Prothonotary Warbler

Prothonotary Warbler

Tuesday, 26 January 2016

Goodness Snakes Alive!!

Pelee Island is famous, or perhaps infamous depending on ones view point, for its snakes. Some of the islanders cringe when this is mentioned, however, and are quick to point out many other more endearing aspects of this fair isle. Somehow myriad large and small slithering creatures aren't appreciated by everyone!

Nonetheless snakes have survived fairly well, although two species of rattlesnakes have not been seen for decades.The big three are: Blue Racer, Lake Erie Water Snake and Eastern Fox Snake. All three are Endangered in Ontario.

A smaller but also interesting snake is the melanistic colour form of the Eastern or Common Gartersnake. It is almost entirely black, and is fairly abundant on Pelee Island. It also occurs on the Lake Erie Sand Spits of Point Pelee, Rondeau and Long Point. Presumably the dark colour enables it to warm up a bit more quickly on these areas that are typically influenced by the cooling action of the lake.
Melanistic Eastern Gartersnake
Blue Racers used to occur on the Ontario mainland, but have not been conclusively documented here for several decades. so as far as anyone knows, the only Ontario location for them is on Pelee Island. It is a beautiful species, if I can use that term. Their bluish gray colour in combination with the black mask is really quite attractive. They can grow to almost two metres in length.

Blue Racer
They are elusive at the best of times; if they sense impending danger, they will move very quickly. During the hot part of the season, they will spend their time underneath the dense thatch on the ground, or be up in the trees! So little was known about them even on Pelee Island that no one was able to undertake any meaningful research on them to determine what the population might be, where they spent their time above ground or where they hibernated. That began to change when during a Life Science Inventory I coordinated back in 1988, we narrowed some possible hibernation sites down. Fast forward to late April of 1989 when a biologist colleague of mine went over to the island with me, and the weather seemed about perfect for snakes to be out. I suggested that we check out one of the most likely spots, and in a matter of an hour, saw 14 large adults, and heard a few others rustling away in the brush and debris. Bingo! And with that, a keen snake researcher was able to capture enough individuals to put radio transmitters in them and follow them around for three seasons, documenting their daily and seasonal movements. So much was learned (he got a M.Sc. out of it too). For example, on average a male Blue Racer had the largest home range of any snake in North America. Most of their preferred habitat looked something like this.
 Or this.

Their territory averaged approximately 202 hectares. And some actual hibernacula entrances were discovered.
Hibernaculum entrance of Blue Racer
The entrance isn't much to look at from the surface, but led to an underground cavity which met their winter requirements, and that is what counted. The entrance could be just a hole in the ground or a hole in the rock.

Hibernaculum entrance of Blue Racer
Eastern Fox Snakes are one of the other big three, although they are fairly common on parts of the mainland. They occur even up along the east side of Georgian Bay, but that population is isolated from the southwestern Ontario ones. The species' entire world range is situated around the lower Great Lakes.
Eastern Fox Snake
It is distinctive and attractive in its own right. They are often heavier bodied than Blue Racers, and generally don't move as quickly. They do occupy some of the same types of habitat, although will be more often found in wetland habitat than racers. Both species lay eggs in rotting material, such as a hollow rotting tree trunk or a pile of rotting straw.

The other one of the big three is the Lake Erie Water Snake (LEWS). It isn't a true species in itself, as it is a subspecies/colour morph of the much more common Northern Water Snake. But the LEWS is different because it seldom is as dark brown and usually has less distinct cross banding. This is highly advantageous for them as they spend a lot of their time on the dark gray limestone shorelines of the Erie Island, and blend in better. When they are at the more vulnerable youngster stage, this is definitely an advantage so they don't get picked off by hungry gulls or herons. They are restricted to some of the Erie Islands and the Catawba/Marblehead Peninsula of Ohio.
They spend most of their time close to water, often basking on the rocks that line the shore. If danger comes by, they can make a quick exit into the water, where they are expert swimmers and one of the only snakes that can swim underwater.

Even their hibernacula are seldom more than 100 metres from shore. They often hibernate communally, and when they emerge in spring, can sometimes be found in numbers, such as this next image shows. This was taken at the edge of an abandoned quarry very close to the lake, and provided a perfect location for them for many of their seasonal requirements.
As is the case for many Species At Risk, there often are some restrictions to developers and the like, when an area is proposed for development. So just like the research with the Blue Racer, a colleague of mine decided she wanted to do some radio-telemetry with the LEWS to determine some of the life cycle activities of this species, including where they were hibernating. Since LEWS spends most of their time within a 100 metres of the shoreline, and that is exactly where a lot of the development on Pelee Island was focussed, this would be valuable information indeed. This first image shows Deb Jacobs, the researcher, inserting a small chip about the size of a grain of rice, subcutaneously into the snake. Each chip has its own number, so when this snake is caught again, a chip reader can tell exactly which individual it is. Another colleague, Ron Gould, is holding the snake during this brief operation.


