Loggerhead Shrike government response statement

Photo: Larry Kirtley

Protecting and recovering species at risk in Ontario

Species at risk recovery is a key part of protecting Ontario’s biodiversity. The Endangered Species Act, 2007 (ESA) is the Government of Ontario’s legislative commitment to protecting and recovering species at risk and their habitats.

Under the ESA, the Ministry of Natural Resources and Forestry (the Ministry) must ensure that a recovery strategy is prepared for each species that is listed as endangered or threatened. A recovery strategy provides science-based advice to government on what is required to achieve recovery of a species.

Within nine months after a recovery strategy is prepared, the ESA requires the Ministry to publish a statement summarizing the government’s intended actions and priorities in response to the recovery strategy. The response statement is the government’s policy response to the scientific advice provided in the recovery strategy. In addition to the strategy, the government response statement considered (where available) input from stakeholders, other jurisdictions, Indigenous communities and organizations, and members of the public. It reflects the best available local and scientific knowledge, including Traditional Ecological Knowledge, at this time and may be adapted if new information becomes available. In implementing the actions in the response statement, the ESA allows the Ministry to determine what is feasible, taking into account social and economic factors.

The Recovery Strategy for the Loggerhead Shrike (Lanius ludovicianus) in Ontario was completed on June 2, 2016.

Protecting and recovering Loggerhead Shrike

Loggerhead Shrike is listed as an endangered species under the ESA, which protects both the bird and its habitat. The ESA prohibits harm or harassment of the species and damage or destruction of its habitat without authorization. Such authorization would require that conditions established by the Ministry be met.

Loggerhead Shrike’s global range is restricted to North America where it occurs across Mexico, the United States, and southern Canada. Since the 1960s, the species has experienced large declines in population sizes and retractions in its breeding range. In Canada, Loggerhead Shrike is a seasonal migrant, occurring in very small and isolated populations that are declining in numbers. The wintering grounds of Canadian birds overlap with those of permanent residents in the United States. Based on genetic studies, the Committee on the Status of Endangered Wildlife in Canada re-assessed the Loggerhead Shrike in Canada in 2014 as two sub-species: the Prairie subspecies (Lanius ludovicianus excubitorides) and the Eastern subspecies (Lanius ludovicianus ssp.). Only the Eastern subspecies occurs in Ontario and is listed as Lanius ludovicianus on the Species at Risk in Ontario List. The Eastern subspecies is also found in Manitoba and Quebec, but Ontario is the only province with breeding populations larger than a few pairs.

Loggerhead Shrikes in Ontario are mainly found and breed on the Carden Plain in the Kawartha Lakes region and the Napanee Limestone Plain in eastern Ontario. Birds have also been observed and sporadically nest in Smiths Falls, Grey and Bruce counties, and Pembroke. Known for its predatory and impaling behaviours, Loggerhead Shrike preys on a variety of fauna, including insects, spiders, frogs, snakes, small mammals and birds. Loggerhead Shrike is highly territorial and exhibits site fidelity. The species inhabits large, open, frequently-grazed grasslands situated on limestone bedrock with shallow soil or other substrates with features such as trees or shrubs, foraging areas with short grasses and bare ground, elevated perches (e.g., trees, utility wires and fence posts) and thorny branches or barbed wire for impalement of prey.

Prior to the current ESA coming into effect, Environment and Climate Change Canada and Wildlife Preservation Canada began development and implementation of a captive breeding and release program, with facilities in Ontario and Quebec. Since 2001, several hundred juvenile shrikes have been released in Ontario in an effort to improve the likelihood of the species' persistence and recovery in Ontario. The program has evolved over the years to include significant monitoring efforts and refinements to processes associated with captive breeding and release of birds. The assessment of the effectiveness of these actions provides valuable information to inform future recovery efforts.

During the first Ontario Breeding Bird Atlas (1981-1985), the population of Loggerhead Shrike in the province was estimated at 50 to 100 pairs. In the second Ontario Breeding Bird Atlas (2001-2005), the population was estimated at 18 pairs. Surveys of the Ontario population conducted by Wildlife Preservation Canada in areas of limestone plains in Carden and Napanee identified 19 breeding pairs in 2013, 14 breeding pairs in 2014, 11 breeding pairs in 2015, and 18 breeding pairs in 2016. Additional unpaired birds are also observed each year. While the number of breeding pairs observed fluctuates between years, a trend of declining numbers has been observed since at least the 1960s. The number of captive-reared birds that return to Ontario to breed fluctuates. Twelve captive-reared shrikes returned to the Ontario breeding grounds in 2016, accounting for 28% of the 43 individuals confirmed in 2016.

