the bad news about deer
douglas todd: much-loved deer are more plentiful in b.c. than in the 1800s. trouble is they're devouring forest plants once central to indigenous food supply. birds suffer, too. there are solutions.
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deer are undeniably cute. so columnist douglas todd doesn’t feel great analyzing how to reduce their populations.
b.c. wildlife federation
black-tailed deer are a wonder to behold whenever they are spotted in southwest b.c., from the north shore mountains to the gulf islands and victoria, where hundreds nonchalantly roam neighbourhood lawns. they are a west coast mammal that inspire many people to show greater respect for wildlife and the natural world. they have an appearance of calm, curious pride
deer are undeniably cute.
so it doesn’t feel great to be the bearer of bad news about them.
still, like many who walk or hike local wilderness, i have begun to notice our towering forests, while always impressive, often seem at ground level to be kind of monotonous. the range of plants seems limited on the forest floor, even to my very amateur eye.
i’ve since learned that this is not the way our forests were more than a century ago.
indigenous people in b.c. once feasted on a host of edible plants from the forest — particularly the bulbs of camas lilies and on honeysuckle. and there were bushes thick with blackberries and salmonberries.
for a century many believed that the dearth of these valuable plants was caused almost entirely by such things as human encroachment, herbicides and invasive species, such as grasses and thistles that deer and everyone else find inedible.
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but in recent years researchers at the university of b.c. and elsewhere have found forest terrain in some regions has become more barren mainly because they have too many deer. far more than they did in the past.
that’s for two reasons. one is that settlers in the late 1800s killed many of the animal predators that relied on deer, like cougars and wolves. some islands in the salish sea no longer have natural deer predators.
the second reason is that, in the 1970s, the hunting of deer was banned or severely restricted in many parts of southwestern b.c. (as well as in other regions, such as ontario).
the push for severe hunting restrictions grew in large part out of the public’s emotional attachment to the wide-eyed deer and from conflicts over the ethics of killing animals in the wild.
many scientists, conservationists and ethnobiologists, however, have been among those asking nature lovers to take a more empirical approach to rising deer populations.
specialists point to how the removal of large predators in ontario and the eastern u.s. over the past half century has led to an explosion in hungry white-tailed deer — and a 50 per cent reduction in forest plant species.
ubc professors such as peter arcese, emily gonzalez and tara martin and the university of victoria’s nancy turner have been collaborating with indigenous people to facilitate the return of native plant species.
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one of their key findings is that the native plants that indigenous people once ate start to return when deer populations are reduced, either by the return of wolves, by creating fenced enclosures or by allowing some hunting.
there are efforts in b.c. and elsewhere to relocate deer or inject them with birth control vaccines, like in parts of greater victoria, where scores of deer eat garden flowers and can be a road hazard. but those programs can be expensive and, sometimes, limited in effectiveness.
whatever method ends up being used, gonzalez, arcese and others have found through experiments that there is a simple formula for the optimum density of deer: a ratio of one deer for every square kilometre of natural terrain allows natural plant species to return, often at a phenomenal rate.
the bulbs of camas flowers were once a key source of starch for indigenous people in b.c. but camas and berry bushes are among the forest plants devastated by growing deer populations.
luke mattson
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in an experiment on salt spring island over three years, the ubc team created 56 open and enclosed plots of land, on which they planted such things as camas lilies, the bulbs of which were a major source of starch to indigenous people.
what they discovered is that the camas bulbs planted in the plots protected from deer became three times larger than those in unfenced plots. other native plant species, such as harvest brodea, became 12 times more more robust.
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to the surprise of some, an optimal ratio of deer to terrain also helps to restore bird populations in a dramatic way.
in an extensive study of 18 islands in the salish sea, including south of the border, a team of researchers found rufous hummingbirds were nine times more abundant on islands with few deer then on islands with many deer. spotted towhees were 25 times more prevalent and native song birds were four times more plentiful.
researchers found rufous hummingbirds were nine times more abundant on b.c. islands with few deer versus many deer.
these birds and others became more plentiful when deer densities declined because deer can voraciously chew up so-called “understory plants,” which are small trees, shrubs and vines that grow in the shade beneath tree canopy and on which native birds both feed and nest.
cutting deer populations is not necessarily a pleasant topic, especially when it comes to the subject of hunting. divisive conflicts have arisen, for instance, over the plan by parks canada and first nations to cull some of the almost 1,000 deer on small sidney island, near victoria.
nevertheless, as the data now show, deer populations decline and plant species return when even a modest amount of hunting is permitted, as is increasingly happening on a variety of gulf island islands and elsewhere.
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it’s crucial to face up to the reality of an overpopulation of deer in some regions if we want to return many of b.c.’s southwest forests to something close to their original vegetative profuseness, say experts. not only to revive some ancient food sources, but to benefit native birds.
ultimately, failing to reduce overabundant deer populations may add many native shrubs, such as ocean spray and orange honeysuckle, to threatened species lists, said arcese.
“failing to act to reduce deer populations on islands where historically abundant species are currently declining or (being destroyed) is a decision to favour one species, the black-tailed deer, over many others that are also native to our region and valued by many humans.”
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