Walk Softly – Frogs of North Durham and the Kawarthas

by Geoffrey Carpentier

Last column, I spoke about salamanders and newts, so today I’d like to introduce you to the rest of the amphibians, the nine frogs and one toad which occur in North Durham.

As soon as the ice is off the ponds, I eagerly listen for the soft peeping whistle and plaintive trill of the Spring Peeper. This tiny treefrog (4 cm), to me, is the true harbinger of spring, but don’t be fooled, for it can sing throughout the summer and well into autumn as well. Not easy to see, it hides in the water, partially concealed by vegetation as it sings its love song. Upon closer scrutiny, you can see the tan body with a distinct “X” on its back. Although not too fussy about where they breed, they do seem to prefer ponds in forested areas. Unlike other treefrogs, they rarely climb, and once the breeding season is over, spend most of their time away from water on the forest floor. Like many other species in our area, they overwinter under logs and loose bark, as they are very cold-tolerant, surviving harsh winter conditions, to emerge early in the spring. 200 to 1500 eggs are laid in small clusters, amongst submerged vegetation. Three weeks later they hatch and then 2.5 months after that they morph into adults.

The Mink Frog occurs only on the moraine and northward. It is medium-sized, mostly green, with a brown blotchy back and it has a rather stinky odour, much like that of a mink. It's call sounds like repeated hammering. Similar in appearance to the Green Frog, its hind legs do not have any dark bands below the knees. Highly aquatic, they tend to prefer large bodies of water, where breeding takes place in early summer, when 500-2000 eggs are laid. After the eggs hatch, Mink Frogs will be in the tadpole stage for a year, and then it takes another year before they mature.

One of my favourite frogs is the diminutive Wood Frog. It may be reddish, dark brown or even tan, but it's distinguishing feature is the black mask it sports. Sounding a bit like a duck, they quack to find a mate. Preferring moist woods, with vernal ponds, for breeding, it spends the summer foraging amongst the leaf litter or under rocks and logs, on the forest floor. The female will lay up to 2000 eggs early in spring, in a fishless waterbody. They are aggressive breeders and may form breeding balls, where many males are attracted to a single female. Eventually one or more succeed and the eggs are fertilized. Once the young hatch, they mature in about 2-3 months. Like so many other frogs, they can almost freeze solid and still survive. Not afraid to travel, they move overland freely, between breeding ponds and feeding areas, where they hunt terrestrial invertebrates.

The last two species, we encounter in our area, are the Northern Leopard and Pickerel Frogs. It is unclear if the latter actually occurs in our area now, but circumstantial evidence suggests it may have at one time. Similar in appearance, these two species are covered with many spots and blotches of dark skin, over a base of brown (Pickerel) or green/brown (Leopard). The Pickerel Frog’s spots are angular and usually arranged into two rows down the back, whereas the Leopard’s spots are rounded or oval and in a more random pattern. The Leopard Frog is an average-sized frog (up to 11 cm) which travels long distances from water, often using different bodies of water for breeding vs. feeding vs. overwintering. Breeding takes place in larger bodies of water, where 600-3200 eggs are laid in masses on submerged vegetation. One to three weeks later they hatch and the tadpoles forage for small invertebrates, over the next 2-4 months, before they morph into adults. Winter is spent in the mud in lakes which don’t freeze solid to the bottom. The Pickerel Frog is similar, in many ways, to the Northern Leopard, except, it lays only about half the number of eggs and is a bit smaller in size.

Next time, I’ll finish the story and tell you a bit about our other species of frogs.

Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line on LinkedIn, Facebook and Instagram.