2018-06-09 / Columnists

Nature Notes

Spring Peepers Provide Evening Chorus
By Patricia Martin

It’s always amazing to me how much different the sounds, sights, and smells of Mackinac are at different times of the day. Early in the morning, going up to feed my horse, I am greeted with the cooing of the mourning doves and the singing of the northern cardinals in the cedar trees up the East Bluff. During the day it is the clip-clopping of horse’s hooves and the laughing and talking of families on the road, with the occasional yelling, a boat whistle, and even the sounds of a cannon. During the middle of the day, in the woods, you might hear the call of a pileated woodpecker or the song of the black-throated green warbler and, by the shore, the sound of a gull. The evening and the night are quite different. If you get out of town a little bit, the sounds of people disappear. If you are near the shore, you might hear the lapping of the waves or the sound of a merganser taking flight. I don’t go out at night much any more, but on Memorial Day I went out to a friend’s house for dinner and a bit after 10 p.m. biked home along M-185.

Northern Spring Peeper Northern Spring Peeper It was a beautiful night, very pleasant, with little wind, and the moon was so bright that I didn’t really need a bike light. As I neared the wetlands just past Scott’s Shore Road, I began to hear a chorus of sound. When I neared the ponds and fens (the area along Lone Lake also known as Carver Pond), the chorus would suddenly stop and then, as I passed, it would begin again. It happened several times. It was the chorus of northern spring peepers.

Northern spring peepers have the scientific name Pseudoacris crucifer crucifer and are commonly found through the eastern United States and eastern Canada. These are small frogs about 0.75 inch to 1.5 inch long and weigh in at 0.11 to 0.18 ounce. Their coloring may be brown, tan, olive-green, or gray with expanded pads on the tips of their toes. The “crucifer” part of their scientific name comes from the dark colored slanting stripes that usually merge to form an “X” on their back, although some have incomplete crosses or have spurs or bars. The Latin name crucifer means crossbearer. A slight ”V”-shaped line runs between the eyes, and there is usually a dark strip from the nostril to the eyes. The upper surfaces of the legs usually are barred and the belly is white, cream, or yellow. In response to its mood or surrounding, this frog can lighten or darken its coloring. The male northern spring peeper is slightly smaller and darker on average than the female, and the males usually have a dark throat.

It is the “song” of this frog that usually catches people’s attention. It can be heard for one to 2.5 miles away. This frog uses its vocal sac, which expands and deflates like a balloon to create a short and distinct peeping sound, which can occur about once per second. The vocal sac, when fully expanded, is rather large compared to the size of the frog. The sound is used to attract mates; however, the male peeper may also give a lower-pitched, thrilled whistle, which it does when another male moves into its territory. As their common name implies, the spring peeper’s call is similar to that of a young chicken, only much louder and rising slightly in tone. In a chorus, when many are singing, the song may resemble sleigh bells jingling. They are among the first frogs in the region to call in the spring, and we usually hear them in late April and early May, not too long after the ice has melted. The calling is usually most intense on warm, damp nights, although they may call in the day if it’s damp and rainy. Males sing from the water’s edge of a pond while partially submerged or from an elevated perch, like a clump of grass. Most of the breeding occurs in April and May, although the choruses can be heard into June. Occasionally they can be heard again in late summer or fall, usually away from the breeding ponds.

The female northern spring peeper appears to be attracted to the male with the louder and faster call, which are usually the larger and older males. The female approaches and contacts her chosen mate and after amplexus, the female will produce 750 to 1,300 eggs, which she will attach singly or in small clusters to twigs or aquatic vegetation. In about four to 15 days the tadpoles hatch and they may grow to about an inch in size and are usually brown or green with gold metallic flecks on their backs. The tail fins may be clear or orange with dark blotches. In six to 12 weeks they transform into frogs and are ready to leave the water.

Spring peepers live in temporary or permanent ponds, marshes, and ditches to breed, but after the season they will disperse into the woods, old fields, and shrubby areas. As adults, they eat small invertebrates, like spiders, mites, ticks, ants, and beetles, but as tadpoles, they’re vegetarians, feeding on algae and rotting vegetation. As tadpoles, they may become food for dragonfly nymphs, spiders, and diving beetles, and as adult peepers, birds, fish, snakes, and larger frogs eat them. I guess they all have a taste for frog legs.

One may wonder how they survive the cold winters on Mackinac. When the northern spring peepers crawl beneath leaves, rotting logs, and bark, their bodies produce a glucose based “antifreeze” that causes the extra cellular spaces, rather than the body’s cells, to form ice crystals. It is amazing, but these small frogs can live on average about three years.

Get out and hear their chorus while you can.

Trish Martin is a year-around resident of Mackinac Island, has earned a master’s degree in botany from Central Michigan University, and owns Bogan Lane Inn.

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