Midwest Region Endangered Species Conserving the nature of America

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Kirtland's warbler's first step off a branch as it takes flight.

Photo courtesy of Ashley Hannah

 

Kirtland's Warbler


Questions and Answers about the
Removal of the Kirtland’s Warbler from the List of Endangered Species

 

1. What action is the Service taking with the Kirtland’s warbler?


The Kirtland’s warbler has recovered and no longer warrants protection under the Endangered Species Act (ESA). The Service has removed ESA protection for the species in a final rule published in the Federal Register.

 

2. Why is the Service removing the Kirtland’s warbler from the federal list of threatened and endangered species?


Thanks to the efforts of many partners, threats to the Kirtland’s warbler have been significantly reduced, and measures are in place to ensure its long-term survival. The current Kirtland’s warbler population is estimated to be more than 2,300 pairs – more than double the recovery goal. The population continues to grow and has exceeded recovery goals for the past 17 years.

Although population numbers are good and seem to be growing, the Kirtland’s warbler relies on continued conservation management to maintain its recovery. This warbler needs large stands of young jack pine for nesting and brood-rearing, and it is also susceptible to cowbird parasitism. Therefore, recovery depends on continued land management that creates young jack pine stands and cowbird control.

The Kirtland’s Warbler Breeding Range Conservation Plan was developed in 2015 and is now the guiding management strategy for the species. Additionally, funding and other commitments to habitat management and cowbird control are in place to ensure continued conservation actions in the absence of ESA protections.

 

3. What is the Kirtland’s warbler?


The Kirtland’s warbler is a small songbird that nests in young jack pine forests in northern Michigan, Wisconsin and Ontario, Canada. It has one of the most geographically restricted breeding distributions of any bird in the continental United States. The exact habitat that pairs use for nesting is very specific and historically resulted from wildfire. The nesting range was probably always limited in extent but was likely common within that range before European settlement. Like the breeding range, the known wintering range is also restricted, primarily to The Bahamas.

 

4. Why was the Kirtland’s warbler listed as endangered?


Beginning in the 1940s, biologists, naturalists and birdwatchers were concerned about Kirtland’s warbler numbers based on the results of nest observations over time. To track population numbers, researchers organized the first range-wide census in 1951, a census that was repeated every 10 years until 1971, when annual surveys began. Surveys were and are conducted in the breeding season, when males can be heard singing to demarcate their territories. The number is roughly equivalent to the number of breeding pairs. In 1951 and 1961, the total population was about 1,000. The 1971 census documented a 60-percent population decline when only 203 singing males were counted, which meant there were approximately 400 warblers left in the wild. Birders and biologists were alarmed and deeply concerned that the species could not maintain itself.

 

The concern of the birding and scientific community, supported by nesting and census data, led the Service to include the Kirtland’s warbler on the list of endangered species in 1967 under the Endangered Species Preservation Act of 1966. When the ESA was passed into law in 1973, the Kirtland’s warbler was on the initial list.

 

5. What caused the Kirtland’s warbler population decline?


The Kirtland’s warbler population declined mostly for two reasons: loss of nesting habitat and brown-headed cowbird brood parasitism, which significantly reduced nesting success.

Kirtland’s warblers require large stands of young, dense jack pine forest at least 80 acres in size but preferably 300 to 400 acres or larger. Historically, large wildfires were frequent enough to provide an abundance of young stands of jack pine across the warbler’s historical breeding range (Wisconsin, Michigan and Ontario, Canada). Large-scale timber harvest and fire suppression in the early 1900s substantially reduced the size and amount of young jack pine stands available for Kirtland’s warblers to nest.

 

Habitat loss was not the only change harming warblers. At about the same time, brown-headed cowbirds expanded their range from the prairies of the Great Plains to the entire lower 48 states. Brown-headed cowbirds are “brood parasites” and will lay their eggs in the nests of other birds where the new hosts may incubate them as their own. Cowbird eggs hatch faster than other species’ eggs, giving cowbird nestlings a head start in getting food from the parents. Young cowbirds also develop at a faster pace than their nest mates and sometimes expel or smother other fledglings in the nest. The result for Kirtland’s warblers was a reduction in the numbers of young produced such that pairs were not replacing themselves.

