FES Profile – Gail Fraser Another York Blog

December 4, 2018

Proposed cormorant hunt Dec 2018

Filed under: — gsfraser @ 10:25 am

Comments submitted on Proposed double-crested cormorant hunt in Ontario,

EBR Registry Number: 013-4124


Gail Fraser, Associate Professor, Faculty of Environmental Studies, York University

Background. I study and teach the biology and management of colonial nesting waterbirds. Both my MSc and PhD were on colonial nesting waterbirds.  Since 2006 I have undertaken research on double-crested cormorants (hereinafter cormorants) and participated in The Toronto and Region Conservation Authority’s Cormorant Working Group.  I have an ongoing long-term monitoring project (10 yrs) following breeding chronology and productivity cormorants and black-crowned night-herons.  My students and I have also undertaken other cormorant-related research projects which fall outside of the monitoring goals. This research has thus far resulted in six peer-reviewed publications specific to cormorants and cormorant management (McDonald et al. 2018, Gupta et al. 2017, McRae et al. 2017, Andrews et al. 2012, Taylor et al. 2012, Taylor and Fraser 2011).


Introduction. In this document I respond to the proposal for a cormorant hunt in Ontario.  I structure my comments following the Policy Proposal Notice: Description of the Policy, the proposed hunting regulations, the Purpose of the Policy and Regulatory Impact Statement. Items from the proposal will be italics, my comments will follow in normal text.

Description of Policy.

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.

I am opposed to this proposal and provide rationale for my position below.

This proposal originates from the OMNRF and as such the justifications provided for a cormorant hunt should be science-based. The generic statements on double-crested cormorants without data to back such statements are a problem.  The OMNRF should have a full and detailed rationale to provide justification for this proposal, as well as population modelling exercises, population level targets to support the extreme daily bag numbers being proposed, exactly how the cormorant population will be monitored to determine effects of a hunt and an evaluation of the negative impacts on non-target species.

  1. Detrimental to fish populations. The science behind determining whether a cormorant population has a negative effect on a particular fish population is complex (Wires et al. 2003).  There are factors that could negatively impact the abundance of a particular fish population: human predation, predatory fish (multiple species), predation by other waterbirds (e.g., red-breasted merganser; Bur et al. 2008), competition from other prey which would include multiple species, abiotic considerations (e.g., water temperature) etc.   Thus, rigorous scientific studies are required for each fish population consumed by cormorants (Wires et al. 2003; see also Dorr et al. 2014 for a summary of cormorant fish predation).

As one of the presumed intentions of this proposal is to increase fish abundance by reducing cormorant predation, additional factors which influence fish populations should be considered (see Wires et al. 2003).  For example, predicted changes in the distribution and abundance of walleye due to climate change (see Van Zuiden et al. 2016); and how changes in lake ice will modify aquatic food webs (Ontario Biodiversity Council 2015) should be considered.


  1. Island habitats. Cormorants nest in high densities (Dorr et al. 2014). Where they nest in trees they will cause the mortality of trees in 10-15 years (e.g., Lemmon et al. 1994; Herbert et al. 2014) which is a natural ecological process. Cormorants do not occupy all available island habitat; they have only occupied 3% of the U.S. Great Lakes islands over a 30-year period (Wires and Cuthbert 2010).

If particular islands or forest patches that host at-risk species are being significantly modified by cormorants, local, small scale management such as deterrence and culling (e.g., Middle Island, Point Peele National Park) may be appropriate[1]. Non-lethal management, deterrence and knocking down nests, should be used first to disperse them (McDonald et al. 2018).  For roosting cormorants, a tethered raptor has successfully displaced birds (Quinn et al. 2012).

Aesthetics are presumably an additional factor for this section.  People dislike the change of a forested island to a non-forested island.   Yet, ecological processes involve change.  Cormorants are a native species to Ontario and this is what they do. On a far larger scale, humans are significantly modifying the landscape in Ontario. For example, in Ontario forest cover the mixedwood plains ecoregion is declining (Ontario Biodiversity Council 2015); and agriculture is a primary a driver of species endangerment in this ecoregion (Kerr and Cihlar 2004).


  1. Other species. In general, competition within and among species is a part of evolution and proposing a provincial wide cull because one out-competes another is a disproportionate response and not necessary.

