invasive – BIG

Ontario’s latest forest invader looks like “invasive fluff,” says Canadian Forest Service research scientist Chris MacQuarrie. And really, how scary is that?

Plenty scary for anyone who values the province’s dense stands of hemlock.

Despite its fuzzy appearance, the aphid-like Hemlock Woolly Adelgid (HWA) literally sucks the life from its victims—a tiny vampire that “quickly overwhelms the tree’s ability to defend itself,” MacQuarrie says. “It’s another invasive that kills its hosts really quickly and has the potential to change ecosystems.”

The HWA landed in Virginia on Japanese nursery stock in 1951. Since then it has been spreading through the eastern States towards the Great Lakes, riding on infected wood, catching a lift on the wind, or even cruising on migrating birds. In 2017 the HWA was discovered in southwestern Nova Scotia, where MacQuarrie says it’s causing “significant mortality.”

Nature scrapbook: meet the hemlock tree

Now it’s Ontario’s turn. This past summer researchers found the bugs in hemlocks near Grafton. Infested trees were found within about 40 acres of a mixed woodlot, with many displaying extensive damage, though an exact number of trees killed by the pest is not available. The Canadian Food Inspection Agency (CFIA) has delivered a Notice of Prohibition of Movement to the property owner, which restricts them from moving any wood or wood material from their property. The CFIA has provided information to them on the restrictions of movement of hemlock that could contribute to the spread of this pest.

It’s not the first sighting of HWA in Ontario—during the past decade, isolated infestations were wiped out in Toronto and the Niagara Gorge, and another Niagara outbreak is contained by farm fields and development. But the Grafton bugs are close to Ontario’s hemlock heartland, stretching from the Ottawa Valley through Algonquin Provincial Park to the Kawartha Lakes and Muskoka District. If the bugs spread, the ecological impact could be severe: hemlock provide crucial habitat for everything from moose and deer to brook trout and Blackburnian warblers. The trees’ towering foliage also cools riparian areas and buffers shorelines and ravines from erosion.

Battling invasives with slingshots

So while researchers look for ways to control the bug, MacQuarrie’s asking cottagers and landowners to track new outbreaks by scouting for telltale woolly fluff at the base of the hemlock needles, and reporting sightings to the CFIA or the Ontario Ministry of Natural Resources and Forestry.

The HWA secretes this waxy, fuzzy coating to protect and insulate itself and its eggs. Infestations usually start near the tops of the tree and work downward. “Be observant if you see declining hemlock,” MacQuarrie says. “Usually once the insect gets down to eye level it has already been there for a while.”

The double-crested cormorant gets a bad rap. But give this big, prehistoric-looking bird some props: the species’ numbers have exploded since the 1970s, after they suffered at the hands of DDT. Just like eagles, cormorants would eat fish contaminated by the pesticide (and produced eggs with too-thin shells as a result). In 1950, there were only 900 breeding pairs in the Great Lakes. By 2000, that number had jumped to 115,000.

What do cormorants eat?

Some anglers aren’t huge fans of this bird, which, fair enough: it does spend much of its time catching fish. Flocks of cormorants will fly dozens of kilometres from their home base to forage. They soar in tight formations then dive below the surface of the water to catch more than 250 species of fish, including small fare such as minnows and yellow perch, plus invasive species including round goby and rainbow smelt. For the record, anglers, most research shows that sport fish only make up a small percentage of a cormorant’s diet.

Cormorants are excellent swimmers—at least, they are when they’re going after food. This bird has a cool fishing technique: it chases after fish underwater, propelling itself with its webbed feet. (Other bird species that swim underwater, like the Cassin’s auklet, use their wings like fins to “fly” as they pursue prey.) Cormorants have hook-tipped beaks for a reason. They use the hook to snag their dinner. Sometimes they catch crayfish. When they do, they repeatedly bash the crustacean against the surface of the lake until its legs fall off, then flip it into the air to catch and swallow it head-first. Show off.

Why do cormorants ‘pose’?

When a cormorant isn’t fishing, it’s just hanging out. This bird spends at least half of its day resting (hey, sounds like a cottager!). Ever spot one standing on a bare, windy rock or branch—or on your dock—with its wings outstretched? It’s trying to dry out. Cormorants have less preen oil (the stuff that helps ducks shed water) than other birds, so their feathers are soaked after a morning of fishing. Experts believe this difference is what actually helps cormorants hunt underwater more effectively.