The ‘Missing’ Deer

If you follow the news or social media in New Brunswick you might have the impression that white-tailed deer are vanishing from this Province. These ‘disappearing deer’ stories are usually associated with condemnations of current and past forest management policies in New Brunswick. Although management of Crown forest lands in New Brunswick might be far from optimal, the evidence that those practices are having a decisive impact on deer populations is mixed. Data available from the New Brunswick Department of Natural Resources (DNR) and published by the CBC show that deer populations in the 1970s are similar to those that we have seen in more recent years:

Note that the title on the CBC story referred to above is ‘New Brunswick deer herd down 70% in 30 years, DNR numbers show’; but it could just as well have been titled ‘Deer populations revert to 1970s levels, DNR numbers show’. [Update: The blue line in the chart above uses data supplied in the CBC story. The green line (Herd Size B) in the above chart represents updated pre-hunt population numbers provided in the Big Game summaries from the New Brunswick Department of Natural Resources. The latter is based on a model relying on various inputs – the chart has been updated to use 2021 model calculations.]

If you are interested in forest management, the 2008 Erdle Report provides a comprehensive review of alternative forestry management policies. Timber harvests from Crown land in New Brunswick are considered to be at or near maximum sustainable levels, despite intensive silviculture operations.


2. The White-tail Deer in New Brunswick

3. Changes in Habitat

4. Habitat Management

An interesting observation from the above chart is that, while purchase of deer licenses increased as deer populations jumped upwards during late 70s and into the 1980s, the proportionate increase in licenses was far less. That means that while there were more folks hunting, there were many more deer to hunt. Hunters likely saw more deer then, and had more success. Young folks hunting then would be today’s ‘boomers; many residents might not be aware of historical fluctuations in deer populations, and might thus be amenable to suggestions that particular forestry policies, for example, are responsible the ‘decline’.

It should also be noted that the deer population estimates are, in part, based on deer harvest data. That means there is some confounding in the data – we should not read to much into them, and use the data for trends and not much else. Data from earlier decades of the 1900s are hard to find; Wright reported a deer harvest of about 22,000 deer in 1950, and noted that that harvest level represented a 52% increase over that of 20 years previous. A harvest of 22,000 deer would, on the basis of the above graph, suggest a deer population of about 100,000. In other words, the early 1950s likely saw a peak in deer populations (considered as unsustainable by Wright, and similar to what was seen in Nova Scotia at that time – see below), followed by a crash, then another increase from the late 1970s through the 1980s.

The main take-away from the above graph is that populations of white-tailed deer have fluctuated tremendously over the past few decades, peaking in the mid 1980s at levels over three times the current population. So, the real question in my mind is, why are deer populations fluctuating so much? Why do they go up and down to such an extent?

2. The White-tail Deer in New Brunswick

First, let’s look at some historical perspective. The white-tailed deer is, for most of the Province, an invasive species; prior to the 1800s, it was not particularly common in New Brunswick (Wright 1951). Likely, deer were confined to the more southerly parts of the Province and probably not widespread. Cold winters have probably restricted white-tailed deer populations in this part of northeastern North America  since 1000 AD or so. Reports from early European settlers, such as Nicolas Denys, refer to First Nations people hunting moose, beaver and bear, but not deer. From an article published at the apparently defunct Elements NB website (you can still find it via the Internet Archive), Stephen Clayden noted:

Although caribou numbers in northeastern North America were already much reduced by the late 1800s from those of previous centuries, the ultimate extinction of the species in New Brunswick, Nova Scotia, and adjoining mainland regions appears to have coincided with the influx and explosive population growth of white-tailed deer. Deer were rare in the Maritimes in the early 1600s, and remained so for most of the next three hundred years. A scarcity of immature forest cover and clearings, their principal habitat, was probably the main factor limiting expansion of the white-tail’s range. But as deer spread northward in the wake of European settlement, both caribou and moose populations were affected. In areas with a high density of deer, many moose succumbed to a mysterious sickness. However, while moose and deer established a somewhat precarious coexistence, caribou perished.”

