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Posts Tagged ‘urban wildlife’

Recently, my Google-fu saved me from making the second-stupidest mistake a lepidopterologist can make (the stupidest, obviously, is confusing a butterfly and a moth). While looking for caterpillars of the cabbage white butterfly (for science), my labmates and I found these guys nomming what turns out to be a species of loosestrife:sawfly larvaSuperficially, it looks a bit like a cabbage white, but it has no business eating that plant! (Why’d you think they call them cabbage whites?!) But it’s actually not even close. It’s the larva of a relative of bees, wasps, and ants—a sawfly, probably Monostegia abdominalis, which specializes on loosestrife*. How can one tell the difference? Count the prolegs – the leg-like stubs behind the “real” legs, which are the first three pairs behind its head. If there are seven or more, it’s a sawfly; if there are five or fewer, it’s a caterpillar (usually). The beast in the picture has eight pairs if you count the anal prolegs, the pair on the last segment.

While their larvae look quite similar, sawflies and butterflies/moths grow up to be quite different. Sawflies burrow underground to pupate, and the pupae tend to look like weirdly frozen adults, while lepidopteran pupae look like blobs, sometimes wrapped in silk, and usually, but by no means exclusively, attached to a branch or other aboveground surface. Adult sawflies look quite wasplike, and they get their names from the females’ sawlike ovipositors, which are literally used to saw into plants so they can lay their eggs inside them.

I noticed many of the sawfly larvae curled up tightly on leaves or on the ground, as in the picture below. (It’s also done quite a number on that leaf! And when I checked back a week later, the patch of loosestrife was completely skeletonized.) They seemed to do this as a defensive posture, with one staying curled up for at least five minutes after I poked it. This behaviour apparently isn’t unique to M. abdominalis, as evidenced by this adorable picture.sawfly larva 2

*Unfortunately, they only seem to eat Lysimachia species, not the evil, despicable, nefarious purple loosestrife, which belongs to a different family.

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On overcast nights in Chicago, the sky is orange with light pollution. A few nights ago, the snow-covered roof of the gym was as orange as the clouds above it, but for the dozens of crows huddled in rows formed by the roof tiles, like sheet music lain on its side at the end of rehearsal.

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Friday morning, before the weather warmed up and the rain started, there was fog in the air and a foot of snow on the ground. On the lakefront, you could turn your back on the freeway and see only the ice-covered beach to one side, dark bare branches to the other, and, just barely, the silhouette of a jetty across the frozen bay. The nearer shore, built up with limestone blocks, was encased in eerie bluegrey icicles like a row of ghostly fangs. These dripped onto jagged, jumbled slabs of ice that bordered a dark and uninviting ring of slushy water—inhospitable except for the sewage pipe outlet, where a couple of mallards huddled.

The lake beyond this was a flat expanse of white all the way to the distant point where the ice blurred into the fog. But right in front of me, right in the middle of the little bay, was a black spot on the ice. A falcon—was it a falcon, or a hawk? Does it matter?—was tearing at a carcass, alone on the frozen lake. The gulls flying above seemed to give it a wide berth. A swath of feathers, and maybe blood too, but all colour had drained from this winter landscape, dusted the ice in an arc around the solitary bird; a few of them began to dance away from shore on the wind. The falcon, unruffled, focused on its prey.

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One thing you certainly don’t expect to see in a North American city known for its cold winters is a thriving population of parrots. Nonetheless, noisy flocks of them can be seen all over my neighbourhood. Monk parakeets, also called quaker parrots, have been breeding in parts of Chicago for at least 40 years.

How did they get here? Urban legends abound (one persistent story has them escaping from a crate at the airport, though their nests were first reported far from there), but all that’s known for sure is that they arrived via the pet trade. The long-tailed, greenish, pigeon-sized birds are native to southern South America, where they are agricultural pests, especially in fruit orchards.

Shockingly, these birds manage to stay through the Chicago winter. Though they’re native to the subtropics, and thus more tolerant of cold than the average parrot, they never encounter freezing temperatures in their original range. However, monk parakeets use their nests* year-round, and the massive structures (they breed communally, with several pairs building many-chambered nests that are often used for years) are well-insulated against the Windy City’s worst weather. But they rely on help from humans, too: they’re almost entirely dependent on backyard bird feeders in the winter.

Locals seem to have mixed feelings about the birds. Initially, the US Department of Agriculture was concerned that the parakeets would damage crops, as they do in their native range, and tried to remove them. They met with opposition from residents who liked the splash of tropical colour the birds provided. Though some birds were destroyed, the population rebounded, and so far the threat to crops hasn’t materialized.

However, other problems have: the parakeets began nesting on utility poles, posing a fire risk and causing occasional blackouts. The nests are removed, but the birds rebuild them in the same place. They also crowd out other birds at feeders, potentially threatening native birds**. On the other hand, some admire the parakeets’ adaptability and all-around pluck: they’re immigrants who help each other through tough times and start over in the face of setbacks. They’re not (yet?) a serious bioinvader, not like house sparrows or starlings. Perhaps we should learn to coexist.

But are they so benign? For now, maybe, but there are feral monk parakeet populations in New York City***, Spain, southern England, Japan, and many other places. A similar conflict between the perceived agricultural threats these birds pose and the feelings of local residents who welcome the birds simmers in many of these places. Like starlings, parrots are gregarious and extremely noisy—potentially another nuisance. And, dare I say it, perhaps climate change will allow further expansion of these populations. Just as we favour cute and fuzzy endangered species for our fundraising, are we also favouring the more ornamental invasives?

*In fact they’re the only species of parrot to build nests rather than use tree cavities.

**Granted, they’re mostly crowding out house sparrows, another, less-pretty, exotic species. In fact, in Brooklyn, New York, home to another feral population,  the parakeets are encouraged at Greenwood Cemetery because they drive out pigeons, whose guano damages historic buildings (apparently the parakeets’ guano is less caustic!).

***Fascinatingly, there’s also a probably-spurious escape-from-the-airport tale about the origin of the New York population.

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