Saturday, March 10, 2012

Salamander Migration

The weather is getting warmer and rainy, and that means it's about time for salamanders to start migrating from the woods to breeding ponds.

The salamanders you will see in vernal ponds around Ithaca are in the family Ambystomatidae. The two likeliest species are spotted salamanders (Ambystoma maculatum) and Jefferson's salamanders (Ambystoma jeffersonianum), though just north of Ithaca is a hybrid zone between Jefferson's salamander and it's northerly relative the blue-spotted salamander (Ambystoma laterale). They are relatively large salamanders measuring 5-7 cm and sporting heavier bodies than many of our other local salamanders.

Spotted salamander, Ambystoma maculatum

They spend most of the year under debris or underground, but like most amphibians their life cycle is tied to the water. Unlike reptile eggs, amphibian eggs don't have a shell to protect them from desiccation, so females lay their eggs in small ponds or other moist locations. Spotted and Jefferson's salamander courtship and fertilization also take place in the water. 

In the early spring, warm rain signals to these salamanders that it is time to breed. Males and females migrate to their breeding ponds, where the males court the females using pheromones released from their cloacal glands. They may use their their tails to fan the pheromones towards the females underwater. When a female becomes interested, the male walks and she follows him. He deposits a gelatinous packet of sperm called a spermatophore onto the bottom of the pond, then she walks over it and picks it up with her cloaca. Fertilization is internal, as it is with all other salamanders except for Cryptobranchids such as hellbenders.

Ambystoma maculatum in shallow pond

Jefferson's salamanders generally come out earlier in the spring than spotted salamanders do, and have even been known to crawl over snow on their way to the pond.

Ambystoma jeffersonianum braving the snow to breed

Many years, tens or possibly even hundreds of salamanders will come to a pond during a single night in a phenomenon often called explosive breeding. It is a fantastic thing to see and it attracts many people. While going out to see the salamanders provides an exciting night and a good learning experience, we must take care that we do not negatively impact the salamanders and their habitat.

-If you drive to a pond, make sure to park your car far enough away that you do not run over any salamanders that may be crossing the road.

-Each person in your group should have a bright light to see the ground around them. Keep your eyes on the ground and walk slowly, taking care not to step on any animals.

-Salamanders, like all amphibians, have very delicate skin. They easily absorb anything in environment, so touching one when you have lotion, bug spray, or anything else on your hands can harm them very badly. In addition, their skin must stay moist at all times. It is best not to pick them up, but if you do, first get your hands wet with damp leaves or water from the pond (not tap water from a water bottle-it has chlorine that can hurt them).

Notice how he got his hands damp before holding the salamander.

While you are out at the pond, you may hear or see other breeding amphibians. Some that we have locally are spring peepers, pickerel frogs, and wood frogs.

Happy spring and please enjoy the amphibians responsibly!

Photos: Brian Sherman

 Post by Jessica Tingle

No comments:

Post a Comment