This winter brought Tundra Swans very close to us, just south of Georgetown during April. The agricultural fields southeast of Mountainview and 10th Side Road also hosted Canada Geese, Caspian Tern, and nearby Ring necked Duck, Lesser Scaup, Bufflehead, Ruddy Duck, Coot, Mallard, Redhead, and 7 Hooded Mergansers were seen on one visit by Dave Williams. Who needs Lake Ontario when the birds will come to us!
In 2012, Credit Valley Conservation inventory staff discovered a provincially and nationally rare phenomenon along the Niagara Escarpment at Silver Creek and Belfountain. This discovery was of tufa, a soft rock, being actively formed at the emergence of select springs. Tufa is a variety of limestone. It differs from typical Escarpment rock formed on ancient sea beds from calcium-rich shells, exoskeletons and coral. Instead, tufa is formed by calcium precipitated out of water. Bits of the precipitated calcium carbonate can amalgamate to create larger rocks.
Ontario’s known tufa deposits are formed at springs and waterfalls, particularly along the Niagara Escarpment. Tufa is only known in Ontario from Brantford, Paris, Dundas, Niagara Falls, and with the discoveries reported herein, Silver Creek and Belfountain. In 2008, the Ontario Ministry of Natural Resources designated a tufa deposit in Brantford as a provincially significant Earth Science Area of Natural and Scientific Interest.
Tufa only forms at springs where just the right conditions exist. First, ground water must contain carbon dioxide picked up from the air, making the water weakly acidic. Second, the ground water must become supersaturated with soluble calcium by dissolving limestone. Third, as the calcium-rich water emerges from the ground, it must release enough carbon dioxide to cause the soluble calcium to solidify into insoluble calcium (rock). The same precipitation process is responsible for the formation of stalactites and stalagmites in caves.
Tufa was first found in the Credit River watershed by the author and assistant Pete Davis at Silver Creek Conservation Area. The author recognized it based on tufa deposits seen on a Hamilton Naturalist’s Club hike to Spencer’s Gorge (Dundas) led by Dr. Terry Carleton, a forestry professor at the University of Toronto. Dr. Carleton was the first to document tufa deposits at Spencer’s Gorge, which he recognized based on his observations of similar occurrences in England. News of the discovery at Silver Creek led to CVC’s Scott Sampson reporting possible tufa at Belfountain Conservation Area. A visit by the author, CVC’s Dawn Renfrew, biologist Lynda Ruegg, and Dr. Carleton confirmed the report.
Tufa deposits at Belfountain may be more abundant than anywhere else in Ontario. Tufa deposits can be easily observed at this conservation area on north-facing slopes. The best viewing spot is from the foot bridge that spans the West Credit River. The largest and most impressive tufa deposit can be seen from here on the slope on the south side of the river. This tufa deposit is almost completely covered by a blanket of moss in shades of green and red, with a small patch of whitish tufa peeking through.
Tufa deposits are a challenging growth environment for plants because soil is absent, the substrate is rock, conditions are calcareous, and there is a constant flow of cold water. Few plants can function in such environments; many of those that can are mosses, especially those specializing in seepy, calcareous habitat. Our tufa deposits, if not barren, tend to be either dominated by mosses, or populated by hardy plants such as Watercress (Nasturtium sp.), Jewelweed (Impatiens sp.) and European Coltsfoot (Tussilago farfara). The dominant moss on Silver Creek and Belfountain tufa deposits is Cratoneuron filicinum. It is not a rare moss, however, there are some provincially rare mosses known to grow on tufa that could be found in future inventories. Interestingly, because photosynthetic activity removes carbon dioxide from the spring water, mosses and other plants actually help create more rock once they become established.
In addition to potentially supporting rare mosses, tufa formation areas may also act as amphibian and dragonfly/damselfly breeding habitat. This is because tufa is often formed on slopes, creating terraces on which small pools of water are formed. Evidence suggests that salamanders (some of which are Species At Risk) may breed in these pools, and as some dragonfly/damselfly species restrict their breeding areas to seeps, they may also be found in these tufa pools. These spring-fed pools may also be an important water source for wildlife, especially if they remain unfrozen in winter months.
Tufa formation is a topic only recently receiving attention amongst biologists, and with increased awareness, the author expects more tufa deposits to be found in the future along the Niagara Escarpment.
Credit Valley Conservation
It’s a lovely time of year to get outside for a romp through a nearby forest. By braving the mud and puddles, you can often be rewarded by some solitude from the regular summer and fall crowds, and wildflowers in spring are quite a sight.
One of the best-known flowers of spring is the White Trillium (Trillium grandiflora), our provincial flower. In fact, if you encounter any Trillium in our watershed, it is likely to be this one. Its large petals give it an alternate name of Large-flowered Trillium. Its petals are the longest of the four trilliums in our watershed. Its petals are indeed white, but can take on a pinkish hue with age. It is found in rich deciduous woods and often grows so abundantly as to appear to carpet the forest floor.
