and since they tend to be less wary of danger, they are often more preyed upon during this period of time.
The mating rituals may be extended over weeks. They may just as easily be quite brief or non-existent, again depending on the species.
The mating also can seem bazaar. For instance, if you are in the woods of California or Oregon, you may be lucky enough to see what appears to be a large ball of writhing snakes. Closer inspection may reveal that there is 10 to 15 California Garter Snakes curled up into the ball. This is a mating ball. At the center is a female, and numerous males surround her. She may be mated by many of the males, though the whole mating process seldom lasts longer than an hour. The ball then disintegrates as the snakes unwrap and each goes its separate way.
There is also a great deal of variation in where each species of reptile chooses to nest. Abandoned burrows are a favorite location for many, while others may dig their own burrows. Some will nest in trees, others under rocks, and still others only near water.
Most reptile species are oviparous. That is, they lay eggs. The eggs are usually contained in a leathery membrane rather than a hard shell like those of birds. The majority of oviparous reptiles will lay their eggs in the chosen nest, and then will leave the developing eggs and subsequent young to fend for themselves. However, some remain near the eggs and serve an active role in protection.
Then, too, there is variation in how the eggs are laid. Many species will lay a large number of eggs in a single clutch, while others may lay only one or two eggs, but will do so in several different places.
Many other species of reptiles are ovoviviparous, however. Instead of laying the eggs, they are retained within the female's body until they are developed. This can give the impression that the young are live born, though they really aren't. An example of this sort of birthing is found in the Western Diamondback Rattlesnake.
As with the egg layers, the mother may remain for a time with the young and protect them, or she may immediately leave.
In virtually all cases, the young are able to fend for themselves from the very beginning, though protection from the mother may give them more of a chance at survival. This is especially important for those species that don't have large numbers of young each year.
Reptile reproduction can be quite interesting to observe if you are lucky enough to witness it. Some reptiles breed easily in captivity and others do not. This huge variation is one of the things that make reptiles so interesting.