Hyperabundant species management

Point Pelee National Park

The preservation of ecological integrity is a crucial part of natural area conservation.

  • Ecological Integrity: The components and processes that are typical of a healthy ecosystem are intact and working, supporting the native species that live there.

Maintenance and restoration of ecological integrity has been legislated as the first priority for the management of National Parks in the "Canada National Parks Act" (2000). Parks Canada, being charged with this responsibility, takes actions to protect the ecological integrity of habitats in national parks, and contributes to the management and recovery of species at risk. These actions can include the management of hyperabundant wildlife populations.

A species is considered hyperabundant when its population has grown too large for the natural area to support it, and/or when it negatively affects species at risk. Native species generally become hyperabundant as a result of human-induced changes to the ecosystem that cause their populations to grow unchecked. The "Directive on the Management of Hyperabundant Wildlife in Parks Canada’s Heritage Places" (2019) states that hyperabundant wildlife populations must be actively managed in national parks when:

  • Population growth is no longer fully regulated or kept in check by natural processes, and
  • Research suggests that species at risk, ecological health, and/or ecological sustainability have been or are likely to be damaged or compromised by the hyperabundant populations.

Monitoring and research at Point Pelee National Park have identified two hyperabundant wildlife populations: white-tailed deer (on the mainland) and double-crested cormorants (on Middle Island). The size of these populations are a threat to species at risk and to the natural processes that are expected in this ecological region of Canada.

Mainland vegetation and white-tailed deer (Odocoileus virginianus)

Point Pelee National Park sits in an ecological region called the Carolinian zone. This zone has a warmer climate than other parts of Canada and is home to a diverse variety of plant and animal species. This rich biodiversity is part of what makes the park so unique. There are more rare species found in this zone than in any other region of the country. Point Pelee National Park is home to the largest natural area in Essex County, and is made up of a patchwork of beach, marsh, savannah, dry forest, and swamp forest.

The Problem

Ecosystem integrity relies on a balance within and amongst the numerous species that are native to a natural area. White-tailed deer populations in southern Ontario have been increasing due to a combination human induced changes, including:

  • Climate Change: Warmer winters with less snow cover resulting from climate change, increases food availability and winter survival rates;
  • Lack of Predators: Large predators would normally keep deer populations in check. When large numbers of settlers arrived in Southwestern Ontario including the Point Pelee Peninsula, large portions of forest areas were converted to farmland or residential areas and no longer provided habitat for large predators like bears, cougars and wolves, who need large ranges. Settlers also aggressively hunted these predators until the last were extirpated from this area in the 1800s.
  • Landscape changes: Human alterations to the landscape can create conditions where deer thrive. Deer adapted to the agricultural landscape where habitat edges along farm fields provided ideal areas for grazing and cover. When farming ceased in the park in the 1970s and these farms were abandoned. The land regenerated and young forests with lots of leafy and woody food became available for deer, which also boosted their populations.

For Point Pelee National Park, these factors have resulted in a large deer population and increased deer browsing of native vegetation, including several species at risk. When deer over browse and cause the loss of undergrowth in a forest, this takes away the places for small animals and birds to shelter and nest. The result is the disappearance of many native species that no longer have access to the habitat and food they need. Over browsing can significantly alter understory light conditions in park forests. Increased light levels can then drive changes in the understory vegetation, allowing alien invasive species to gain an advantage and suppress native woodland species, which are adapted to shade.

In addition, deer frequently behave as selective foragers, preferring native plant species to alien invasive species, further providing an advantage for alien invasive plant species. Invasive plant species can cause irreparable damage to important habitats and ecosystems, putting our native plants and animals at risk. A hyperabundant population of deer can also hinder restoration efforts in ecosystems at risk. For example, when Parks Canada staff plant native species as part of the Lake Erie Sand Spit Savannah (LESSS) restoration program, these plants can quickly be eaten up by deer

Studies on browsing and forest health first linked deer browsing to negative impacts on the park’s vegetation communities in the late 1980s, and surveys have been conducted to document the deer population in the park since 1987. Based on guidelines for general forest regeneration and development, it is estimated that the park could support 24 to 32 deer (6 to 8 deer per km2) without adversely affecting forest regeneration. The current deer population is higher than the park’s capacity. The ongoing need for deer management is identified in Point Pelee National Park’s Management Plan, State of the Park Report, and Integrated Vegetation Management Plan.

