As spring advances the world fills with sound. Months of winter’s muffled silence give way to a great symphony of singing, gurgling, croaking, and drumming. Yet what we hear as a joyous ensemble masks some nasty competition.
Birds are the best known chorus members. They communicate a variety of messages to others of their species through song, but mostly they say “stay away from my territory, unless you are a female ready to mate”. Researchers have shown that if a bird is removed from a territory, playing a recording of its song will prevent other birds from occupying the territory.
Not all birds rely upon song for auditory communication. Ruffed grouse cup and then vigorously flap their wings to create a drumming sound. Woodpeckers bang against trees not just to get food but also to communicate. Snipe and woodcock conduct aerial displays where sounds are created by the wind whistling through their feathers.
Frogs and toads also indicate their desire for mating by vocalizing. Spring peepers probably have the best known call. Their clear high peeps have been heard practically year-round, but they are most active between mid-March and June after they migrate from their woodland hibernation hide-outs to vernal pools for mating. Researchers estimate that a single male repeats his call about 4,500 times on any given night. American toads offer another common song. Their high-pitched sweet trill comes from the shores of ponds, lakes, and rivers. Toads begin singing slightly later in the season than peepers.
Frogs and toads that vocalize in the spring time usually produce young that must mature relatively quickly. Peepers and wood frogs rely upon pools that dry up by summer time. Using temporary habitats helps minimize the number of predators their tadpoles encounter, but means singing must start early and mating commence quickly before the pools disappear. Toads and leopard frogs lay their eggs in more permanent habitats, so they can wait a little longer. Still, their tadpoles mature within one growing season so they need to reach adulthood in time to prepare themselves for the coming winter. Tadpoles of bullfrogs and green frogs can overwinter for a year (sometimes even two), so these species do not begin calling until much later in the summer.
Singing is hard work. Not only does the act itself require tremendous energy, but singing also can direct predators to the singer. Indeed, certain parasitic flies have been shown to hone in on singing crickets, another species that uses sound to attract mates. With communal breeding species like spring peepers and American toads, the sheer number of singers can serve to overwhelm predators; the noise can be nearly deafening.
Many individuals skip the hard work and risks of singing. Satellite males hang around the edges of frog and toad choruses and intercept females as they approach. Naturalist Thomas Tyning describes such behavior in American toads: “Some noncalling males patrol the water by swimming about and remain silent. They investigate almost any moving object and attempt to clasp with females, other noncalling males, calling males, or pairs already clasping. In some populations these males are at least equally successful in securing mates as are calling males.”
A few fish species also use auditory cues to encourage mating. In Lake Champlain, male freshwater drum (also known as sheepshead) produce croaks or grunts during the summer spawning season. The sound is generated when specialized muscles around the swim bladder contract acting like drumsticks against the bladder. The website of the Lake Winnipeg Research Consortium notes that, “In the evenings, the calls can become so intense that the sound is often mistaken for distant highway traffic.”
Songs of the natural world are more like bawdy tavern lyrics or imposing “KEEP OUT” signs than exaltations of the soul. Nevertheless, they can fill our hearts with joy.
Lake Look is a monthly natural history column produced by the Lake Champlain Committee (LCC). Formed in 1963, LCC is the only bi-state organization solely dedicated to protecting Lake Champlain’s health and accessibility. LCC uses science-based advocacy, education, and collaborative action to protect and restore water quality, safeguard natural habitats, foster stewardship, and ensure recreational access.
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