Tommy Thompson Park / Leslie Spit - Toronto
The waterbird colony at Tommy Thompson Park, also known as the Leslie Spit, is dominated by nesting double-crested cormorants, ring-billed gulls and black-crowned night herons, and is currently the largest waterbird colony on the Great Lakes. The Toronto Region and Conservation Authority (TRCA) is considering using population control techniques such as egg oiling, harassment and nest removal to limit the cormorant colony at the Leslie Spit.
The TRCA are not considering shooting the birds. However, other techniques being considered can cause such extreme stress to the wild birds that it jeopardizes their overall vitality.
Please send Mayor David Miller an email supporting the natural evolution of the Leslie Spit which includes a vibrant colonial waterbird colony. Below is a sample letter to the Mayor. Please copy Councillor Paula Fletcher whose riding includes the Leslie Spit.
Please remember to include your full name and address.
For more information, please link to:www.trca.on.ca/cormorants
Techniques For Controlling Bird Populations
Harassment: Double-crested Cormorants are very sensitive birds that prefer to nest in quiet and remote islands or ‘spits’ near open water. Sometimes simple but continual harassment or disturbance such as yelling and clapping or the presence of humans is enough to permanently scare off the birds. While this may appear to be a harmless control method, it can cause such extreme stress in the wild birds that they abandon ideal nesting sites, not just for that particular nesting season, but permanently. It forces birds into less optimal habitat, and may contribute to nest failure. It may also cause loss of body mass due to stress, and compromise the bird’s overall vitality.
Egg Oiling: Egg oiling is a lethal method of population control because it aims to reduce the overall bird population. The objectives are equivalent to that of shooting but the results are achieved over a longer time period. The application of mineral oil on eggs suffocates the embryo inside, and fools the adult bird into believing their eggs are still alive. This keeps the adult sitting on its clutch and discourages re-nesting. (Cormorants will attempt to produce a second clutch if their first clutch fails. Nesting behaviour continues until summer days begin to wane - a natural marker for nesting birds that signals the end of the nesting season). Egg oiling controls bird populations by suppressing the production of hatchlings compounded by natural mortality of adults.
Double-crested Cormorants are dedicated parents and will not leave their nests during incubation. The effects of egg oiling on nesting adults can result in incubation behaviour being extended up to two extra weeks. Average incubation period is 3.5 weeks. While sitting on their nests, adults do not feed, do not drink, and are susceptible to exposure. It interferes with natural reproductive instincts, and causes disturbances similar to that of harassment.
Nest Removal: This technique involves knocking nests out of trees with long poles or destroying ground nests. To avoid re-nesting attempts by cormorants, nest removal should occur late into the incubation period destroying both nests and eggs or chicks.
David Miller, Mayor
Toronto City Hall
2nd Fl., 100 Queen St. West
Toronto, Ontario M5H 2N2
Dear Mayor Miller,
Tommy Thompson Park, also known as the Leslie Spit, has evolved into one of the greatest urban wilderness areas in North America, and boasts the largest colonial waterbird colony in the Great Lakes basin. This colony is home to the largest concentration of both nesting Double-crested Cormorants and Black-crowned Night Herons.
This dynamic colony of colonial waterbirds exists in spite of the dry waste landfill still in operation at the bottom of the ‘spit’. Many visitors to Tommy Thompson Park consider this colony a great gift, and proof of Nature’s perseverance to reclaim and repair areas of neglect. The people of Toronto are proud of the Leslie Spit.
Yet the Toronto Region and Conservation Authority (TRCA) have announced their intention to control the expansion of the waterbird colony by limiting the number of nesting Double-crested Cormorants.
Double-crested Cormorant colonies are typical of other colonial waterbird colonies found throughout the world. The large dense colonies during nesting periods serve as a natural barrier against predators that feast on cormorant eggs and chicks. These predators include other colonial birds such as Black-crowned Night Herons. Populations are self-regulating once colonies become too dense.
The Toronto Region and Conservation Authority works closely with other jurisdictions that actively promote the shooting of cormorants throughout the bird’s migration route. Partnerships between the Ontario Ministry of Natural Resources and the U.S. Fish and Wildlife Service are investigating more efficient methods to kill cormorants on their ‘flyway’, leaving no place safe for these birds anywhere.
Tommy Thompson Park has become a safe refuge for these birds.
The Toronto Region and Conservation Authority publicly states its mandate for the park is to respect the influences of natural forces in shaping the area’s biodiversity, yet the TRCA is currently considering lethal control of cormorants through egg oiling.
It would be difficult to defend the integrity of such a mandate if the action is to selectively prohibit the natural evolution of a native species deemed unwanted by city officials.
Double-crested Cormorants are beautiful birds that move energy throughout the terrestrial and aquatic ecological system of the Great Lakes. Their large dense colonies are both inspiring and humbling to witness. We are asking that your office protect the waterbird colony at the Leslie Spit, and allow it to evolve naturally without human intervention.