I think the words spring and reproduction should be synonymous. Or at least in the natural world they should be. After all it is spring time when the plants, birds, animals and even the reptiles and amphibians all reproduce. All you need to do is spend five minutes outside at this time of year and you would know what I mean. Reproduction is happening all over the natural world.

The other day I put on my hip boots and headed out into a small shallow pond. On my way into the pond I observed a male and female Wood Duck. The male Wood Duck was displaying for the female. He would swim in front of the female and make a “zipping” call while showing off his brilliant breeding plumage. Reproduction is under way here.

Near the edge of the pond was a female Canada Goose sitting on her nest made of dried grasses with the inner cup lined with her own feathers. A set of six eggs lay nestled underneath her. The male was standing guard nearby and started honking very loudly when I got too near. Another pair of Canada Geese was swimming in the pond with five tiny yellow goslings swimming very close by their sides. Reproduction is complete here.

But none of this is what drew me to this pond on this wonderful spring morning. No it was the incessant calling of the male American Toad (Bufo americanus). For days this pond has been devoid of any toad or frog calls. I have been waiting for the toads to start breeding. In fact I have been keeping track of the dates when the toads start to call in this pond for several years and this year they are nearly 2 weeks later than usual.

When the water warms to the optimal breeding temperature the male toads enter the pond, swim to the center and crawl up onto any stick or branch that is sticking out of the water and get ready to call. They take a series of shallow breaths. You can actually see them hyper-inflating their lungs with each breath then a small patch of skin on their throat inflates. This is called the vocal sac, and they start to call.

The inflated vocal sac acts like a resonating chamber much like a drum. Here is how it works. The sound originates in their larynx or voice box. The toad takes air into it’s lungs and closes off its nostrils. The air is then forced up and out. The air rushing past the larynx produces the high pitched sound. The inflated air sac acts as a resonating chamber intensifying the sound carrying the call of the male toad far and wide across the pond.

The females who are listening for the males enter the pond and start to swim towards the calling males. This is all the males need to be enticed, because as soon as he sees a female drawing near he jumps from his calling perch and swims directly towards her.

The male grapples with the female until he has maneuvered himself on top of her. In most species the female toad is much larger than the male. He grasps her just behind her front legs and won’t let go. When the two toads are locked together this is called amplexus. Floating in the water the male will not let go. Sometimes the pair sink to the bottom of the pond while others swim to any green plants that may be growing the in water.

Either way the female begins to lay long stings of eggs encased in a clear gelatinous casing. Toads and frogs have external fertilization which means as the eggs emerge from the female into the water the male is applying sperm. If the pair are not joined close enough together the sperm won’t be applied to the eggs and the eggs won’t develop. This is why the male grabs the female so tightly and won’t let go. This is also why he is smaller.

Egg laying can go on for a few minutes or several hours. The strings of eggs cling to the bottom of the pond or the plants growing in the water. Once the female has deposited her eggs the two will break up and the male will go back to calling for another female. The water temperature will incubate the eggs and within a week or two tiny tadpoles will emerge from the eggs and a new generation of toads will inhabit the pond. Until next time…