In other words, the old-growth mature forest habitat that dominated New Brunswick until European settlers began clearing the land was NOT habitat that favoured white-tailed deer. Deer prefer the more open habitat of either natural clearings (along rivers, flood plains, mixed prairie/woodlands, etc) or clearings created by fire or farming – provided that there are wooded areas nearby where they can hide from predators and seek shelter from harsh weather. Clearings support the small herbaceous perennials, grasses and grains that provide excellent deer food. First Nations peoples cleared land for farming and also used fire as a woodland management technique (see Mann, Charles. 2005. 1491: New Revelations of the Americas Before Columbus). As Europeans settlers cleared more and more land during the 1800s and early 1900s, the deer population in New Brunswick grew markedly, and the caribou and moose that dominated the old growth forest declined. Again, from Clayden:

A telling glimpse of the reversal in fortunes of caribou and deer in New Brunswick is contained in a reminiscence by guide and outfitter Bert Moore (1883-1972), published in the Winter 1996-1997 issue of the magazine New Brunswick Tree and Forest: “In 1900,” wrote Moore, “there were very few deer in the Tobique–Nepisiguit country, but caribou were there in great numbers.” He attributed the precipitous subsequent decline of the caribou to a rapid increase in the deer population. This, he assumed, led to competition between the two species for a limited food supply, and to the caribou, now supposedly under-nourished and weakened, becoming more susceptible to disease.”

Several summers ago, while exploring one of the large coastal peatlands in Gros Morne National Park in western Newfoundland, I was struck by the signs of intensive caribou grazing and trampling of the ground-inhabiting lichens. It occurred to me for the first time that the similar lichen carpets in many of New Brunswick’s drier peat bogs, especially those of the east and northeast coasts, are unusually pristine. Caribou must have frequented these areas up to the late 1800s. They are unlikely to do so again, however, on this side of the next Ice Age. Unless, of course, we allow the province to revert to old-growth wilderness and thereby exclude the beautiful but fatal white-tail …

Deer, by the way, were also uncommon in our sister Province, Nova Scotia, until the late 1890s and early 1900s. But, according to Patton (1991), by the 1950s “deer were far more plentiful [in Nova Scotia] than they had ever been before. Hunters and deer watchers alike were treated to a new and memorable experience. There probably were deer in more people’s back yards. More of our population lived in the country on small farms with small pastures, firewood lots behind the house, gardens and crop fields. The small farms provided the best deer habitat possible. Deer concentrated around those farms and ‘everybody saw deer’. Hunters who did live in cities or towns went to the country to hunt but fewer roads and a lack of ATV’s and other rapid off-road vehicles meant those hunters went to the small farm areas where the roads led. They hunted the concentrated deer and were successful. At the peak there were about 63,000 hunters sharing a kill of 46,000 deer. About three out of four hunters got a deer.” That situation did not last – deer harvests fell to about 20,000 per year during the 60s and 70s, then rebounded to over 66,000 in 1985, only to fall to about 16,000 in 1990.

These historical records indicate that there were relatively few deer in New Brunswick until the last couple of hundred years, then deer populations increased significantly as farmers cleared land and settlements grew. But why the ups and downs in populations since then? There can be many explanations. A series of very cold winters with deep snow will reduce deer overwintering survival; mild winters with little snow may promote survival; over-hunting may place too much pressure on populations; etc. Unregulated hunting, in fact, nearly wiped out deer in much of the United States by the early 1900s

“…unregulated year-round harvests of deer, often aided by packs of dogs, night hunting with fire torches, or hunting from boats, coupled with extensive habitat losses during the mid to late 1800s, led to a dramatic decrease in the number of deer…..By the end of the nineteenth century, an estimated 300,000–500,000 deer remained in North America (Downing 1987). Remnant deer populations were small, isolated, and typically confined to mountainous areas, coastal marshes and swamps, and river bottoms that were inaccessible to hunters.

