MATING GAME HAS MANY RULES

by Whit Gibbons

November 6, 2016

One of the biggest and one of the smallest salamanders in the world have a feature in common. No one knows how they mate or exactly where and when they lay their eggs. The large one is the greater siren. The tiny one is Chamberlain’s dwarf salamander.

Salamanders as a group are seldom-seen yet fascinating amphibians that should be appreciated as an exceptional part of the southeastern fauna. Australia has an abundance of unusual animals, but no salamanders are found anywhere on the continent. Each time I catch a salamander, I feel a sense of intrigue, for I know it is holding ecological secrets.

One night at the edge of a swamp, I watched a greater siren as thick as a soft drink can and longer than a chair leg creep along the muddy bottom of a pool of water in search of I know not what. I watched from the bank for several minutes, following its sinuous movements with my flashlight. I assumed it was looking for food – a crawfish or freshwater clam – but my hope was that it would encounter another greater siren of the opposite sex.

Despite the immense size of this native salamander of the Southeast, few people ever see one in the wild, and no one has seen them mate. Consequently, ecologists know next to nothing about their breeding habits, other than that they lay their eggs in the water.

Adult Chamberlain dwarf salamanders are no larger than a wooden kitchen match. Despite their much smaller size, they are a bit easier to find--if you use the right technique in the right place. I’ve watched my grandsons capture a dozen or more in a few minutes by sorting through wet sphagnum moss in the swamp.

We always check the adults to see if they are females carrying eggs. If they are, I ponder when they were fertilized, where they will lay them and how long they will take to hatch. I don’t know the answers, but no one else does, either. I find satisfaction in knowing that the opportunity for biological discovery still awaits.

Understanding the mating systems and social structure of animals is an intriguing area of ecological and behavioral research. Mating among animals is by no means a random, haphazard process. Within each species, mating strategies and patterns – often highly complex and intricate – have been shaped and molded throughout the species’ evolutionary history. Each year, as our knowledge across the spectrum of species is increased, patterns begin to take shape.

Some species, like Canada geese, are generally monogamous, often remaining with the same mate for life. Male wild donkeys may keep a harem of females and physically prevent younger males from mating with them.

The timing of mating also varies among species. Most frogs breed at night. Most birds breed during the day. Zebras breed year round. Garter snakes mate in the spring. Canebrake rattlesnakes look for mates in the fall.

One challenge for ecologists is to collect information about when, where and how mating occurs, and then find out if and how parental care is expressed. Being an ecological voyeur trying to determine the social structure of animal populations and unravel the complexities and relationships among individuals can be gratifying. Each new discovery about the breeding pattern of one species helps develop our understanding of its ecology and may give us insight about how other species reproduce.

Every animal has a mating story. However, in spite of our having discovered enough about breeding systems to identify patterns and classify them into categories, the basic observations of individual behaviors and strategies remain to be discovered for most species. Without question, mating patterns exist of which we are still unaware. One day, when someone adds the greater siren and Chamberlain’s dwarf salamander reproductive stories to the list, we may discover that one of our native wetland species has a fascinating breeding story of its own.

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