Gabriel McMurren, Bird Advocates Contributor

My home of Eastern Ontario is dotted with innumerable lakes and rivers, among them the most picturesque, biodiverse places to birdwatch in the country. There may be no species of bird, however, that represents this distinctive ecozone quite as well — even for non-birders — as the Double-crested Cormorant. Once highly endangered in the era of DDT, these birds have rebounded significantly throughout their North American range; indeed, I have seen many a colony with dozens of birds to a single rock stack.

In Ontario at least, the cormorant’s recovery was swift (if not complete); however, there is an increasingly worrying flip side to this conservation success story. Like cormorants, humans enjoy living, swimming, and hunting by the water, and calls to the provincial government to establish a cormorant cull became more frequent as the birds rebounded. Finally, in 2019, the Progressive Conservative government added the Double-crested Cormorant to the provincial list of game birds, with bag limits of 50 birds per day and a hunting season from March 15 to December 31.

While the backlash from the natural community prompted the government to amend the bill (the first day of hunting season was pushed back to September 15, and daily bag limits reduced to 15 birds), they did not remove the bill altogether. In my view, there simply is not enough scientific evidence for this drastic bill, and the provincial government should instead consider less drastic means of population control (if any at all).

But why control populations in this way? Here are the most common reasons given, in no particular order.
1) Cormorants are harmful to sport fish populations,
2) The acids in cormorant guano kill trees, harming the natural environment,
3) Cormorants are a non-native species that aggressively push out other species,
4) There are too many birds for the available space,
5) “Concerns about aesthetics” (actual excerpt from the Environmental Registry of Ontario)

After reading multiple reports, articles, newsletters and briefings from both sides of the picture, I could not help but be convinced that this cormorant hunt is both impractical and illogical. Not surprising, really, when the government’s own wildlife experts opposed the move.

It is true that some studies have shown that cormorants can harm sport fish populations, and that their acidic guano prevents trees from growing at cormorant colonies. But the evidence for how pervasive these effects actually are is less solid. Only 2% of a cormorant’s diet consists of sport fish, and they may even help these fish by reducing competition from more widely eaten, invasive fish species, such as Alewife and Round Goby. In addition, cormorants and their treeless colonies occupy an important ecological niche (they are not, in fact, invasive in Ontario, as this fact sheet implied), similar to that of beavers and the vital ecosystems that they construct.

In terms of cormorants’ aggression towards other waterbirds, the reasoning for a cull was perhaps the most shameful misconstruction of science in this decision. The Ontario Federation of Anglers and Hunters incorrectly linked the abandonment of Lake Ontario’s only Great Blue Heron colony and a 50% drop in Great Egret populations to the presence of cormorants, when in fact it actually happened after a local culling measure similar to the one proposed was put in place. Also, while cormorants are colonial, they often nest alongside other species (and therefore do not push them out), which could be accidentally and illegally shot by game hunters.

In my view, this debate isn’t about whether or not we like cormorants, or find them pretty (I do), or like the smell they give off. They may be the issues that come to mind when Double-crested Cormorant is the story of the day, but a decision on whether to kill a bird simply for population control must, inarguably, be based on science. And science, wouldn’t you know it, supports non-intensive methods of population control — the highly successful method of egg-oiling, for example — over unenforceable shooting that could prove dangerous not only to other wildlife, but to humans in public areas, dangerously close to live ammunition.

This unjustified killing of an essential component of our fauna is neither the first nor the worst instance of an emotional response to a natural imbalance — the Eurasian Tree Sparrow and the Great Auk might share a claim to that — but it is certainly extremely disturbing, especially in the modern age.