Friday 1 July 2011

The snakes of Ontario -part 2

Part 1 - Eastern Gartersnake, Dekay's Brownsnake, Northern Redbelly Snake, Northern Ribbonsnake
Part 2 - Northern Watersnake, Lake Erie Watersnake, Queensnake
Part 3 - Eastern Milksnake, Eastern Foxsnake, Eastern Hog-nosed Snake
Part 4 - Northern Ring-necked Snake, Smooth Greensnake
Part 5 - Gray Ratsnake, Butler's Gartersnake
Part 6 - Blue Racer, Eastern Massasauga

I will continue this series with some photos of Ontario's most aquatic species of snakes - The Northern Watersnake (Nerodia sipedon) and the Queen Snake (Regina septemvittata)

The Northern Watersnake is a snake familiar to most people who spend any amount of time outdoors. Just about everyone who has been to cottage country has most likely seen this conspicuous snake basking on rock outcrops or swimming along the shoreline. Two distinct subspecies occur in Ontario - the Northern (N. s. sipedon) and Lake Erie (N. s. insularium) Watersnakes.

Northern Watersnake (Nerodia sipedon sipedon)
 The Northern subspecies is found throughout all of southern Ontario, from the north side of Georgian Bay south to Point Pelee. It emerges from hibernation anytime from early April until early May - my earliest date is April 7.

young Northern Watersnake - Waterloo Region

While common throughout much of central Ontario, the Northern Watersnake is much more local in the south. It is absent from large areas, mainly due to extensive agriculture. However, it is still reasonably common near large rivers and the shorelines of the Great Lakes.

Northern Watersnake - Muskoka District

Northern Watersnake - Muskoka District

While generally perceived to be diurnal snakes, they will move around on warm rainy nights throughout the spring/summer. This snake was found crawling around during early April - the peak of salamander migration. Perhaps it had been rained out from where it was taking shelter, or maybe it was just looking for an easy meal.

Northern Watersnake - Waterloo Region

Northern Watersnake - Waterloo Region

Speaking of diet, the Northern Watersnake is quite opportunistic. In areas near the Great Lakes it is occasionally reported to take dead/decaying fish. Normally, their diet consists of frogs, snakes, fish, tadpoles, and other small vertebrates.

Northern Watersnake - Muskoka District

Lake Erie Watersnake (Nerodia sipedon insularium)

The Lake Erie Watersnake is restricted to 15 islands in southwestern Lake Erie - 4 in Ontario and 11 in Ohio. Additionally a small area on the Ohio shoreline has Lake Erie Watersnakes. This subspecies has one of the smallest known ranges of any North American snake (about 24 square kilometers), with numbers declining steadily. When the COSEWIC report was written for this subspecies, the total Canadian population was estimated at 565 animals - warranting good reason for its Endangered Status.

Lake Erie Watersnake - Essex County

As you can see from the above photo, the Lake Erie subspecies differs significantly from the Northern subspecies. The dorsal color is unique among all watersnakes, being slate-gray. Additionally, most mature individuals do not have obvious blotches or bands. Some say that this coloration is an adaptation to the limestone rocks in which these snakes spend the majority of their lives as an all gray snake is harder to detect by a gull or other predator when it basks on limestone rocks.

Lake Erie Watersnake - Essex County

I have had the pleasure of spending a good amount of time on Pelee Island, an area with a relatively high density of Lake Erie Watersnakes. In suitable habitat, they can even be quite common (I remember one herp survey where we tallied over 150 individuals in a weekend). Unfortunately I haven't been over in a few years, but hopefully that will change soon!

Lake Erie Watersnake - Essex County

Its somewhat interesting that in recent years their diet has shifted to consist primarily of the invasive Round Goby, especially dead individuals that wash up on shore. Other commonly taken prey items include Mudpuppies (Ontario's only exclusively aquatic salamander), logperch, and other darters.

Obviously, these snakes are quite variable, as you can see in the following picture...

Lake Erie Watersnake - Essex County

Here's one of my favorite shots of the species - basking on a limestone outcrop overlooking Lake Erie.

Lake Erie Watersnake - Essex County

Queen Snake (Regina septemvittata)
The Queen Snake may not be the prettiest of snakes, but it is my favorite Ontario species. The ecology of this animal is fascinating - they spend their entire life within a few meters of large creeks and rivers, feeding exclusively on crayfish. Perhaps another reason why they are so endearing to me is their scarcity. This is undoubtably the least often reported snake in the province, and a species that I have only seen 9 individuals of, despite having spent a considerable amount of time looking.

Queensnake - Essex County

Queensnake scalation

Queen snakes spend the majority of the day either basking alongside the edges of creeks or foraging for crayfish under shoreline rocks. Most adult Queen Snake will have scars and injuries on their head from the constant rubbing against rocks or from the pincers of a large crayfish.

Queensnake - Essex County

Unfortunately, many of the creeks where Queen snakes have historically been found no longer can support populations. Human persecution is one factor, as is the degradation of water quality and shoreline habitat. Increases in silt in a river, the removal of shoreline vegetation, or the decline of crayfish will have severe impacts on Queen Snake populations. Fortunately though, the Queen Snake is still doing well in the midwest states, even though its Ontario numbers are declining. An example of good Queen Snake habitat:

Queensnake habitat - Brant County

A few more shots of this fascinating snake...

Queensnake - Middlesex County

Queensnake - Brant County

Coming up in the 3rd (of 6 installments) - a closer look at some of the larger snakes in Ontario: Eastern Milksnake, Eastern Foxsnake, and Eastern Hognose Snake.


Brandon Holden said...

these photos are spectacular! Looking forward to the next round

goatgirl said...

Thanks for the pics. I found a Northern Watersnake, and thanks to your EXCELLENT photos, the face and markings-I identified it! Jen