Cormorants nest with other species both in trees and on the ground. Tree-nesting cormorants can nest among great blue herons, black-crowned night-herons, and great egrets (see Rush et al. 2015 and references therein).  Caspian terns and ring-billed and herring gulls can co-occur with ground-nesting cormorants.  This means there are a considerable number of species which could be disturbed from humans on or near colonies; and hunting activities will be detrimental to all birds nesting nearby (Carney and Sydeman 1999).  Disturbance to non-target birds would presumably violate the Migratory Bird Convention Act.

I will include comments on the positive impact cormorants have for bald eagles. Bald eagles were de-listed from the Endangered Species listing in the U.S. and their population is increasing in Ontario, though they are still listed a species of special concern in Canada (Armstrong 2014; Environment and Climate Change Canada 2017).  Bald eagles on the Atlantic coast are negatively impacting seabird colonies by preying on adults and chicks (Hipfner et al. 2012) and farmers’ chickens (Williams 2017).  In Minnesota cormorant remains were found in 40% of bald eagle nests (Windels et al. 2016). Ecologists predict a top-down effect of bald eagles on waterbird populations (Hipfner et al. 2012); bald eagles can take adult cormorants as well as juveniles and disrupt nesting colonies which can result in a site abandonment (Cairns et al. 1998; Armstrong 2014; Windels et al. 2016,). Based on other locations, it is likely that cormorants will provide a significant source of prey for bald eagles in Ontario in the near future and may assist in achieving the population recovery goal for the eagles identified by the OMNRF (Armstrong 2014).   Bald eagle predation should be incorporated into a model on what may suppress the cormorant population in Ontario.  In addition, the potential economic impact to free-range chicken farmers in reducing an abundant prey (cormorants) for bald eagles should also be under consideration.

To respond to these concerns, the Ministry is proposing to create a hunting season for double-crested cormorants in Ontario. This new population management tool would allow persons who hold a small game licence to hunt these birds.

List the double-crested cormorant as a “Game Bird”. Hunters would be required to have an outdoors card and small game licence to hunt double-crested cormorants, similar to other species of game birds.

Create an open hunting season for double-crested cormorant from March 15 to December 31 each year across the province. Create an exemption allowing small game licences to be valid for double-crested cormorant hunting in central and northern Ontario from June 16 to August 31 each year….. Monitoring of cormorants will allow the Ministry to assess the impacts of the hunting season and to adjust cormorant hunting regulations if necessary to address any concerns about population sustainability.


Unlike ducks and mergansers, cormorants have altricial young where both members of a pair are required for nest success.  The killing of either a male or a female during the breeding season will result in their chicks starving to death even if the other parent is present.  How will the sustainability of this cull be assessed in this regard? Monitoring of the cormorant population will be done presumably via nest counts, but this approach does not assess reproductive success. Where strong rationale and evidence is provided, a controlled, local cull by OMNRF would avoid this situation. At Point Peele National Park, adult cormorants are shot at the nest site early in the nesting season when no chicks are present, thus permitting a reduction in nest density but avoiding unnecessary suffering and mortality of young (e.g., Dobbie and Kehoe 2012).

Allow hunting from a stationary motorboat.

There is no mention of restricting hunting on or near colonies. Hunting on or near colonies would almost certainly disturb ground-nesting colonies, as well as disturb non-target, co-nesting species.  Cormorants will disperse to other locations; including new tree sites where available. A study using marked cormorants showed that the management actions of complete nesting failure resulted in the dispersal of adults to sites without management (Duerr et al. 2007).  The dispersing adults established 10 new colonies, and in some cases, moved up to 100 km away (Duerr et al. 2007)[2].  Disturbance to nesting sites may also have the indirect effect of increased predation on nests, thus lowering productivity even further and causing more dispersal (Carney and Sydeman 1999; Duerr et al. 2007).

There is, presumably, also a significant risk to recreational boaters given that the proposed hunting season is throughout the summer months.  When queried, the Toronto Marine Police did not know where the municipal boundary was on Lake Ontario with respect to hunting. They confirmed that at a minimum fire arm discharge would not be permitted within the harbor. Municipal boundary lines need delineation for all coastal cities and towns to ensure public safety.

The Fish and Wildlife Conservation Act currently prohibits anyone who kills game wildlife (including game birds), or who possesses game wildlife killed by hunting, from allowing that meat to spoil. Via this posting, the Ministry is also consulting on a proposal to amend the Fish and Wildlife Conservation Act to add provisions so hunters could allow cormorant to spoil. This proposal would add provisions to the Act, so that persons who lawfully hunt (or possess) cormorants could be exempt from this requirement and would be subject to conditions that require the person to retrieve and dispose of the carcass. Should this proposal proceed, it may be accompanied by regulations to implement the exemption and requirements.


