How Many Deer are Too Many?
A topic often discussed in the general Penticton area but never addressed it seems, is the growing problem of urban deer. In Kaleden this topic comes up virtually anytime two or more people get together. And the problem is not confined to just our area; urban deer are a problem in many areas of BC and elsewhere in Canada and the US. A quick search of the internet brings up all sorts of articles on problem deer, from Kimberly BC, to Helena, MT to Connecticut and Alabama.
The problem is not just that deer are a real pest in peoples’ gardens, wiping out everything from tomatoes to roses to small trees in a few hours. Deer can be very aggressive and do attack both dogs and humans. Several of our neighbours here in Kaleden have sustained significant vet bills when their dogs were attacked and I’m talking about large dogs like Labs and such, not just small dogs. Increased densities of deer have been correlated with higher incidences of several diseases including Lyme disease and other tick borne diseases. In a study undertaken in Connecticut the incidence of Lyme disease was cut by 83% when the urban deer herd was culled. So far, Lyme disease does not appear to be an issue in the Okanagan.
Car – deer accidents increase as deer populations grow in urban areas although obviously not all accidents involving cars and deer occur in urban areas. Figures from ICBC and other sources show that about 19,500 animals (not just deer) are killed each year by cars in BC and the associated insurance claims total more than $35 million per year. Seeing a dead deer on the highway between Kaleden and Penticton is not unusual.
How many deer are too many? Several studies in the US have shown that deer populations exceeding 20 per sq. mile (7.7 per sq. km) can have a significant adverse impact on birds that nest on the ground or in shrubs and this same population density can change the composition and abundance of plant species within forest ecosystems. The City of Cranbrook has approved a limited cull of problem deer – their surveys determined that the deer population in Cranbrook was 3.7 per sq. km. The City of Kimberly has also been determining what to do about the deer problem – the density there is about 20 per sq. km. It is not easy determining the deer density - not only is there a problem in counting all the deer but the bigger problem is deciding what area to use. For instance, one might say that Kaleden, as an example, is a fairly large semi-rural area exceeding several sq. kilometers so seeing 10 or 15 deer shouldn’t be an issue. But when you consider that most orchards and vineyards have put up deer fences in the past few years, then the available land for the deer to browse has decreased dramatically. And, as the deer density has increased, the number of private houses putting up deer fences has also gone up significantly, so each year there are more deer living on less land.
The cause of the problem is at least twofold – urban areas have been expanding into rural areas but at least equally important, we have done away with the natural predators of deer – mainly cougars and coyotes. When I moved to Kaleden eight years ago we heard coyotes on a frequent basis – at least several times a week. About two years ago the coyotes disappeared for some reason and since then the deer population has significantly increased. Without predators or some other control, deer populations double about every two years and that certainly seems to be happening now.
Is there an effective alternative to culling? This issue has been studied extensively in Canada and the US to determine the effectiveness of alternatives such as trapping and relocation or using birth control. Both of these techniques have major drawbacks, with expense being significant. Trapping and relocation also caused significant animal deaths from the trauma associated with the process.
We could learn from Helena, Montana where a cull was carried out over three years from 2008 to 2010. As result, car-deer accidents decreased dramatically as did other deer complaints and the local food bank gained 12,000 lbs. of meat from the animals killed. In the Helena program, the deer were trapped and then killed with a bolt gun. In other jurisdictions, culls have been undertaken using bow hunters or sharpshooters.
The alternative to having a cull (and one will be necessary sooner or later) is to reintroduce cougars and coyotes into our environment. Since I can’t imagine that being very popular, a limited cull seems necessary. Yes, deer are a natural part of our environment; the problem is our environment is no longer natural!
The opinions expressed in this column are the author’s and not necessarily the position of the South Okanagan Naturalists’ Club.