The most famous denizen of the Homewood Forest Preserve is the Spotted Salamander (Ambystoma maculatum). And “famous” is no exaggeration. The creature is so celebrated that over the years dozens of Birmingham’s citizens have braved winter rainstorms in the dark of night – sometimes at painfully early hours of the morning – and driven to the preserve to witness these salamanders during their yearly migration. Why do salamanders migrate? And why would people get so excited about this species?
To begin with, the Spotted Salamander really is a charismatic, good-lookin’ species. Layered upon a base color of shiny black are two rows of large, brilliant-yellow spots that reach from its head to nearly the tip of its tail. These fanciful colors are one reason why the species is so popular. In addition, its large size (up to 10 inches!), humble disposition, and big, friendly eyes certainly help win the species its fans.
The Spotted Salamander’s annual migration has also led to its fame. Most of the year, these amphibians spend their time deep below the leaf litter or within rotting logs. These are sheltered habitats where a salamander can keep its skin moist, hide from predators, and hunt small animals. But during the late winter, the salamanders will leave the safety and comfort of their burrows and scramble downhill to find a seasonal pond and other salamanders that are also itching to mate. Many of the salamanders will migrate during the same night, and the trigger for the migration is a warm, late-winter rain. On that cue, dozens of Spotted Salamanders launch their migration.
The salamanders head for low areas near the creek at the base of the mountain where rainwater collects and remains for a few months. These are called vernal pools or seasonal pools. They are very important reproductive habitats for amphibians of many species due to the absence of fish. Many fish species are voracious predators of amphibian eggs and larvae, but fish populations can’t persist in pools that dry up. Larger pools are better for the salamanders because they have a lower risk of drying up before the young salamanders mature. But if pools are too large, they won’t dry up at all, and fish can become established.
When the migrating salamanders reach the pools, males and females evaluate their mating options through courtship rituals. Females then lay fertilized eggs in large jelly-like masses. After a few days, the adults then migrate back uphill, though not all at the same time.
The egg masses absorb water and – quite amazingly – swell to sizes that are many times larger than the size of the mother. Over the next few weeks, the embryos will grow and develop the features needed for their aquatic stage. Because the eggs are translucent, you can see these remarkable changes with subsequent visits to the pool. After six to eight weeks, the young hatch and spend the next two to three months in an aquatic stage, during which they hunt small animals in the water and grow rapidly. At the end of this period, the young emerge from the water, absorb their external gills, and begin a migration uphill into the forest. Unlike the downhill migration of the adults, the uphill migration of the young is asynchronous (in other words, they don’t all migrate uphill at the same time).
There are two pools at the Homewood Forest Preserve that are used by the Spotted Salamanders. One is a smaller pool on the same side of the road as the preserve. While salamanders don’t have to cross the road to reach it, it is small enough that it runs dry during many years, and young salamanders die before morphing into their terrestrial form. The other pool is larger and deeper, but is on the other side of a road leading to Homewood High School. Salamanders trying to reach this pool run the risk of being crushed by cars. This is especially a problem when there is an evening event at the school that coincides with the migration. Another problem with this pool at the time of this writing (August 2014) is that, due to changes in the flooding pattern of Shades Creek, the pool sustains a fish population because it no longer is seasonally dry. For these reasons, some conservationists are concerned that the preserve’s population may be unable to survive over the long term unless conditions in these pools improve. But the preserve’s population does have two important things going for it: the preserve is legally protected from development, and it has a fan club!
Spotted Salamander fans in the Birmingham area will sacrifice their sleep and brave several hours in the rain to both witness and protect the salamander migration. Different people will take turns checking the road and watching for signs of a migration. If a migration starts, a network of volunteers and enthusiasts is alerted, and fans converge on the preserve for a few hours of wildlife conservation and camaraderie. The few drivers on the road are asked to pause while volunteers clear the road of any salamanders or other migrating critters. These efforts help ensure that the preserve’s population continues to breed. The City of Homewood has supported their efforts by establishing an official salamander crossing zone on the street.
Getting up at odd hours of the night and standing in the rain in hopes of spotting (ha ha!) a salamander walking by is not an activity that the average citizen is adventurous enough to do. So, instead of bringing the people to the salamanders, salamander fans bring the salamanders to the people. In 2004, the Friends of Shades Creek began sponsoring the annual Salamander Festival in Homewood in hopes of promoting awareness about the plight of salamanders and the importance of conservation. There are children’s activities, music, dancing, crafts, delicious treats, and – of course – salamanders. A few sample salamanders of various sorts are on display, and some are even available for the curious to hold and examine up close.
Other known populations of Spotted Salamanders in the Greater Birmingham Metropolitan area live at Ruffner Mountain Nature Preserve and Oak Mountain State Park. But due to development of the landscape to suit the desires of humans, such healthy forests are increasingly rare in today’s world, and vernal pools are even rarer. Thus, if we are going to keep spotting the Spotted Salamander in our town, we need to continue these efforts to protect it.
–R. Scot Duncan