Roadkill

Recently, when we were exiting the highway and rounding the curve of the exit ramp, we were surprised by the sight of four large Turkey Vultures in the middle of the road in front of us. They were picking over the remains of a porcupine, nature’s clean-up crew in action. Three took flight as we approached, but the fourth held his ground, and I was able to take this photograph from where we had stopped at the side of the road.

The expansion of the road system has been good for Turkey Vultures, but not so good for pretty much any other member of the wild kingdom. One optimistic take on roadkill suggests that the numbers of dead animals littering the road is a good sign, an indicator that there are plenty of others living in the woods. Sadly, the real truth is that plenty of roadkills are only a sign of one thing: more roads.

Check out these two maps. The first shows the Southern Ontario road network in 1935, while the second shows the same region in 1995. The growth in our road network is glaringly obvious.

In fact, you are never more than 1.5 kilometres away from a road in Southern Ontario. Nor is it simply a matter of more roads. The quality of the roads has changed too. The graph below shows how, where once roads had mostly gravel or even dirt surfaces, the majority are now paved.

Paved roads mean cars travel faster. Cars travelling down a paved road are generally moving at a speed that is incomprehensible to an animal. An animal may dart across the road in front of an approaching car feeling safe in the knowledge that it can escape well before, say, an approaching fox could nab it. Or, in the case of a porcupine or skunk, safe in the knowledge that its natural defenses will protect it from all comers. In this they are sadly mistaken. Cars defy the rules of the natural world.

It’s not only the cars that kill animals. They are also impacted indirectly by road construction. Important factors include things like lose of habitat. There are also less obvious impacts. Road salt, for instance, is washed off roads and into waterways, where it disrupts the natural salinity of watersheds. The map below shows the salt burden born by roads. Southern Ontario is heavily impacted. Roadkill as a sign of a healthy population? Probably not.

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Sweet Rocket

One of the early-summer bloomers lighting the garden right now is Sweet Rocket (Hesperis matronalis). Sweet Rocket is a common old-fashioned garden plant that is known by many names. According to Wikipedia, these include Dame’s Rocket, Damask Violet, Dame’s Violet, Dames-wort, Dame’s Gilliflower, Night Scented Gilliflower, Queen’s Gilliflower, Rogue’s Gilliflower, Summer Lilac, Sweet Rocket, Mother-of-the-evening and Winter Gilliflower. The genus name, Hesperis, is Greek for evening, and was probably chosen because the scent of the flowers becomes more conspicuous towards evening. I can’t vouch for this personally, however, because the mosquitos that appear in swarms in the evening discourage lingering for flower sniffing.

Sweet Rocket was probably introduced to North America from its native Europe in the 17th century and has since made itself right at home on its adopted continent. It is a prolific seed producer and can now be found along ditches and woodland edges over a wide range. The plant pictured here was already in the garden before I arrived and I have to admit that I didn’t recognize it at first. Like many others, I initially mistook the plant for a variety of phlox, but upon closer examination, it is easy to tell the two apart. Sweet Rocket is a member of the mustard family, and like all mustards, the flowers have four petals rather than five as does phlox. If you look closely, mustard flowers also feature 6 stamens, 4 tall and 2 short.

As these photographs show, the Sweet Rocket flowers are appreciated by pollinators such as the Tiger Swallowtail butterfly and bumblebee shown above. However, if it weren’t already here, Sweet Rocket isn’t a plant I would chose to add to the garden because it is considered an invasive species. The Ontario Exotic Species Ranking system has four categories, and Sweet Rocket is placed in Category 1 with the worst offenders. Category 1 plants are described this way:

Aggressive invasive exotic species that can dominate a site to exclude all other species and remain dominant on the site indefinitely. These are a threat to natural areas wherever they occur because they can reproduce by means that allow them to move long distances. Many of these are dispersed by birds, wind, water, or vegetative reproduction. These are the top priority for control, but control may be difficult. Eradication may be the only option for long-term success.

Sure enough, a quick look along the river banks and roadsides reveals plenty of escapees. Given the highly-disrupted agricultural landscape around here, it’s probably not a big issue in this area, but invasiveness is certainly an important feature to keep in mind when planning a garden. For a list of the four categories of invasive plants to avoid, check out the Invasive Exotic Species Ranking for Southern Ontario. Another excellent source of information is the Ontario Invasive Plant Council site, which features a guide to alternatives to invasive species that are often planted in gardens. Follow this link to Grow Me Instead!

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