Despite ongoing research and recovery efforts, the population of Loggerhead Shrike in Ontario is still declining and significant knowledge gaps exist. Given the unknowns related to the survival and dispersal of non-returning wild and released birds and threats to the species outside of Ontario, it is important to fill a variety of knowledge gaps to inform future recovery efforts and evaluate the effectiveness of actions. Studies have identified that overwintering survival and recruitment into the breeding population by juvenile and young adult shrikes have the greatest effect on population dynamics. High rates of juvenile mortality following fledging have been observed in some areas of the species' distribution, but causes are unknown and it is unknown whether birds breeding in Ontario are impacted. In recent years, sightings of banded birds, as well as isotope and genetics studies, have increased the knowledge available regarding wintering locations and migration routes for the species. However, knowledge gaps still exist and further detailed information is needed. Filling knowledge gaps associated with post-fledging mortality, parasitic and viral infections, winter survival, return rates, along with continued refinements to the captive breeding program, would support and inform recovery efforts.

Habitat loss, deterioration and fragmentation have occurred in Ontario as grasslands and human-made pastures have been converted to agricultural crops, housing developments and industrial purposes (e.g., renewable energy). In remaining habitat areas, vegetation succession poses a threat because without management or grazing, unsuitable habitat conditions for Loggerhead Shrike may occur. Population declines appear to be greater than would be expected based on the extent and rate of habitat loss on the breeding grounds alone, indicating that other threats are likely involved. Habitat-related threats on the wintering grounds may also be affecting Ontario shrikes.

Declines in Loggerhead Shrike populations may also be associated with historical use of organochlorine pesticides. While the use of these pesticides was phased out in the mid-1970s and subsequently banned in Canada, monitoring of prey species in areas thought to be used by wintering birds have shown evidence of exposure to substantial levels of pesticides known to be highly toxic to birds. It is unclear if wild populations of Loggerhead Shrike are affected by pesticides and there are substantial knowledge gaps about whether pesticides and environmental contaminants on the wintering grounds and migration routes are affecting Loggerhead Shrikes that return to Ontario. Pesticides used on the breeding grounds may also affect Loggerhead Shrike through prey toxicity and reduced prey availability.

Climate change and fluctuations in the North Atlantic Oscillation (NAO) index may be contributing to the decline of the species. Fluctuations of the NAO index may affect survival or fitness of Ontario’s shrike population through its effects on temperature and precipitation on their wintering grounds. Breeding rates of many birds of eastern North America tend to be lower in years when their overwinter range is colder. Other potential threats to Loggerhead Shrike include diseases, parasites and collisions with cars. Shrikes tend to forage along roadsides using fence posts and utility poles as perches, but their swooping flight patterns put them at risk of collisions with vehicles.

Given the uncertainty associated with the causes of the species' decline, the significance of its potential threats, and the exact location and quality of its wintering habitat, it is difficult to determine the feasibility of achieving specific targets for breeding populations in Ontario. Actions to support the protection and recovery of the species will focus on research related to the location of their wintering grounds and migration routes, the significance and location of threats to the species, potential enhancements to the captive-breeding and release program, monitoring population data and trends, managing habitat on the breeding grounds in Ontario and engaging with other agencies and organizations on habitat management.

Actions

Protecting and recovering species at risk is a shared responsibility. No single agency or organization has the knowledge, authority or financial resources to protect and recover all of Ontario’s species at risk. Successful recovery requires inter-governmental co-operation and the involvement of many individuals, organizations and communities. In developing the government response statement, the Ministry considered what actions are feasible for the government to lead directly and what actions are feasible for the government to support its conservation partners to undertake.

Government-supported actions

The government endorses the following actions as being necessary for the protection and recovery of the Loggerhead Shrike. Actions identified as "high" will be given priority consideration for funding under the ESA. Where reasonable, the government will also consider the priority assigned to these actions when reviewing and issuing authorizations under the ESA. Other organizations are encouraged to consider these priorities when developing projects or mitigation plans related to species at risk. The government will focus its support on these high-priority actions over the next five years.

There are significant knowledge gaps that need to be addressed to support achievement of the recovery goal for Loggerhead Shrike. A considerable amount of research is underway, but further studies are needed to determine and assess causes of Ontario’s population declines. In particular, little is known about the wintering grounds and migration routes for Ontario’s Loggerhead Shrikes. Strong connectivity has recently been shown between birds in Ontario and Virginia and West Virginia, but more detailed information is needed about the wintering locations, migration routes and characteristics of the habitat used by the species while migrating and overwintering. Climate change, and associated changes to weather patterns, vegetation, and predation, may also have negative consequences (e.g., nest loss and brood reduction following periods of cold, wet weather). Additionally, further knowledge on the effects of pesticides and environmental contaminants on Loggerhead Shrikes is needed to inform recovery efforts. It is difficult to distinguish among subspecies in the field, resulting in very little knowledge of the extent of competition on wintering grounds between migrant shrikes and resident shrikes that occupy territories year round. Competition with shrikes and other birds on their wintering grounds may be forcing Ontario shrikes into sub-optimal habitat and affecting their overwintering survival. Engaging with the relevant authorities and organizations, including those in the United States, will support a greater understanding of the underlying limiting factors and causes of population decline occurring on the wintering grounds for Ontario’s Loggerhead Shrike population.

