Archive

winter

My brother sent me a photo of his woodpile – Jan. 26, 2019 – see his photo in the bottom line of photos. He lives on the French River, south of Sudbury. Lots of snow there, more on the way. The other photos are some I’ve taken over the years; bottom right shows a very poor condition deer after a long, cold snowy winter, same as the large photo in the top left.

With the recent spate of snow and cold, I looked at an article I wrote for Ontario Out of Doors magazine in late 2017 and decided to post it on my blog. So although it’s a year old, the information remains relevant. Given that snow this winter has come late, deer might still have a good go of getting through the winter, but, maybe not. Rule of thumb says 50 cm of snow on the ground for over 50 consecutive days, deer mortality from the rigors of winter spikes. Which means it all depends on how long winter lingers. Last winter, it lingered, and deer numbers in much of northern Ontario, especially in the north-west, where I live, took a hit. Again. Over the past 6 or 7 years, there have been several hits.

I don’t think this year in the north-west will be particularly hard on deer, but weather is only one factor, as wolves are licking up the remaining pockets of deer. Outside of Thunder Bay and the smaller cities – all of which now have urban deer herds – deer are not doing well. I don’t think deer will do well until we get another spruce budworm outbreak, which is still a few years off (see my posts on lichens for an explanation and the relationship between deer numbers and arboreal lichens in northern forests).

BTW, I grew up in Sudbury and there were very few deer there in my childhood. There still is not a lot. Most years, the Sudbury area gets a lot of snow. Lots of snow during most years does not make for a healthy herd of deer.

Hope you like the article.

Snow, the Silent Killer

Pat Karns, a respected and well-liked biologist stationed in Minnesota, years ago called winter ‘the Grim Reaper’. He made the case that cold, snowy winters are a primary driver behind deer population fluctuations in the northern forested areas of the USA and Canada. When it was cold and snowy and the winter long, deer might die in droves. Karns made those observations decades ago, but it’s still true today. Deer – and other birds and animals – have evolved to cope with cold and snow, but a severe winter will have consequences. While there are management options available to help wildlife populations get through winter, there’s only so much that can be done. Snow can be a deadly killer, and Ontario gets snow. Some years, Ontario gets a lot of snow.

Wildlife managers in provinces and states where snow and cold are prominent aspects of the weather calculate estimates of winter severity, including input to models used to manage the deer harvest. For example, winter severity is included in the annual calculation of the number of antlerless deer tags and additional seals issued.

Scientists, biologists and other researchers have a long history of looking at the effects of winter on wildlife. Americans like Louis Verm and John Ozoga were winter and snow severity pioneers, but Ontarians like Robin Hepburn and Dennis Voight were also instrumental in devising methods that gave us winter severity indices that agencies like the MNRF use to assess winters impact. Dependent upon the system used, deer managers generally categorize winters as mild, moderate or severe. Sometimes very bad winters are called ‘extreme’.

Whatever system is used, the value generated to categorize winter severity is typically a combination of snow, temperature and time. In Ontario, the system commonly used is called the Snow Depth Index (SDI). To calculate SDI, a snow course – a forested site where snow depth is measured in cm at 10 stations over the duration of the winter – must be maintained. An SDI is obtained from each snow course from the weekly, average, snow depth measurement; the over-winter SDI is the cumulative total of the weekly average snow depth readings.

Ontario has maintained snow courses since 1952. In most years, dozens of snow courses are run, mostly across the deer range of northern and southern Ontario.

To assess winter severity, MNRF usually looks at a number of snow courses in a particular area. When averaged together, a value of <590 is indicative of a mild winter; 591-760 is moderate and >760 is severe. Severity can vary across the province.

Once a winter has been categorized, values pertaining to recruitment and mortality can be estimated. In Ontario, SDI suggests >40% of the fawns would be lost at birth following a severe winter.

During a severe winter, deer can also die of starvation, exhaustion or succumb to high levels of predation and might result in a loss of ½ the herd. A series of severe winters can reduce deer numbers by as much as 80%.

Mark Ryckman, Senior Wildlife Biologist with OFAH, said “Parts of Ontario experienced back-to-back severe winters beginning in December 2013. We’re just now starting to see deer populations bounce back.”