A controlled, focused management action by the OMNRF is preferred over a public hunt because appropriate steps would be taken to consult the public: it would be a targeted local action; data (i.e., date, location, the number of birds shot) would be collected; a target of the number of birds to be killed would be articulated; disposal would properly occur; and other data could be gathered from the killed birds (e.g., Coleman et al. 2012).

A public hunt may disperse cormorants into new areas creating more conflicts – potentially moving ground-nesting birds to new tree or ground habitat and reduce prey for bald eagles.

A blanket open season on double-crested cormorants is not warranted and its impacts would be difficult to monitor.

The change to the Fish and Wildlife Act to permit game wastage is unprecedented, a serious change to the Act and completely unethical.


To accompany the proposed hunting seasons, the Ministry will implement a cormorant monitoring program to assess population status and trends. Monitoring of cormorants will allow the Ministry to assess the impacts of the hunting season and to adjust cormorant hunting regulations if necessary to address any concerns about population sustainability.

Cormorants are a species native to Ontario (Dorr et al. 2014, McIlwraith 1894). A significant amount of financial resources was invested in creating a healthier environment which allowed the recovery of this species; their abundance is a conservation success story (Weseloh and Collier 1995).  Should this proposal be approved, specific targets should be articulated for the cormorant population in Ontario. To avoid the species becoming endangered again, these targets should be set prior to a hunt and their populations carefully monitored.  Annual monitoring data should be released to the public on a timely basis for comment.

This proposed hunt places other aquatic waterbirds species at risk, particularly ones that nest with cormorants (herons, egrets and gulls and terns).  Disturbance from hunting on non-target birds should not be underestimated; for example, it can displace birds from foraging areas and disrupt breeding (Masden and Fox 1995; Cairns et al. 1998).  Should this proposal proceed, how will the impact on other waterbird species be monitored?

Since the proposal is for all of Ontario, enforcement and monitoring will be minimal and that alone should be the basis for a rejection of this proposal.


Literature Cited

Andrews, D., G.S. Fraser and D.V. Weseloh. 2012.  Double-crested cormorant foraging ecology at a large colony in southern Ontario: Analyses of chick diet, feeding rates and foraging directions. Waterbirds 35(sp1): 82-90.

Armstrong, E.R. 2014. Management Plan for the Bald Eagle (Haliaeetus leucocephalus) in Ontario. Ontario Management Plan Series. Prepared for the Ontario Ministry of Natural Resources and Forestry, Peterborough, Ontario. vii + 53 pp.

Brown, J., T.E. Brown and M. Lomolino 1998. Biogeography, 2nd edition. Sinauer Associates.

Bur, M.T., M.A. Stapanian, G. Bernhardt and M.W. Turner 2008. Fall diets of red-breasted merganser (Mergus serrator) and walleye (Sander vitreus) in Sandusky Bay and adjacent waters of western Lake Erie. American Midland Naturalist 159(2):147-161.

Cairns, D.K., R.L. Dribblee and P.Y. Daoust 1998. Displacement of a large double-crested cormorant, Phalacrocorax auritus, following human disturbance. Canadian Field Naturalist 112: 520-522.

Carney, K. and W.J. Sydeman 1999. A review of human disturbance effects on nesting colonial waterbirds. Waterbirds 22(1):68-79.

Coleman, J.T.H., C.M. Adams, M. Kandel and M.E. Richmond 2012. Eating the invaders: the prevalence of round goby (Apollonia melanostomus) in the diet of double-crested cormorants on the Niagara River. Waterbirds 35(Sp1):103-113.

Dobbie, T. and J. Kehoe 2012. Point Peele National Park of Canada Middle Island Conservation Plan Summary Report 2008-2012. Parks Canada.

Dorr, B.S., J.J. Hatch and D.V. Weseloh 2014. Double-crested cormorant (Phalacrocorax auritus), v. 2. In The Birds of North America (P.G. Rodewald, Ed.). Cornell Lab of Ornithology, Ithaca, New York.

Environment and Climate Change Canada, 2017. North American Breeding Bird Survey – Canadian Trends Website, Data-version 2015. Environment and Climate Change Canada, Gatineau, Quebec, K1A 0H3.

Gupta, A., K. Rudmik and G.S. Fraser. 2017. The effect of double-crested cormorants (Phalacrocorax auritus) on habitat and invasive European fire ants (Myrmica rubra). Canadian Field Naturalist 131: 347-349.