Actions:

1. (High) Undertake coordinated research into the ecology of Loggerhead Shrikes on their wintering grounds and migration routes, including:
   • identifying the location of their wintering grounds and migration routes (including potential stopover areas);
   • assessing the quality of habitat on the wintering grounds; and,
   • evaluating threats during migration and on wintering grounds and assessing how they influence survival.
2. Identify threats affecting Loggerhead Shrike on the breeding grounds and evaluate the significance of potential threats including:
   • habitat loss, fragmentation or deterioration;
   • effects of pesticide use and environmental contaminants (e.g., reduced prey availability, insufficient diversity of vegetation, effects on nesting success);
   • effects of climate change, extreme weather events or changes in weather patterns; and,
   • mortality along roads.
3. Conduct research to determine the rates of and factors affecting post-fledging and juvenile mortality and to assess its significance as a limiting factor on the Ontario population.
4. Coordinate efforts and share information with other jurisdictions, including partners in the United States, to increase knowledge of threats faced by Ontario-breeding Loggerhead Shrikes along migration routes and on the wintering grounds.

While knowledge gaps are being filled, it is of great importance to continue efforts to manage habitat for the specific needs of Loggerhead Shrike in Ontario. Changes in land use and succession of vegetation may contribute to the fragmentation and degradation of breeding habitat. Continued collaborative efforts to maintain and enhance habitat with local landowners, industry stakeholders and community organizations will support continued breeding of Loggerhead Shrike in Ontario and recovery efforts.

Actions:

5. (High) Develop, implement and evaluate best management practices to maintain and restore habitat for Loggerhead Shrike including maintaining appropriate vegetative diversity and where appropriate, establishing or restoring connectivity between fragmented habitat patches.
6. As opportunities arise, work with local land owners and community partners to support the securement of Loggerhead Shrike habitat through existing land securement and stewardship programs.

Continuation of the annual data collection and reporting on population trends of Loggerhead Shrike in Ontario is essential to estimate the size of remaining populations, evaluate the effectiveness of recovery actions and support informed decisions on future recovery actions. Technological advancements (e.g., tracking technology) should be pursued, as appropriate, as they may facilitate more efficient and effective monitoring. Efforts to increase population numbers will also benefit from further research. By evaluating techniques used in captive breeding, husbandry practices can be modified to increase the likelihood that released birds will return to the breeding grounds, thus improving the effectiveness of the captive breeding and release program. By studying the genetic composition of both captive and wild populations, population management actions can be monitored to maintain genetic diversity.

Actions:

7. (High) Conduct annual monitoring at known locations of Loggerhead Shrike in Ontario, and where appropriate, collaborate with established citizen science initiatives, to:
   • monitor population trends and demographics, including breeding success;
   • evaluate and refine methods for monitoring population size, distribution, fecundity, and survival of adults and young (e.g., post-fledging mortality rates);
   • monitor breeding habitat usage and assess changes in breeding habitats throughout the species' Ontario range; and,
   • use monitoring data to further refine previously completed population viability models.

8. Evaluate the effectiveness of current Loggerhead Shrike population management activities and continue to implement population management actions, such as captive-breeding and release, if deemed effective and appropriate. Additionally, conduct:
   • research to inform refinement of the husbandry and release techniques used in captive-breeding and release activities; and,
   • genetic assays to determine the genetic composition of the captive population in relation to the wild population.

Implementing actions

Financial support for the implementation of actions may be available through the Conservation Land Tax Incentive Program and the Species at Risk Stewardship Program. Conservation partners are encouraged to discuss project proposals related to the actions in this response statement with the Ministry. The Ministry can also advise if any authorizations under the ESA or other legislation may be required to undertake the project.

Implementation of the actions may be subject to changing priorities across the multitude of species at risk, available resources and the capacity of partners to undertake recovery activities. Where appropriate, the implementation of actions for multiple species will be co-ordinated across government response statements.

Reviewing progress

The ESA requires the Ministry to conduct a review of progress towards protecting and recovering a species not later than five years from the publication of this response statement. The review will help identify if adjustments are needed to achieve the protection and recovery of the Loggerhead Shrike.

Acknowledgement

We would like to thank all those who participated in the development of the Recovery Strategy for the Loggerhead Shrike (Lanius ludovicianus) in Ontario for their dedication to protecting and recovering species at risk.

For additional information

The government response statement for Loggerhead Shrike is available in PDF format upon request. Please email PDF requests to recovery.planning@ontario.ca.