Over browsed vegetation
Over browsed vegetation
Over browsed oak sapling
Over browsed oak sapling

Management Actions

After evaluating a variety of management options, with considerable public and stakeholder consultation in preparing the “Hyperabundant Deer Management Plan for Point Pelee National Park” (2014), Parks Canada staff began active hyperabundant species management through deer herd reduction. This management action was found to be the most effective and feasible option, as it mimics natural predation, has no direct impact on other species, follows Parks Canada’s Animal Care Task Force guidelines, is cost-effective, and is supported by stakeholders and Indigenous communities. Because Point Pelee National Park’s deer herd reduction is carefully planned and managed, and takes place during a low visitation period, it also minimizes safety risks and impacts to visitors.

Each year, forest health indicators are monitored and the deer population is counted. These data are important, as they inform decisions on how to make adjustments to deer management operations. Parks Canada staff consult with Caldwell First Nation to plan each year’s deer herd reduction. The park is closed to the public during the reduction activities.

The goal of hyperabundant deer management at Point Pelee National Park is to restore and maintain the ecological health of the natural habitats in the park. Point Pelee is committed to adapting management decisions over time, based on data gathered from research and monitoring. When data show that the deer population can be supported by the vegetation in the park, without significantly compromising species at risk or the health of the natural systems, then management actions for deer will be re-evaluated.


Parks Canada’s Hyperabundant Management Directive encourages national parks to first consider working with Indigenous peoples when managing hyperabundant wildlife. Point Pelee National Park has formed a First Nations Advisory Circle with both Caldwell and Walpole Island First Nations, where Indigenous partners participate in the planning and delivery of programs and initiatives within the park. The First Nations Advisory Circle was invited to review the park’s plan for managing hyperabundant deer, and Caldwell First Nation has been instrumental in deer herd reduction operations since 2009. The reduction activities are an opportunity for Caldwell First Nation to mentor youth and strengthen traditional connections to the land. Deer taken through the herd reduction are used by Caldwell First Nation for personal, community, and ceremonial purposes.

Middle Island and double-crested cormorants (Phalacrocorax auritus)

In 2000, the Nature Conservancy of Canada transferred Middle Island, the southernmost land area in Canada, to Point Pelee National Park. It is an important part of the small Carolinian ecozone, which makes up only 1% of the Canadian landmass. The island’s landscape provides clues into what a lot of southern Ontario looked like before European settlement. Middle Island is also home to several species at risk, designated by the Canada Species at Risk Act and/or the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) These species include blue ash, common hoptree, Kentucky coffee tree, red mulberry, wild hyacinth, eastern foxsnake, Lake Erie watersnake, barn swallow, shagreen, eastern banded tigersnail, and monarch butterfly.

The Problem

Tree with many double-crested cormorant nests on Middle Island
Tree with many double-crested cormorant nests on Middle Island

In 1987, there were 3 double-crested cormorant nests found on the island. Thirteen years later, when Parks Canada acquired the island, this had increased to 5,202 nests, and vegetation monitoring was showing a drastic reduction in forest canopy cover. Though cormorants are native to North American, their population has exploded in recent years. Four main events are believed to have contributed to an increase in cormorant population numbers:

  1. Changes in fish populations in the Great Lakes: Increased availability of certain fish species, such as newly introduced invasive species (e.g. alewives and round gobies), produced new food sources for cormorants; and
  2. Increased over winter survival: This is linked to catfish farms in the southern United States, which can act as a reliable supply of food for cormorants.
  3. The banning of DDT and associated pesticides: This was a needed action to address DDT toxicity and its persistence in the environment which causes it to bioaccumulate (build up in living tissues) and biomagnify (increase in concentration in moving up the food chain). With the banning of this pesticide, concentrations in the environment decreased, improving cormorant breeding success and therefore increasing cormorant populations;
  4. Changes to federal and state conservation laws: These changes offered additional protection to cormorants;

Research and monitoring revealed that the high number of cormorant nests on the island was causing significant and potentially irreversible damage to the island’s native vegetation communities, and was threatening the species at risk that call Middle Island home.

The trees and vegetation on the island are largely impacted by the accumulation of cormorant feces, or guano. Cormorant guano is acidic, and deposits on the soil can change soil chemistry, which can jeopardize the growth of native vegetation. Guano can also coat leaves, inhibiting photosynthesis - the process of plants using light, water, and carbon dioxide to grow.

