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Vail Daily column: The hills are alive with the sounds of toads

Beth Garrison
Curious Nature
Vail, CO Colorado

As the snowy remains of winter continue melting away and the late spring sunshine and warmth awaken the buds of the aspen trees and the blooms of wildflowers, the rivers, mountains and forests around us begin to undergo an annual transformation. Some changes happen very quickly, such as the whitewater of the Eagle River beginning to rage, overtaking the once dry, rocky banks. Other changes happen more gradually and require a keen sense of observation to notice. Surrounding forests and meadows come alive as the quiet nature of winter is slowly overcome by the harmony of returning migrant birds, awakening marmots and hatching insects.

The sound of one iconic summer species that often blends into nature’s summer symphony is the boreal toad. Next time you are walking in the woods and hear what you think sounds like a distant flock of migrating geese, take a look towards the ground rather than up to the sky. Boreal toads, which have recently awoken from winter hibernation and have migrated to their breeding grounds, are instinctively ready to grab hold of one another, literally, and expand their gene pool.

Boreal toads breed in shallow, slow-moving ponds, streams and wetlands created by the melting mountain snow. After waking from a long winter’s sleep, these toads use scent cues to find their way back to their preferred breeding spot, often the place in which they were born. Once they arrive, the male will stake out his territory in hopes of finding an agreeable female. When they find a hopeful mate, the male will use his front legs to grab onto the female and hold tight, a move known in the amphibian world as amplexus.



Occasionally when searching for a mate, a male will mistake another male for a female and take hold. This mistake in gender identity is generally met with a bit of kicking and screaming. Well, screaming is not exactly accurate. The mistaken male produces a high pitched chirp, known as the release call and resembles the peep of a young chick, and aptly kicks the approaching male away. Females wishing to let an approaching male know that she is frankly not interested will also emit the release call until the male so kindly lets go of his grasp. When numerous toads are in one body of water, many of the release calls sounding off together resembles the sound of a flock of geese and is a sound often heard during the day, the toads’ preferred time of day to mate.

When a male boreal toad is successful in finding a partner, the female will lay an average of 5,200 eggs in the water which the male then fertilizes. If you look closely, you may see rows of tiny, black, floating dots in the mountain ponds and streams. These are the fertilized eggs, which will hatch into tadpoles three to 10 days after being laid. The tadpoles develop and grow in the breeding pond for about one month before undergoing metamorphosis and transforming into young toads. The newly transformed toads can be found hopping hungrily around their breeding grounds looking for tasty snacks, like spiders, beetles and moths to munch on.



Boreal toads are the only alpine toad species found in Colorado, living between 8,000 and 11,500 feet in elevation. Over the past two decades, this brownish-green, and warty amphibian with dark blotching on its belly has experienced a significant decline in population in the Rocky Mountains. The problem is so severe that the Colorado Division of Wildlife has classified the toad as an endangered species.

The primary reason for their decline is a disease known as chytrid fungus, which is parasitic and infects the very sensitive skin of boreal toads. In fact, this fungus is negatively affecting amphibians globally. Habitat loss is another factor affecting the decline in populations of the boreal toad. The state of Colorado is taking action by trying to protect boreal toad habitat and re-introducing toads throughout the mountains. Hopefully, this will prove to be an effective means for preserving this species and reversing its endangered status.

As you hike around the mountain, take a few minutes to stop and hear who is around you. With careful observation and good timing, you may just stumble upon this small, but important species partaking in their unique mating ritual and furthering the longevity of their species.



Beth Garrison is curriculum specialist for Walking Mountains (formerly Gore Range Natural Science School) and an avid seeker of hidden creatures big and small.


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