Other winter severity indices that have been used in Ontario include the Passmore Snow Severity Index and the Ontario Winter Severity Index. In the Great Lake States region, Michigan, Wisconsin and Minnesota each use unique, but similar winter severity indices; all indices are based on field measurements of snow and temperature over time.

SDI is a simple yet effective way to measure winter severity despite the fact it doesn’t measure snow crusting (and whether deer can walk on or break through it) or use any measures of temperature or wind. These factors can be of note – it’s obvious deer will benefit by  walking on snow rather than breaking through or wading through it to get to food – and a pleasant winter day of mild temperatures, sun and no wind is no doubt preferable to overcast, cold and windy weather; all factors some other indices incorporate.

The reason SDi is so effective is that while it focuses on snow, it indirectly is incorporates other factors. For one, if there’s not much snow on the ground, cold isn’t a big factor, as deer can easily access food. If there is a lot of snow, but it doesn’t cover the ground for months on end, most deer – and their unborn fawns – can survive. But for lots of snow to stick around, there needs to be extended periods of cold (that keeps snow from melting) and extended snow cover keeps deer off their best foods (generally small plants in fields and on the forest floor), with or without a crust. So the bottom line is that a long period of more or less continuous snow cover is indicative the winter was long, cold and snowy.

SDI provides information that’s invaluable to Ontario’s deer managers, but it can also be used to assess the impacts of winter on other species, including moose and turkeys.  Although moose are huge, they do run into trouble when snow depths of around 100 cm exist for several weeks, which isn’t that unusual in the vicinity of the Clay Belt and other areas north of Lake Superior. In the south, turkeys kept from foraging in open fields or the forest floor for long periods because of continuous snow cover can experience high levels of mortality.

Snow. It really is the silent killer.

Different species avoid bad weather – winter – in different ways.

It’s easy to see why the global warming issue is so big. It’s all about the weather, and every last one of us is affected by the weather.  Despite hopes, beliefs and hard effort to control the weather, the best way to minimize harm that might come to you because of bad weather is to use protection: a rain coat as opposed to a rain dance.

Our obsession with the weather goes back a long way; for example, there is a lot of talk of weather – and controlling it – in the Bible. While I haven’t done an extensive check, I’m sure weather plays a big part in all religions and cultures. Simply put, we are weather dependents and, using again a quote from a country song, “It’s always been that way.”

In Canada, winter weather is usually the worst.  The majority of birds in this country migrate south, en-masse, to avoid winter weather. Some animals also move to areas with better winter conditions, but many others have evolved to find a good spot to lie down and go to sleep for the winter. They only wake up when the weather improves. The rest have to face winter weather head-on and find a way to cope with the cold and snow and the storms.  It’s a tough go to try and survive a winter when, for months on end, the food supply never increases, only dwindles; temperatures are constantly below freezing and everything is covered with snow.

Because of the significant impacts winter weather has on wildlife, wildlifers use a variety of techniques, including indices, to assess the impact of winter on particular types of wildlife. In states and provinces where winters regularly decimate white-tailed deer populations, winter severity indexes were developed that generate numbers that are used to categorize the severity of a winter and provide estimates as to the number of deer that likely perished over-winter. The categories are generally “Mild, Moderate and Severe”; the higher the number, the more severe the winter.

The winter that just passed in the area where I live, was long, windy, cold and snowy.  The Ontario Ministry of Natural Resources and Forestry, which has as one of its responsibilities the management of deer, categorized the winter as “Severe” in the district where I live. There’s no doubt it was a hard winter on the local herds of white-tailed deer.

Still, some deer survived. I’ve seen a few around.

A few years ago, deer were common, sometimes abundant, hundreds of kilometers north of where they’re common today. But a series of hard winters, and some other factors, pretty much rubbed them out. I recently authored a paper with a colleague that showed how deer (and moose) populations have fluctuated in this area over the past many decades; we concluded that landscape level perturbations (e.g., fire) are the main reasons these populations fluctuate wildly over time; and of course, much of these perturbations and related events are weather related. You can read the paper here: http://alcesjournal.org/index.php/alces/article/view/227

Animals cope with the elements by living in habitats that provide them with the essentials of life, namely food and cover. If you are in the business of wildlife management in North America, part of the job is likely addressing habitat management issues. There’s still a strong belief by biologists that habitat is often, if not usually, the key factor affecting the survival of a species. If habitat is suitable, and there’s enough of it, most animal populations should do okay. Habitat isn’t easy to describe, and it’s used differently by different animals.