In addition to White Trillium, three other species are found in our watershed: Red Trillium, Painted Trillium and Nodding Trillium. Red Trillium (Trillium erectum) is the second-most common Trillium species in our watershed. It has brilliant crimson petals and is a thrill to encounter. It is reported to have a bad odour, giving it the alternate name of Stinking Benjamin. It is found in moist woods.
Painted Trillium and Nodding Trillium are quite rare in our watershed. In fact, I’m aware of only one location for Nodding Trillium, which is on private land a few kilometres from Caledon Lake. Painted Trillium is also quite rare in our watershed. It was known from only a historic record (1947) for our watershed until quite recently, but Natural Areas Inventory field work done since 2008 has found this species in three natural areas, one of which is Caledon Lake (NAI field work also made the Nodding Trillium observation). Nodding and Painted Trilliums are species of moist woods.
Trilliums are perennials that grow each spring from underground rhizomes. They are long-lived with White Trillium able to live at least 70 years. White Trillium flowers are primarily pollinated by bumble-bees and their seeds are dispersed by ants.
The Natural Areas Inventory (NAI) carries out vegetation community mapping, and performs flora and fauna inventories throughout the Credit River Watershed and Region of Peel. 2012 will be our 5th field season. If fellow naturalists are aware of any locations of Nodding or Painted Trillium in our coverage area, I’d be happy to hear about it.
Credit Valley Conservation
Spring time is a time of new life and new beginnings: trilliums bloom, maple buds burst and red fox kits playfully tussle. At this time adult turtles are also thinking of new life, as they search out mates, breed and lay eggs. Turtles are fascinating creatures: there is fossil evidence that turtles have been around for 200 million years, which means they existed alongside dinosaurs. And turtles survived whatever catastrophic event(s) that led to the extinction of 90% of plant and animal species, including dinosaurs1.
Turtles are tough and tenacious. But the last two hundred years has seen the human population grow exponentially and impact their way of life. We all know some of the changes they’ve faced: wetland draining and filling, hunting, removal from the wild, roads built through wetlands and other habitat, road mortality, intentional persecution (particularly of Eastern Snapping Turtles).
The effect of turtle road mortality in particular is compounded by the inherent biology of turtles. Turtles have a high egg and hatchling mortality rate with very few making it to adulthood. Also, turtles take years to reach sexual maturity, in some cases 15 years or more. So when adult turtles are hit by vehicles, the impact on the population is much more severe than it would be on species which have greater reproductive success (e.g. raccoons). Tenacious turtles are still with us today, but population threats have led to 7 of the 8 native Ontario turtle species being considered species at risk of extinction or of disappearing from the province.
A critical time of the year for turtles is approaching: nesting time. Nesting occurs between late May and July and results in turtles moving around to find breeding partners and nesting habitat. In doing so, they may walk across roads, especially roads near wetlands. They also may use the sandy or gravely edges of roads to nest. While turtles may cross roads from April to October, their movement is at its peak in early summer.
Yes, turtles are tough, but they could use some helping hands. They haven’t evolved to handle humans in automobiles and earth-moving equipment… or maybe it’s more accurate to say that humans haven’t evolved to handle turtles. But some advances are happening right here in our watershed. In 2009, along a stretch of Highway 10 south of Orangeville where wetlands exist on both sides of the road, the Ministry of Transportation installed fencing to keep turtles off Highway 10 and direct them through a culvert under the road.
As early summer approaches, and you watch new life unfold, think of the prehistoric reptiles around you, these creatures of an ancient lineage, learning to cope in a new world with asphalt roads, fences, culverts, and two-tonne vehicles driving 100km/h through their home range. Imagine a turtle on a road shoulder about to cross, its eyes only 3 or so inches off the ground – such a limited field of vision – and knowing it will take some time to get across. I’ve seen a turtle stand on the road shoulder, faced as if it was about to cross, with cars whipping by, and looking like it was trying to find the right moment and work up the courage to cross2. The adult females of at least two of our turtle species risk their lives on dangerous roads due to something called nest-fidelity: the desire to return to where they were born to lay their eggs in the same place. So, many of the turtles you encounter on roads will be females carrying eggs or that have just nested. Like parents of other species, they are willing to put their lives on the line for their young.
So consider lending a hand to the turtles this nesting season. Drive slowly and scan the road, especially around wetlands, and if it is safe to do so, help turtles across roads. Be careful with Eastern Snapping Turtles which can bite (The Toronto Zoo and Kawartha Turtle Trauma Centre have youtube videos available on how to move a turtle across a road). If you encounter an injured turtle, contact the Toronto Wildlife Centre which admits injured turtles for rehabilitation. Consider sending observations of live or dead turtles to an organisation such as the Toronto Zoo’s Adopt-a-pond which runs the Ontario Turtle Tally.
1Some scientists still consider our birds to be descendants of dinosaurs, although recent research suggests otherwise.
2I was able to get this turtle across, but it took me a few minutes to find the right moment, and I had a much better view (and a bright jacket).
by Leanne Wallis
Credit Valley Conservation