The Amazing Wood Frog

In early April the skim of ice on a shallow, ephemeral pool finally melted. The next day, an inviting afternoon sun led me back to the pool, camera in hand. This is a ritual of Spring that’s been repeated since I created the micro-habitat in a wetland 30 years ago. Less than 15 feet across and about a foot deep, the “pothole” is a breeding habitat for dozens of wood frogs. A subsurface layer of clay retains water in Spring and early Summer – in most years, sufficient time for the metamorphosis of tadpoles to frogs.

Built for the cold, the Wood Frog (Lithobates (Rana) sylvatica) ranges far north into Canada and Alaska – farther north than any other reptile or amphibian. Their adaptation to the severe cold and erratic Spring weather of northern climes is unique. They’re freeze tolerant and breed explosively in a narrow window of opportunity. This story – starting with the appearance of more than 30 active frogs and ending with masses of eggs (and no frogs) – occurred in about three days.

The majority of the frogs were males, distinguished by their dark, mottled brown coloration and size (smaller than females; about two inches long).

The small size of the vernal pool and a predominantly male population led to frenzied chasing and breeding activity. At times, the water boiled with chaotic activity as a large number of males chased and converged on a female.

Occasionally, the female, larger and more colorful than the males, could be seen at the center of the fray.

A breeding male grabs the female, hooks his thumbs around her (amplexus) and holds on until eggs are deposited.

Soon, surprisingly large masses of eggs appear. Mission accomplished!

Most offspring that survive a year – relatively few – will return to this natal pool to breed. I’ll be ready, with a slightly larger and enhanced wetland stage for their performance.

Wood frogs are fairly common in forested wetland habitats, but we must be mindful of their complex habitat needs and practice wetland conservation on a broad, landscape level. The conservation of small, temporary wetlands and vernal pools is critical. They aren’t protected and often fall victim to leveling and grading, heavy equipment operation, development and other destructive practices. Additionally, wood frogs are woodland creatures that rely on a variety of habitats (more so than most frogs). They wander far and wide in moist woodland habitats adjacent to their natal pools and also hibernate on land – under leaf litter, rotting logs, rocks, etc. Forest management practices should take this into account.

Photos by NB Hunter (April, 2019). © All rights reserved.

 

 

13 thoughts on “The Amazing Wood Frog

  1. These images are fantastic, Nick! Our pecan orchard wetlands (where the slough runs through the property) supports many species of frog and other water life. I am in awe of your ability to photograph the mating and egg laying process – those endeavors take a lot of time and patience. I might just have to get our little two-man boat out and float around… patiently waiting!

    • Love when you find the time to comment – always informative and motivating. I just finished some modest clearing around the little vernal pool. Willow shrubs are taking over the wet flat, absorbing a lot of water and casting too much shade. They’re also reducing the local population of Turtlehead wild flowers which are the primary food of Baltimore Checkerspot, a threatened butterfly. When the frogs are gone and the pool dries out – usually in July and August – I’ll work the perimeter with a shovel and remove some of the organic debris in the pool itself in order to increase the diameter and depth. Your Pecan wetlands sound like a place I would enjoy. You’re fortunate. I think it’s more important than ever to not only enjoy, but preserve and enhance wetlands. Enjoy!

    • Thanks Donna. It’s a good feeling to know that a subject like this is appreciated. Aside from the thrill of studying this phenomenon at close range, I enjoyed experimenting with the effects of light from different shooting positions.

  2. Fantastic images and narrative! Your patience and perseverance is quite apparent in this post. It’s always a joy to view one of your offerings. Have you encountered tales of some fungus that is wiping out whole colonies of frogs? I’m worried that the little pond we created hasn’t had any signs of our little guys. My memory is being obstinate with the name of our bunch. Springtime we usually have a small waterfall coming down the concrete steps and the frogs are often seen sunning themselves on the steps.

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