Great Blue Heron on Middle Island
Great Blue Heron on Middle Island

Published research has linked declines in forest cover with double-crested cormorant nest numbers on several islands in the Lake Erie western basin, including Middle Island (1). This loss in forest cover reduces the available habitat for other colonial waterbird species on Middle Island, such as great blue herons and black-crowned night herons, that depend on it for breeding. Research on individual colonies has shown that double-crested cormorants can displace other nesting waterbirds through habitat loss, and direct competition for nests and nesting sites.Other cormorant-driven impacts on Middle Island have included reduced diversity in understory vegetation and changes in the distribution and composition of native fauna.

Point Pelee’s Management Plan, State of the Park Report, and Integrated Vegetation Management Plan all identify hyperabundant double-crested cormorants as a threat to the habitats and species at risk on Middle Island. Without intervention, the biologically diverse vegetation and complex ecosystem on Middle Island would be lost entirely.

Management Actions

In considering how to protect the vegetation and species at risk on Middle Island, many management options were explored, including nest destruction, cormorant displacement, artificial nesting platforms, predator reintroduction, and egg oiling. After evaluating these options and how they could be applied, Parks Canada staff put in place three hyperabundant species management actions: adult double-crested cormorant reduction, scarecrow deterrents, and nest removal.

Cormorant reduction is species-specific, logistically and economically feasible, and immediately effective (which is necessary for the high number of cormorant nests on Middle Island). Based on recommendations from the Parks Canada Animal Care Committee, cormorant reduction is planned for early in the nesting season, before egg hatching, to avoid impacts on cormorant young. Scarecrows and nest removal activities are used in specific areas on Middle Island, where individual species at risk need protection. These methods are not suitable for use over the whole island, but are effective when applied to smaller areas.

Double-crested cormorants are native within the Great Lakes, so the goal of their management on Middle Island is not to eliminate them. Instead, the goal is to reduce the number of nests, in order to restore ecological health and protect species at risk. The target for the density of cormorant nests on the island is 30-60 nests per hectare, in keeping with what would allow the island’s diverse native vegetation communities to persist. As of 2017, research and monitoring has shown an increase in healthy forest canopy cover, desirable herbaceous species, and many species at risk populations. These are good indicators that current management actions are working.

Monitoring of cormorant nests, vegetation health, and species at risk populations will continue on Middle Island. Hyperabundant species management is adaptive, so that it can be changed as conditions change, as the number of cormorant nests change, or as new information becomes available.

Public access to Middle Island is prohibited between March 1st and September 1st each year. This is required in order to minimize disturbance to nesting colonial waterbirds on the island (such as great egrets, great blue herons, black-crowned night herons, and herring gulls, in addition to double-crested cormorants), and to prevent danger to visitors when cormorant reduction activities are taking place.


Parks Canada is working with numerous partners in relation to monitoring, research, and management on Middle Island. Academic institutions (e.g. the University of Windsor, the University of Waterloo and Carlton University) and other organizations (e.g. the Canadian Wildlife Service, Ontario Parks, United States Fish and Wildlife Service, Ohio Wildlife Service) have contributed to research and monitoring of various factors such as parasites, contaminants, and regional population and management trends. Since 2008, more than 8 scientific papers and 2 Master’s theses have been completed from collaborative research on the island facilitated by Parks Canada.

The Middle Island Conservation Plan, which details how cormorant nesting numbers on Middle Island are managed, was developed in consultation with First Nations, partners, stakeholders, communities, and the public.

1) See Hebert et al., 2014. Nesting Cormorants and Temporal Changes in Island Habitats. Journal of Wildlife Management 78:307-313.

Frequently asked questions on deer management

Why are there so many deer in Point Pelee National Park?

Deer populations in Southwestern Ontario have increased due to land use changes and removal of predators. Prior to settlement, the area was covered in dense forests and wetlands, which provided habitat for predators of deer, such as bears, wolves, and cougars. As settlers arrived, wetlands were drained and forested areas were cleared and converted to farmland and residential areas. This habitat became ideal for deer as they are highly adaptable, whereas their predators were not. Predators were also aggressively hunted until they disappeared from the area. With the deer’s ability to adapt to the agricultural landscape and with no predators to regulate their population, herds were able to grow unchecked, resulting in the hyperabundant populations we have today.

Now, Point Pelee National Park is home to a large amount of leafy vegetation, experiences mild winters, and, most importantly, lacks natural predators such as wolves, bears and cougars which would have normally kept the deer population in balance. This has led the population of white-tailed deer to grow to unsustainable numbers in the park.

Why is Parks Canada reducing the deer population in Point Pelee National Park?

