Twitterpated

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.

References

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.

Birds and the Bees, Sallies and the Streams

Well, not streams per se. But, with it being the season of pollen, green-up, and breeding comes the great breeding migration of the Spotted Salamander (Ambystoma maculatum) and the hatching of the Marble Salamander (Ambystoma opacum). Since the winter was so warm, breeding came early. In February, larvae of both species were swimming around in the vernal pools of Piedmont.

 A Spotted Salamander egg mass floating and hidden among vegetation.

The Marbled and Spotted Salamander have larvae that are deposited as eggs into vernal pools throughout the Southeast,  parts of the Midwest, and parts of New England. The Spotted Salamander's distribution also reaches into areas of Canada (Conant & Collins, 1998). Vernal pools, sometimes called ephemeral ponds, are seasonal wetland depressions found in woodlands. They fill during the winter and spring, and they dry during the summer and fall. Because they dry out, no fish can inhabit them--perfect breeding grounds for amphibians.

In the Piedmont of North Carolina, the hatching of the eggs for both species occurs simultaneously, and it can be difficult to distinguish between the two larvae. However, the Marbled Salamander larvae have black pigment on their throats and are typically larger (Mitchell & Gibbons, 2010). Both species have bushy external gills, tails for swimming, and two well developed forelimbs. Hind limbs develop during the larvae stage.

 Two Marbled Salamander larvae. 

Notice the tiny hind limbs and external gills.

The fascinating thing about these two species is not their aquatic larvae. Instead, it is the amazing journey the adults undergo in order to mate every year to two years. Both species are the only salamanders to mate on land. Marbled Salamanders migrate after mating occurs in October or November, and they lay their eggs in the dried ephemeral ponds. The eggs will only hatch after being inundated (Petranka, 1998).

 A Salamander larvae in its natural habitat, 

unaware of the looming net about to scoop it up!

Even more dramatic than that, Spotted Salamanders will migrate to breeding grounds during moist nights in late winter and early spring and will lay their eggs in flooded pools. It is unknown as to how salamanders orient themselves directionally, but they can travel great distances (200m-500m) to meet for the mating season (Petranka, 1998). For something only 22cm, that is a long way to go! Imagine having to go 900 to 2250 times our body size to find a mate.

 An adult Spotted Salamander. Found under a log

next to the vernal pool.

Unfortunately, given the migration patterns of the salamanders, there are great concerns for the survival and conservation of the two species. Besides the loss of ephemeral pools, habitat fragmentation by roads has isolated adult habitats from breeding grounds. With the small size and slow movement of salamanders, it is easy for them to be killed by motorists.

Hopefully you will have the chance to see one of these fantastic creatures! The best part is that they can be as far away as your backyard or local park.

Works Cited

Conant, R. and J.T. Collins. 1998. Reptiles and Amphibians of Eastern/Central North America. Houghton Mifflin Company, Boston, MA.

Mitchell, J.M. and W. Gibbons. 2010. Salamanders of the Southeast. University of Georgia Press, Athens, GA.

Petranka, J.W. 1998. Salamanders of the United States and Canada. Smithsonian Institution Press, Washington D.C.