Your Nature Guide for the week of October 4-October 10
The trailing vines that were so noticeable in summer when they quickly
colonized the new clearing below Helliwell House, have started to die
back, revealing the ripe fruits. Close inspection shows that most of the vines
are Bur Cucumber. The fruits, which are
like clusters of burnt almonds covered in long hairs, are
quite distinctive and very different from the other native cucumber at
Todmorden, the Wild Cucumber. Bur Cucumber can invade fields adjacent to
damp woods, and corn growers often have to control it. Introduced to
Europe, it has become a problem in several countries and it is considered
an invasive in Italy.
Most of the wildflowers have finished blooming, but some of the most resilient
are still flowering. In open areas, look for the blue-flowered
asters (both purples and whites), and the yellow
Insect activity has declined substantially, but the
field and tree crickets
can still be heard, if not with their previous intensity. Many of them are
laying eggs--the field crickets in damp, sandy soil, the tree crickets inside the twigs
of trees and shrubs--which will overwinter and hatch next spring.
One of the earliest trees to "turn" in fall is White Ash.
Its leaves change to a deep purple-red, quite unlike most other trees.
At Todmorden, White Ash, along with Sugar Maple, is being planted extensively.
Both species share a handy identification trait: opposite branching, and are easily the most common
native trees with this feature.
There the resemblance ends, as Ash has a compound leaf comprised of 7-9 leaflets,
whereas Sugar Maple has the familiar simple, lobed leaves.
This spring, hundreds of small ash were planted on the eastern slopes, and a check recently shows that
nearly all were leafed out and looking healthy.
Ash trees have been a favourite of urban foresters, and many of Toronto streets
are lined with Green Ash, a native species which is quite tolerant of pollution and salt,
and the European Black Ash.
At present, the distinctive paddle-shaped fruit are dropping onto sidewalks throughout
The oxbow at Todmorden is an old arm of the Don River, severed when the
Parkway was built in the late 1950s. Today, instead of watching salmon
cruise through the Preserve en-route to spawning grounds in the
headwaters, we must content ourselves with minnows and sticklebacks.
These, by the way, have colonized naturally, perhaps repeatedly, when the
Don River floods and backs up through a culvert into the Preserve; the
last time this happened was in 2001.
Salmon are again migrating up the rivers around Toronto to spawn and
while they bypass Todmorden Mills, it is still possible to watch them at points along
the Don River.
The salmon we can see today are Coho and Chinook
Salmon which were introduced to Lake
Ontario in the late 1960s as predators on alewife, itself an introduced
fish. Initially the salmon populations were sustained by hatchery fish,
but today there are established wild populations of these two species.
Nature Notes is researched and written by Mike
Dennison and Alejandro Lynch, and is published each week
by Hopscotch Interactive (www.hopscotch.ca). In
addition to this online version, Nature Notes is
available as a print-friendly PDF and as a text-only email
version. Please contact Mike Dennison to receive these,
or for more info (tel: 416-696-7230, email: firstname.lastname@example.org).