A few LEWS had radio-transmitters implanted surgically, so they could be followed without actually seeing the snake. The transmitter would give off its own signal so even if it was underground, its location could be determined. This next image shows Deb with the receiver and antenna in hand, tracking one of 'her' snakes.
There were other activities focussing on snakes, including LEWS. There were summer students getting a first hand look at some of these endangered reptiles, and seeing a dedicated researcher in action. Admittedly some of it was grunt work, as the next image shows, but they didn't seem to mind. Here they are lifting heavy limestone slabs in case a LEWS was hunkered underneath.
Occasionally one would find a dead LEWS washed ashore. This one may have been hit by a boat propeller. They will venture out into the water quite freely. In fact one snake that had been marked on Pelee Island was found later on an island about 11 km away! This one below had been dead for a little while, but the Giant Swallowtail and Azure butterflies seemed to be enjoying the decomposition juices.

If you were to have visited Pelee Island at the time of settlement, you would have noticed that it is actually a collection of several rocky outcrops connected by a lower lying interior, which depending on the lake levels of the day, would likely have been wetland. But eventually settlers dug a canal system and drained the interior wetland, giving Pelee its present day look. Pumping stations on all four sides of the island, such as the one shown in the next image, are connected to an interior canal system which keep the island from flooding.
These stations pump the water into the lake. Since the interior is below lake level, large chunks of armour stone are situated around much of the periphery to protect the interior from wave action and flooding.


Also around the periphery of the island is a ring road system. You can see a bit of it in the background to the right of the image above. Being so close to wildlife habitat, it is not surprising that there are a lot of road-killed critters, such as this Snapping Turtle.....
.....and this Eastern Fox Squirrel. Fox Squirrels are presumably native to Pelee Island, but that is likely the only place in Canada where they are native. They are large and attractive squirrels, but are slow moving. In spite of the low posted speed limits on the island they misjudge traffic with surprising regularity.

Of course with the roads being so close to the water where LEWS occur, there are far too many of them that meet their demise as well. This is particularly the case in the relative coolness of spring and fall when the sluggish snakes are crossing the roads while going to or from their hibernacula. If the pavement is nice and toasty, they may linger for awhile thinking it is a nice place to bask. Unfortunately that might be one of their last thoughts.....
Here is a road-killed Blue Racer, below. At first glance it doesn't look dead....there is no obvious injury....but live ones don't normally stick around, and in the case of this one, its head is flat on the ground, not up and alert, keeping an eye on all that is going on around it.

It is not surprising that cottage owners want a view of the water. Hence that is where most of the development is, and is the greatest threat to habitat such as this, where a seemingly insignificant hole might be the deciding factor on whether one or more snakes lives or dies.



That presented us with enormous challenges in determining the potential impacts on one or more legislated Species At Risk. It is a delicate issue, trying to balance the needs and expectations of prospective landowners and the municipality expecting an increase in the tax base against the needs and survival of Species At Risk. As a result, I spent a lot of time on Pelee Island trying to sort things out!








3 comments:

  1. Al, you say that the Lake Erie Water Snake is not really a species, but rather a subspecies of Northern Water Snake. In the same context, Eastern Fox Snake is thus not a species either, as it too is a subspecies, of Fox Snake. Correct? Of course they are both species, just depends on what you want to call them.

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    1. Al: to reflect the current taxonomy, LEWS is a subspecies (Nerodia sipedon insularum). At one point it was just thought to be a colour form, a reflection of its being only present on limestone islands and adjacent areas of Lake Erie, but could easily interact and exchange genetic material with the Northern Water Snake since their ranges overlap.

      Eastern Fox Snake used to be a subspecies with the closely related Western Fox Snake and were in the Elaphe genus. In 1997, it was decided that the two warranted separate species status for various reasons. The two species ranges were quite well separated by several hundred kilometres. So Eastern Fox Snake retains its common name, but is now a distinct species and is known as Pantherophis gloydi. Western Fox Snake is Pantherophis vulpina.

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    2. Al, I did not know that Eastern Fox Snake was recently separated out as a full species. Thanks for the explanation!

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