Monday, April 22, 2013


Well, it's getting that time of year where all the animals are getting frisky. Many of the amphibians are waiting for their larvae to hatch, and some are in the race against time to metamorph for terrestrial life before their breeding pools dry up.

Now that it is getting warm enough for the reptiles to stir, their season of reptile love (and war) is starting to begin. In particular, I came upon a male Northern Fence Lizard (Sceloporus undulatus) trying to woo a female in courtship. Typically, fence lizards do push-ups to mark their territory and to signal that other lizards should stay away; however, in this case, there is a male and a female fence lizard present, so I am guessing it has more to do with that than anything else. For the fence lizards, mating season typically begins in April. On top of their macho push-up routine, males will also use a pheromone to attract a mate.

Maybe it is because I interrupted the process, but I don't think the female showed much interest. (For both videos, play in higher resolution).

Please forgive the disenchanting narration. My coworker called to tell me he
had found a snake.

In part to attract a female, but also to show how tough they are, males also have a bright blue coloration on their belly and neck. Thus, when the lizard conducts their push-up routine, the colors are flashed as the lizard goes up and down. One way to tell the difference between a male and female is that the blue color is much less intense on a female, and it often is less apparent on the neck. Below is the male, and from this angle you can see the blue much more vividly (The blue doesn't show up unless it is played on the higher resolution youtube setting).

If the mating is successful, the female will be in gestation for about eight weeks, after which she will lay the eggs under a few inches of soil. This will help regulate the temperature of the eggs. Depending on when the eggs are laid, they will hatch between June and September. The size of the female determines how many eggs are laid, and it ranges from 3-13 eggs per clutch. During the year, a mature female can have multiple clutches. Younger females (1 year-old), typically only have one clutch per year.

As these are a very common species, I'm sure you all have been seeing them moving about now that spring is here.

Adolph, S., W. Porter. 1996. Growth, Seasonality, and Lizard Life Histories: Age and Size at Maturity. Oikos, 77: 267-278.
Ferguson, G., C. Bohlen, P. Woolley. 1980. Sceloporus Undulatus: Comparative Life History and Regulation of a Kansas Population. Ecology, 61: 313-322.
Presidents and Fellows of Harvard College. 1983. Lizard Ecology. Cambridge, Massachusetts: Harvard University Press.

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