[Marsymars]

> So the issue is that more northerly areas are getting much more variance in temperature and lacking long deep consistent cold periods.

It impacts the population, but even a couple solid weeks of -20C weather doesn't seem to be enough to eradicate them.

[b112]

Ticks have always been around Ottawa, and even in 2011? I recall -40C for well over a week, and obviously cold temps around that week.

Insects lay eggs, and also go dormant under fallen leaves typically. The snow + leaves insulates them, it's how live insects survive the winter.

If you watch robins in the spring, before the ground thaws, you'll see them flipping over leaves. They're eating loads of insects hiding, most still torpid from the cold.

-40C isn't a problem for ticks to live through in this way.

In terms of population, everything follows predator/prey cycles. Nothing is static. It's normal for populations to "explode", eventually predators will grow in numbers too.

I see it with noseeums here, and dragonflies. There are almost no noseeums this year, but loads of dragonflies, which means the dragonfly population will collapse, and soon (couple of years) the noseemums will be relentless. But then the dragonflies will grow in numbers, with plentiful food, and the cycle will repeat.

It's natural.

Global warming may shift habitats, but these ticks are normally here. They're not new.

[chairmansteve]

If there was more diversity in predators and prey, the population cycles would have smaller amplitudes. The large swings are often symptoms of a collapsing ecosystem.

[cmrdporcupine]

The lowest recorded temperature in Ottawa in the last 40 years was -33.1c in 1996. It hasn't been down to -40 since like 1911.

You might be recalling wind chill temperatures, which would not be relevant here. They're subjective perceived temperatures for hairless apes.

However it does occasionally get to (real) -40C ish in Edmonton area, and they now have populations of blacklegged ticks. But very small populations.

Like I said above, the issue is not the absolute lows or highs, it's durations of cold, which impact their ability to recover and produce large quantities of eggs in the spring. This was literally in an article I was reading about ticks the other day, don't make me hunt for it.

Black legged ticks are not new to Ontario, but they absolutely are to places like central Alberta. And the Lone Star tick is moving north for similar reasons and will be established here in Ontario shortly as well.

[b112]

I live in the Ottawa region, and it was indeed -40C for a week where I live. My Jetta screaming "warning extreme cold!" at start, and the kitchen window thermometer I have doubly validate that.

I'm also 20 minutes to downtown, outside of rush hour, so I stand by the ease of saying "Ottawa".

No you don't get my address, but temperatures in cities and at airports are warmer than rural areas in winter. Where I live, I'm also higher up by several hundred feet, and it all matters. I don't blame you for checking, but the city of Ottawa encompasses a lot of rural land.

It can rain torrents in part of southern Ottawa, but Ottawa weather stations could remain dry.

My point about snow and leaves, is that if there is snow cover, they're completely happy, insulated, nestled in the leaves.

I don't doubt you read an article, and from a reputable source, I just don't buy their assertions. Lack of snow cover would be a bigger predictor than overall temp.

[cmrdporcupine]

Dude, weather stations record actual temperatures both in and outside the city. Environment Canada peppers the whole province with them. There's nowhere in southern or eastern Ontario that gets as cold as -40C. It simply doesn't happen. -35C is the lower bound and that is extreme.

I know this because I farm and grow grapes and have meticulously poured over weather charts for the whole province. (Survival cut off for hybrid and wild grapes is really around -32C or so. Vinifera... maybe -20C)