A feature of good habitat is the ability to provide relief from the weather. Deer often congregate in specific areas, usually called a ‘yard’, where both food and cover are available.

Unfortunately, a lot of the time, effort and money that could be spent on trying to do a good job of wildlife habitat management is, I think, being spent on trying to manage the weather. It’s a real flip-flop, and not without consequences. Spending billions on trying to manage the weather (e.g., climate change) is increasingly being viewed with much scepticism. Some say it’s environmentalism. I think it’s mostly virtue signaling – spending lots of money being ‘green’, without much in the way of actual, tangible results.

Personally, I can think better ways to spend money on conservation of wildlife than squandering millions (billions?) on windmills that are notorious bird and bat killers and don’t really make a dent in reducing CO2 emissions.

However, priorities do differ amongst jurisdictions and on-the-ground habitat management programs do exist in some places. In some – the state of Michigan comes to mind – they can be surprisingly robust. Elsewhere they may be close to non-existent. If sound habitat management programs aren’t in place and funded in the area where you live, there’s a good chance many species of wildlife near you are floundering.

Habitat management is not the be-all and end all when it comes to looking after wildlife, but there’s little doubt good habitat, and habitat management policies, is a whole lot better than poor habitat and a focus on reducing our ‘carbon footprint ’.

I’ll be addressing habitat issues a bit more thoroughly in future postings.

cards-16

Spring is in the air. Yesterday was a very nice, late winter’s day (actually, the 1st day of spring), although by evening the wind was howling, the temperature was plummeting and snowflakes were being blown around. But earlier, it had been a nice day.

It’s been a weird winter. For the first time since I’ve lived here – over 35 years – most of the winter saw the snow with a hard crust, the kind you can walk on. In fact, I’ve looked at snow records for this area that go back to 1955 and see no indication of a winter with similar snow conditions.

I don’t know how that’s going to play out for the local wildlife, but I’m inclined to think not too badly. During our daily walks with our dogs, we are regularly seeing snowshoe hares, ruffed grouse and deer. On the other hand, there aren’t near as many hares as there were earlier, a testament I’m sure to the hunting success of the lynx, marten and fox, the tracks of which we regularly encounter, but seldom see.

And while there remains a small herd of about 7 deer on our property, we note they are regularly harassed by wolves. We haven’t seen any wolves of late, but every few days their tracks show us they are still nearby. Neighbors have told us the wolves have killed at least a few deer in the past weeks near them. It’s a concern that in our drives away from town, we see few – very few – deer tracks. No signs of moose at all.

With so little big game, it’s hard to see that wolves didn’t suffer. Wolves can’t thrive on a diet of mice and hares. Research has shown that each wolf needs about one adult deer every 20 days over the course of winter just to survive. But wolves are, if anything, survivalists. I admit I’m amazed there are as many wolves as there are. When the deer population crashed four winters ago, I would have thought the wolf population would have followed suit no more than a year or two later.  Still, it’s only a matter of time.

Despite the recent melting, there’s still a covering of snow on the ground and it’s still dense enough to support one’s weight. Like I said, yesterday was nice; it was sunny for most of the day and the temperature got to about +80 C.  Last night it dipped to -150 C and isn’t supposed to get above the melting point again for another couple of days.  There’s a lot of ice on the local lakes – more than two feet on the lake where Lil and I went fishing yesterday, so ice-free days are still off a bit (yes, we did catch some fish. Tasty speckled trout, as a matter of fact).

On a gloomy note, I received a report last week on the state of chronic wasting disease (CWD) in North America, the prion, brain-wasting disease now found across wide swaths of North America that’s killing off white-tailed deer, mule deer, elk and even moose. CWD continues to spread and once established in an area, seems to be impossible to eliminate. Once an animal is infected, death always follows. Some of the models being used to predict the outcome of this plague suggest that local, perhaps widespread extinctions are possible, if not probable.

What a mess.

Oh well, it’s spring! No time to get depressed. Plenty of time for that later.