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The Double-Crested Cormorant: A Villain That Deserves to Be Killed?

Updated: Feb 26, 2019


Photo by Veni-Vidi Vint

The Ontario provincial government is considering a cull on a bird that was threatened and nearly endangered in the 1960s, the double-crested cormorant. The proposal is to open up a hunt on the water birds with a bag limit of 50 birds per person per day. As well, they would amend the Fish and Wildlife Conservation Act to add provisions so hunters could allow cormorant meat to spoil as currently it is illegal to allow the meat of game to be wasted. Te Government of Ontario states, “There continues to be concerns expressed by some groups (commercial fishing industry, property owners) and individuals that cormorants have been detrimental to fish populations, island forest habitats, other species and aesthetics.”¹ The claim is that the cormorants are depleting fish populations through predation and that their toxic guano (seabird excrement) is killing trees, damaging the ecosystem, and ruining aesthetics. First off, killing a species of bird for aesthetic purposes is ridiculous — I'm not even going to touch that one. But how about the other reasons? What effect do double-crested cormorants have on aquatic and terrestrial ecosystems? What are the facts?


As for aquatic ecosystems, studies have shown declines in game fish but comprehensive studies have been limited likely “owing to cost, complexity, and duration necessary to draw reliable conclusions — and even then results may be ambiguous”.² Cormorants are opportunistic feeders, relying on whatever fish is easiest for them to prey on and is most abundant. This means that as a species’ numbers are reduced, cormorants will switch to feeding on another species that is more plentiful. When left alone, this predator-prey relationship will cause populations of cormorants and species of fish to fluctuate just as with Canada lynx and snowshoe hares. You don’t cull the lynx when the snowshoe hare population drops, it naturally corrects itself. Double-crested cormorants are not some introduced species that is decimating the aquatic ecosystem but are, in fact, an integral part of it. In actuality, some of the species of fish that people are trying to protect are the introduced species. It seems peculiar that we should protect these introduced fish over a native bird entirely because they have recreational and commercial benefits.


When it comes to the impact on terrestrial ecosystems, double-crested cormorants nest in colonies on bare ground or in trees. When nesting in trees the habit of stripping leaves for nest building and the composition of their guano — which lowers the PH of the soil — combine to eventually kill the trees. When the trees die, the cormorants often continue to nest on the downed trees and on the ground, preventing the regrowth of the trees and creating open areas for nesting. While these open areas can negatively affect some species, they also have positive effects on species that nest in open areas such as American white pelicans and herring gulls.³ This process has gone on for thousands of years with many species adapting to live together forming symbiotic relationships. Why would we feel that it suddenly needs human management?


We know that there is no conclusive scientific evidence for a cull but on top of that let's talk about the ethics and the responsibilities that we have as stewards of these areas. Adjusting the Fish and Wildlife Conservation Act to allow for the meat of this “game bird” to be wasted is unethical. Why make an exception for this species? Does that seem right? As for the bag limit of 50 birds per day per person; that is unreal. This type of mass killing of a species is simply irresponsible. The talk of opening up this kind of hunt on cormorants can’t help but make me think of the now extinct passenger pigeon and how humans caused the downfall of that species.


Passenger pigeons are thought to have once been the most numerous land bird in all of North America, making up as much as a quarter of North America’s avifauna.⁴ This bird’s populations were decimated in the second half of the 1800s through habitat destruction, hunting, and the destruction of nesting colonies. In a mere 30 years double-crested cormorants went from abundant to extinct.⁵ The story of the passenger pigeon is a tragic one that becomes even more tragic if we do not learn from it. Open season on a species with limited restrictions combined with a campaign of hate towards the species can have disastrous consequences. Do we really want to risk making the double-crested cormorant the next passenger pigeon?


As for the double-crested cormorant, they’re a native bird that has been a part of our North American ecosystems for millennia. Should we villainize them and once again bring them to the threatened status they had in the 1960s? I think the obvious answer is no.


1. Environmental Registry of Ontario. (2018). Proposal to establish a hunting season for double-crested cormorants in Ontario.

2. Dorr, B. S., Hatch, J. J., & Weseloh, D. V. (2014). Double-crested Cormorant (Phalacrocorax auritus), v. 2.0. The Birds of North America (PG Rodewald, Ed.). Cornell Lab of Ornithology, Ithaca, New York, https://doi.org/10.2173/bna, 441.

3. Dorr, B. S., Hatch, J. J., & Weseloh, D. V. (2014). Double-crested Cormorant (Phalacrocorax auritus), v. 2.0. The Birds of North America (PG Rodewald, Ed.). Cornell Lab of Ornithology, Ithaca, New York, https://doi.org/10.2173/bna, 441.

4. Schorger, A. W. (1955). The passenger pigeon: its natural history and extinction (Vol. 424). Madison: University of Wisconsin Press.

5. Blockstein, D. E. (2002). Passenger pigeon: ectopistes migratorius. American Ornithologists' Union.