Herbert, C.E., J. Pasher, D.V.C. Weseloh, T. Dobbie, S. Dobbyn, D. Moore, V. Minelga and J. Duffe 2014.  Nesting cormorants and temporal changes in island habitat. Journal of Wildlife Management 78(2):307-313.

Hipfner, M.J., L.K. Blight, R. W. Lowe, S.I. Wilhelm, G.J. Robertson, R.T. Barrett, T. Anker-Nilssen and T.P. Good 2012. Unintended consequences: how the recovery of sea eagle Haliaeetus spp populations in the northern hemisphere is affecting seabirds. Marine Ornithology 40(2012) s. 39-52.

Kerr, J.T. and J. Cihlar 2004. Patterns and causes of species endangerment in Canada. Ecological Applications 14(3):743-753.

Lemmon, C.R., G. Bugbee and G.R. Stephens1994. Tree damage by nesting double-crested cormorants in Connecticut. Connecticut Warbler 14:27-30.

Masden, J. and A.D. Fox 1995. Impacts of hunting disturbance on waterbirds – a review. Wildlife Biology 1(1):193-207.

McDonald, K., R. Toninger, A. Chreston, I. Feldmann and G.S. Fraser. 2018.  Living with double-crested cormorants (Phalacrocorax auritus): A spatial approach for non-lethal management in Toronto, Canada. Waterbirds 41(2): 208-220.

McIlwraith, T. 1894. The Birds of Ontario. Briggs, Toronto.

McRae, M., M. Azadbakhsh and G.S. Fraser. 2017. The advertising display of double-crested cormorants varies with microhabitat and time of the season in a tree-nesting colony. Acta Ethologica 20(3): 319-327.  

Ontario Biodiversity Council 2015. State of Ontario’s biodiversity 2015 indicators. http://sobr.ca/_biosite/wp-content/uploads/SOBR-2015_all-indicators_May-19-2015.pdf

Quinn, J.S., M. Lozer and C.M. Somers 2012. Tethered raptor displaces roosting cormorants. Waterbirds 35 (sp1): 77-81.

Rush, S.A., C. Pekarik, D.V. Weseloh, F. Cuthbert, D. Moore and L. Wires 2015. Changes in heron and egret populations on the Laurentian Great Lakes and connecting channels 1977-2009. Avian Conservation and Ecology 10(1):7.

Taylor, B., D. Andrews and G.S. Fraser. 2011. Double-crested cormorants and urban wilderness: conflicts and management. Urban Ecosystems 14: 377-394.

Taylor, B. and G.S. Fraser. 2012. Effects of egg oiling on ground nesting double-crested cormorants at a colony in Lake Ontario: an examination of nest-attendance behaviour. Wildlife Research 39(4): 329-335.

Van Zuiden, T.M. and S. Sharma 2016. Examining the effects of climate change and species invasions on Ontario walleye populations: can walleye beat the heat? Diversity and Distributions 2016:1-11

Weseloh, D.V. and B. Collier 1995. The rise of the double-crested cormorant on the Great Lakes: Winning the war against contaminants. Environment Canada, Great Lakes Fact Sheet.

Williams, W. 2017. When the national bird is a burden. The New York Times Magazine Jan 19, 2017. https://www.nytimes.com/2017/01/19/magazine/bald-eagle-national-burden.html

Windels, S.K., H.T. Pittman, T.G. Grubb, L.H. Grim and W.W. Bowerman 2016. Bald eagle predation on double-crested cormorant and herring gull eggs.  Journal of Raptor Research 50(2):230-231.

Wires, L.R. and F.J. Cuthbert 2010. Characteristics of double-crested cormorant colonies in the U.S. Great Lakes island landscape. Journal of Great Lakes Research 36:232-241.

Wires, L.R., D.N. Carss, F.J. Cuthbert and J.J. Hatch 2003. Transcontinental connections in relation to cormorant – fisheries conflicts: perceptions and realities of a “bête noire” (black beast) on both sides of the Atlantic. Vogelwelt 124:389-400.

[1] Though in the case of Middle Island, I would argue a cull is not warranted as the Carolinian species are at-risk because they are at the northern edge of their range (see Brown et al. 1998 for concepts on species range and abundance).

[2] While there was a significant banding effort for cormorants in the early 2000s in Ontario and some banded birds remain, there is no effort in re-sighting marked birds before and after the hunting would occur, to establish residency and change of residency.

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