3. Changes in Habitat

Habitat changes in New Brunswick over the past 50-60 years have also been significant. In the 1930s, farming in New Brunswick was near its peak:

Early in the last century, farmers in the province worked on a large number of small farms. In 1931 there were 34,025 farms, with an average of 122 acres per farm. By 2006, the number had decreased to 2,776 farms, with an average of 352 acres per farm. However, the total farm area in New Brunswick had gone down, from 4.2 million acres in 1931 to 976,629 acres in 2006.”

That’s a decline in farmed land of over 70%.

Much of that land has reverted to forest – either managed or unmanaged woodlots. Some of that farmland has been converted to suburban development, and some of those suburbs (low density housing on large wooded lots) provide reasonable deer habitat. But many suburbs in large towns and cities do not provide good deer habitat – there is insufficient tree cover, food, or shelter for deer. As forest replaced what was once farmland, deer were deprived of the herbaceous plants and grasses they feed upon. Deer populations thus may fall in extensively re-forested areas and may remain healthy only in ‘one-acre lot’ suburbs, or in areas where there are natural open spaces. Ironically, deer populations have likely declined in many rural areas of the province as farms were abandoned and converted to woodland. We’ve gone from being a Province where a large proportion of residents were both employed and living in rural areas to one where most rural residents are really suburbanites commuting to urban areas for work.

I’d also note here that many of these farms in the 1950s through to the 1970s would have received multiple pesticide applications – not just herbicides, but a wide range of insecticides (DDT, for example) and fungicides. Regulatory controls on pesticide use were far less stringent than today and many of those products were eventually removed from the marketplace because of toxicity to humans and/or wildlife. Given the laxer regulations and poorer knowledge base of those days, it is likely that fertilizer run-off and soil erosion were common problems. Deer populations appear to have done pretty well, however, and that might suggest habitat and weather patterns have greater impacts on deer populations than frequent exposure to the pesticides being used on farms in New Brunswick during those years. With the decline in farmed land, it is likely that the pesticide ‘load’ on the New Brunswick environment has also declined significantly in recent decades.

Of course, these types of massive land use changes (moving from old growth forests to farmed land, then back into forest cover) affect not only deer, but many other wildlife species. Birds that require dense forest cover might decline as land is cleared for farming, while birds that prefer open spaces might increase in abundance. As farms are abandoned and revert to forest, some bird species would be favoured, others disadvantaged. Under such circumstances, it’s problematic to determine what bird species distribution is ‘abnormal’. Changes in biodiversity are not necessarily good or bad, it all depends upon the circumstances. More important, perhaps, is protecting species that are threatened with extinction by such changes.

4. Habitat Management

And what about clear-cutting? If you have a large area of woodland where there are few open spaces to provide good habitat for deer, then clear-cuts can provide those habitats. Absent farmland then, clear-cuts can be essential to maintaining large deer populations in forested areas. The huge growth in deer populations in the late 1970s and 1980s (when the deer herd increased to over three times the 1970 population) can, at least in part, be attributed to the spruce budworm epidemics of the 1950s – 1970s. (for some interesting comments on spray programs to control budworm in New Brunswick, see here – “By 1952, large patches of forest in the northern part of the province were grey, i.e., they had been completely denuded”). Those epidemics killed millions of conifers and created natural clear-cuts of a sort, allowing light to reach the lower levels of the canopy and thereby promoting growth of herbaceous plants upon which deer browse. Natural regeneration of such stands can also be adversely affected by deer, if deciduous forests are the desired outcome.

