I have been hoarding these photos for a couple of weeks now. For various reasons, I didn’t get around to posting about them immediately after I took them, but neither did I just want to throw them into my catchall piles. So they’ve been sitting in my “to-post” file while I awaited an opportunity to talk about them.
I came across this frog while visiting my parents’ old home a couple of weekends ago. I had brought my mothing equipment with me and set up a couple of blacklit sheets in the yard. It was as I was heading around to check them that this little frog hopped in front of me. A year ago I had something very similar happen with a Wood Frog, in nearly the same place. This year, it was a Spring Peeper, Pseudacris crucifer.
Peepers are tiny frogs. They’re the smallest species found in Ontario, at an inch long or less. This makes them difficult to spot out in the waters of the vernal pools they inhabit in the spring. However, they’re certainly not difficult to hear. Pound for pound (ounce for ounce?), they’re one of the loudest animals. Their high-pitched peeps can reach levels of up to 90 decibels or more. Since they’re not trying to draw females in from across broad distances, the explanation for the noise is likely a result of sexual selection. A male’s vocal mechanism can make up as much as 15% of his body weight. The bigger and stronger his voice-box and amplification, the louder the noise he can produce. So females gravitate to males who can peep the loudest and the fastest. Over evolutionary time, this would drive up the amplitude of the male peepers’ noise. Standing beside a whole pond-full of male peepers giving it their all can cause your ears to ring. At 90 dB, prolonged exposure can actually cause hearing damage. Unsurprisingly, frogs have evolved a method of protection from their own noise.
The scientific name, crucifer, meaning “cross-bearing”, refers to the dark X on the frog’s back. They’re usually variations on brown, though some may be grayish. You can tell the sexes apart by size (females are larger), but also by the colour of their throat – those of females are pale, while males’ are pigmented. I suspect this individual is a female.
Although they don’t climb trees, they have excellent sticky pads on the ends of their toes that allow them to grip vertical surfaces such as rocks or vegetation. This gal used hers to climb out of the yogurt container I had placed her in while I got my camera. Interestingly, they had once been placed in the same genus as the Gray Treefrog, Hyla, before being assigned to the genus Pseudacris, the chorus frogs.
This time of year peepers are caught up in the drive to make more of themselves. In northern climates such as ours they breed from late March to June, but in southern regions such as Florida, their breeding season is October through March. The female can lay as many as 900 eggs each spring. Considering that in order to maintain stable population levels a single frog must successfully make one offspring within its lifetime (therefore a pair must produce two), the percentage of eggs that make it to sexual maturity must be exceptionally low for females to need to produce 900 eggs. If even as much as 1% of eggs made it to sexual maturity, there’d be an incredible population boom (1% = 9 eggs). Most eggs and/or tadpoles will probably be eaten by predators, or suffer dessication before they are ready to leave the water if their vernal pool dries up too early. A success rate of just 2 eggs is equal to about 0.22%.
Through most of their range they are simply known by the common name Spring Peeper, but they have some delightful local names (or at least, according to various sources on the web). In New Brunswick they are often called “tinkletoes”. In some parts of southeastern US they are known as “spring creepers”. In Martha’s Vinyard they’re “pinkletinks”. But my personal favourite comes from western Pennsylvania, where they have the delightful name of “peedee dinks”.
Here, they’re just peepers. But the name suits them. Our ponds are all full of peeps at the moment, the males all advertising their studliness. Although we have no ponds right near our house, the sound from the frogs in the ones in the nearby forest carries on the still night air, and I can lie in bed with the window open and enjoy this emblematic sound of spring.