Parks Canada is a recognized leader in conservation and is working in partnership with First Nations to ensure the long-term health of Point Pelee National Park. Parks Canada and Caldwell First Nation are taking steps to actively protect the sensitive ecosystems at the park by reducing the hyperabundant deer population.

Research and monitoring suggest that a healthy, balanced ecosystem at Point Pelee National Park would ideally support 24 to 32 deer. The current deer population is estimated to be between 61 and 73 deer, which is two times higher than the park’s capacity, and this population size negatively impacts the health of the forest and savannah, and the species that depend on them.

The deer reduction operation is part of the park’s Hyperabundant Deer Management Program, which includes ecosystem monitoring, deer population monitoring, species at risk protection, ongoing research and collaboration, and reducing the white-tailed deer population to sustainable levels based on the park’s goal to achieve ecological integrity, that is, the health and wholeness of the environment and nature.


Through overbrowsing, the deer in the park are consuming and damaging native plants faster than they can regenerate. This threatens the health of the Carolinian Forest which is home to several species at risk such as the Red Mulberry Tree, Eastern Wood-Pewee and Eastern Foxsnake. Native plants serve as habitat and food sources for other species and the overbrowsing of native vegetation results in the decline of species such as birds and insects.

Heavy browsing by deer also jeopardizes the park’s efforts to restore the Lake Erie Sand Spit Savannah, a globally rare ecosystem that supports 25% of the species at risk in the park, including the Five-lined Skink.

If the deer population remains at current levels, the park’s native vegetation will not be able to regenerate and sustain itself. This, in turn, will degrade ecosystem health and affect the other species that rely on healthy vegetation communities.


Hyperabundant deer populations mean there are large numbers of deer in small areas, which leads to increased risk of serious deer diseases that may affect both deer and people. High deer numbers increase the risk of transmission of diseases like Chronic Wasting disease, which is a serious threat to deer and has been found in the northeast United States, including along the eastern border with Ontario. Additionally, high deer density has been linked with increased prevalence of Lyme disease.

Have you seen improvement in the park since the deer reduction activities resumed?

We can confirm that less damage to the vegetation from deer browsing has been observed in the park since annual deer herd reductions resumed in 2015. However, significant improvements in vegetation regeneration, especially seedling tree growth, can take a long time. The deer population continues to be higher than what the park can sustain, therefore it is not expected that park vegetation communities will show significant improvements until the population reaches and is maintained at a level of 24 to 32 deer, which past research and monitoring suggests would promote a healthy, balanced ecosystem at Point Pelee National Park.

Parks Canada will continue to monitor and reduce the deer population in the absence of predators as part of the park’s Hyperabundant Deer Management Program, which includes ongoing monitoring programs measuring forest health and vegetation regeneration.

How many deer are currently in the park?

Counts conducted in winter 2023 estimated the deer population to be between 59 and 70 deer. Updated herd numbers will be confirmed by an aerial survey in the winter of 2023/24, if weather conditions permit.

Research and monitoring suggest that a healthy balanced ecosystem in Point Pelee National Park would ideally support 24 to 32 deer. Therefore, the current estimated park population size is at least two to three times higher than what is sustainable.

Why is Parks Canada conducting a deer herd reduction in November and then again in January?

In partnership with Caldwell First Nation, Point Pelee has reduced the hyperabundant deer population by half since 2015; however, the estimated current population (59 to 70 deer) is still two times higher than what the park can sustain. Since 2008, the white-tailed deer population has remained higher than the target density suggested by literature and research (24 to 32) and established monitoring programs have not indicated the desired regeneration of forest and savannah habitats.

To achieve these goals, Parks Canada and Caldwell First Nation Chief and Council (with the additional consultation of the Caldwell First Nation community) collaboratively decided to split the deer herd reduction to two operations:

  • Breeding season for deer, also called the rut, is from October to December making it a potentially more effective time to conduct a population reduction. During the breeding season, deer can become more active during the daylight hours, wander into open areas in broad daylight and often become less wary due to interest in breeding, which may increase deer presence at the blinds and the number of deer removed during this period of the population reduction.
  • Historically, harsh winters in the park have led to less vegetation being available for deer in the park to feed on. As such, deer have been drawn to the bait provided during reduction activities in January. However, Point Pelee National Park is experiencing increasingly mild winters and even in January, ample vegetation remains available for deer to browse, potentially reducing their interest in bait.
  • Evidence in previous years has shown that the number of deer visiting the blinds is considerably reduced by the second week of operations. By separating the population reduction into two, shorter operations, the habituation of deer to the operation should be reduced and the overall efficiency of the operation should increase.
  • The duration of the deer herd reduction and associated park closure this season is the same as in prior seasons, with a total of 16 days planned which includes both November and January operations. The January operation will occur later in the month, this will allow the park to remain open during the Christmas Break and increase the potential for snow cover during the operational period.