In addition, many budworm-killed trees were no doubt mechanically harvested in order to save the wood from decay or prepare land for re-stocking. Those actions also created large clear-cuts. Manual replanting with conifer species that the forest industry desires takes place in following years. Competition with undesirable species is reduced by either manual removal of deciduous plants, or by use of herbicides. It is only economical to apply herbicides a limited number of times (once per year or less during early years of regeneration) to clear-cuts. The role of herbicide application is not to eliminate competitors but to suppress the growth of competing plants such that the planted conifer seedlings have a growth advantage. These products are not particularly persistent and herbicidal activity is short-lived. Thus, even with herbicide application, there is likely sufficient food for deer.  In order for herbicide application or manual brush removal to significantly affect deer food supply, the deer population would need to be at or near the carrying capacity of the clear-cut – that seems unlikely (and undesirable if your goal is to promote hardwoods). There are also claims that one particular herbicide, glyphosate, must be responsible for antlered female deer found in New Brunswick – it seems not to have occurred to folks to ask about the frequency of antlered does in other parts of North America. They might be surprised to learn that as many as 1 in 900 female white-tailed deer may have antlers. How likely is it that deer populations are now being suppressed by one herbicide applied infrequently to a small part of the Province when those deer were not apparently affected by widespread pesticide applications to farms in previous decades?

Herbicide and pesticide formulations may also contain surfactants/adjuvants, such as polyethoxylated tallow amines (POEA). Although high concentrations of surfactants can be toxic to aquatic organisms, there’s no evidence that in real-world situations they cause significant damage. Surfactants/adjuvants are widely used in pesticide formulations, not just glyphosate products. One of their benefits is that they often reduce the amount of pesticide product required per hectare. Note that some formulations of ‘organic’ fungicides may also contain, or be applied with, surfactants.

In any case, it seems reasonable to conclude that the clear-cutting that followed the budworm epidemics of the 1950s, 60s and 70s provided, via promotion of large populations of herbaceous plants and grasses, a large increase in good deer habitat, and this likely contributed to the boom in deer populations that began in the mid-1970s. That boom is reflected in the sharp upward direction of the population curve in the above graph. Clear-cuts are generally thought to provide good browse conditions for white-tailed deer.

By contrast, as those planted conifers grew and matured, deer food declined and deer populations eventually fell back to their previous levels of the early 1970s. Those large deer herds also no doubt helped encourage growth of coyote populations, as they prey on deer. Moreover, by the 1990s, farmland acreage had collapsed. Consequently, the population distribution of deer has changed from the early 1970s (there are fewer ‘rural’ deer and more ‘suburban’ deer) while the total population is now at about the same level as it was then. In addition, deer that reside close to ‘one-acre lot’ rural suburbs are often ‘out-of-bounds’ to hunters – that further reduces the hunter’s success rate, relative to the total population of deer. In other words, a smaller percentage of the total deer population is accessible to hunters than was the case prior to the collapse of farming.

Clear-cuts are not always a positive for deer, however. For example, the maintenance of winter deer yards are vital to protect deer during harsh winters. Conifer stands in such yards tend to have lower snow depths than open or deciduous stands; this makes it less difficult for deer to move about. Over-harvesting of conifers in such locations (and thus creation of clear-cuts) would likely be harmful to deer populations. Possibly, the spruce budworm outbreak in northern NB resulted in loss of deer over-wintering habitat. Assessments of whether deer yards have recovered or need better management should be undertaken in a manner independent of wood fibre production concerns. Proper deer herd management would include protection of conifer and mixed deciduous/conifer stands in deer wintering yards. Not all clear-cuts have the same impact on deer.

If we compare New Brunswick and Nova Scotia deer harvest (kill) data (taken from sources cited above), we can see similar trends in both provinces. This suggests common trends in population fluctuations in these adjoining provinces:

Bottom line: while weather patterns and hunting regulations influence deer populations, a major determinant is habitat. White-tailed deer were not common in the Maritimes in the 1700 and 1800s but a population explosion took place as European settlers created suitable deer habitat by clearing land for farms and towns. More recently, the loss of farmland and its conversion to forest has greatly decreased deer habitat in the rural areas. The nature of the forest may have changed from old-growth forest dominated by a mix of deciduous trees and conifers to a managed forest of relatively young conifers, but, from the perspective of white-tailed deer, the New Brunswick forest is just not that attractive. Given the role that the deer play with respect to Lyme disease and other zoonotic diseases, perhaps that is not entirely a bad thing.


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