Ongoing monitoring programs measuring the health of ecosystems in the park will determine if new methods may be required to achieve a sustainable deer population and improve the health of the forest and savannah ecosystems at Point Pelee National Park.

Where are all the deer in the park? Why don’t visitors see them?

Point Pelee National Park is approximately 15 km2 and the majority of that area is not visible from the main park road. Many of the deer stay in and around the marsh and in the interior forest, away from public areas and trails. In winter, studies have shown that deer prefer the dense forest cover of the cedar trees and sumac stands. In summer, when leaves are on the trees, deer can be near roads or trails without being visible to visitors. However, wild deer populations naturally prefer areas away from the threat of humans and the noise from vehicles and buildings.

Deer are most active during dawn and dusk, so this would be the best time to catch a glimpse of them in the park.

What will happen to the meat and hides from the herd?

The deer will be used by the Caldwell First Nation for personal, community, and ceremonial purposes, and will not be sold for profit.

What other alternatives has Parks Canada considered prior to selecting lethal reduction?

Parks Canada is a recognized leader in conservation and takes actions to protect national parks and national marine conservation areas and contribute to the recovery of species at risk. Parks Canada’s collaborative, data-based, and adaptive approach to hyperabundant species management in national parks follows policies for humane treatment of wildlife and public and employee health and safety.

Parks Canada has examined the feasibility of management options with wildlife management specialists and conducted extensive public and stakeholder consultations to explore a wide range of approaches to reduce the impacts of hyperabundant deer. These options have included capture and relocation, fertility control, predator reintroduction, deer feeding programs, and vegetation management. Population reduction through culling was chosen as the preferred and most feasible option to remove deer from the park. This method most closely imitates the predator-prey cycle, the natural process that would have controlled the deer population regionally prior to post-colonial settlement and urbanization.

Why isn’t the public able to participate in this reduction?

The purpose of the deer population reduction is not to provide a recreational hunting opportunity. Rather, it is a resource management intervention designed to reduce a major threat to the continued health of the park. Point Pelee National Park is within the traditional territory of Caldwell First Nation and Parks Canada has a Memorandum of Understanding with Caldwell First Nation to manage the hyperabundant deer population within the boundaries of Point Pelee National Park.

Working with Indigenous partners is a priority for Parks Canada. At Point Pelee National Park, we work with local Indigenous communities on a variety of projects such as the interpretation of First Nations history within the park, and the sharing of knowledge and conservation practices including how best to protect species at risk. We are committed to working together to improve the health of Point Pelee National Park in an environment of respect, co-operation, and partnership.

What is the science behind the plan to reduce the deer population in the park?

The decision to reduce the deer population in the park is based on deer population monitoring results, vegetation monitoring results, and the 2014 Hyperabundant Deer Management Plan for Point Pelee National Park created to meet legislated National Park requirements in protecting ecological integrity and species at risk.

This plan was developed through 30 years of research, monitoring, relevant case studies, recommendations from experts, and in collaboration with Indigenous partners.

While there are many ways to reduce the population, a controlled annual cull was chosen as the most feasible option to remove deer from the park because this method most closely imitates predation, the natural process that would have controlled the deer population prior to colonial settlement and urbanization.

What are deer exclosures and why are you putting them throughout the park?

Exclosures are sturdy fenced-in areas that are designed to keep certain species out of a natural area so that we can monitor how the vegetation responds to that species’ absence.
The results of this monitoring will help determine the impact deer have on forest regeneration.

Learn more about vegetation monitoring and White-Tailed Deer in the park.

Were the new tactics tried in 2023/2024 successful? Will you be trying anything new again?

Parks Canada and Caldwell First Nation jointly planned and carried out a safe and humane operation that reduced the number of deer in the park. These are all measures of success and remain the priorities for the Deer Herd Reduction.

However, our data shows that despite this success, the deer population is still higher than what the park can support. We have some lessons learned from these new tactics (i.e. splitting the operation into two sessions in November and January), and have identified existing tactics that are contributing to success. Parks Canada and Caldwell First Nation will continue to evaluate these tactics and determine which will be carried forward in the future to achieve the target deer population.

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