 

6. How was the Kirtland’s warbler successfully saved from extinction?


Habitat management for the warbler began in 1957 when Michigan started managing state forest land for the species. The U.S. Forest Service followed suit and developed a management plan for the species that was approved in 1962. It was clear that providing more breeding habitat in the appropriate amounts and configurations would be necessary to increase the Kirtland's warbler population.

 

After the 1971 census documented a 60-percent decline in nesting warblers, the Michigan Department of Natural Resources (DNR) and U.S. Forest Service formed a Kirtland's Warbler Advisory Committee that included the U.S. Fish and Wildlife Service and Michigan Audubon Society. One outcome of the committee was the start of a program in 1972 to reduce cowbird parasitism in the principal nesting areas. The major agency in this effort was the Service with contributions from the Michigan DNR, Michigan Audubon Society and U.S. Forest Service. Systematic cowbird trapping in 1972 was an outstanding success and was expanded to virtually all nesting areas.

 

After the Kirtland’s warbler was listed as endangered, a recovery team was formed that included state and federal agencies and multiple partners. The team prepared the first Kirtland's Warbler Recovery Plan, which outlined steps to increase the species' population. The U.S. Forest Service and Michigan DNR developed an intensive habitat management plan to implement the nesting habitat management phase of the recovery plan. During the mid-1970s, some 134,000 acres of jack pine were designated for management as Kirtland's warbler nesting habitat within Michigan state forests and national forests. The Kirtland’s Warbler Wildlife Management Area, managed by the Service, was established in 1980 adjacent to Michigan state forest land designated for Kirtland’s warbler management. Additional state forest and national forest lands were added through the 2000s to bring the total public land specifically managed for the Kirtland's warbler to more than 210,000 acres.

 

Along with habitat management, the cowbird control program continued throughout the known nesting areas.

In response to these actions, the population increased, and the warbler’s range expanded outside the northern Lower Peninsula to areas in Michigan’s Upper Peninsula, Wisconsin and Ontario. The Kirtland’s warbler population is now about 2,000 pairs, double the recovery goal identified in the recovery plan.

 

7. How did the Service determine that the Kirtland’s warbler is recovered?


The Kirtland’s warbler recovery plan includes a recovery criterion that identifies when the warbler should be considered for removal from the List of Endangered and Threatened Species. The recovery criterion states that the Kirtland’s warbler may be considered recovered when a self-sustaining population has been re-established throughout its known range at a minimum level of 1,000 pairs. This numerical criterion has been reached and exceeded for the last 17 years.

 

In addition to reaching the numerical criterion in the recovery plan, continued recovery of the Kirtland’s warbler requires that management of pervasive and recurrent threats is assured into the foreseeable future. To address future management needs, the Service, Michigan DNR and U.S. Forest Service developed the Kirtland’s Warbler Breeding Range Conservation Plan in 2015. The conservation plan guides management efforts and outlines the strategy for future cooperative Kirtland’s warbler conservation. In April 2016, these three partners renewed a Memorandum of Understanding committing the agencies to continue collaborative Kirtland’s warbler conservation regardless of the species’ legal protection. In addition, Kirtland’s warbler conservation actions are included in the U.S. Forest Service’s land and resource management plans, which guide management priorities for the Huron-Manistee, Hiawatha and Ottawa National Forests. Additionally, the Service and Michigan DNR developed a Memorandum of Agreement for managing funds to help address long-term conservation needs, specifically brown-headed cowbird control.

 

Commitments by these management agencies through the Memorandum of Agreement and Memorandum of Understanding assure that habitat management and brown-headed cowbird control will continue at sufficient levels to ensure continued stable population numbers. These conservation assurances provide the final components needed to remove ESA protections. Given these commitments and the successful track record of proactive conservation actions carried out by cooperating agencies throughout a 50-year period, conservation efforts will likely continue to support a healthy, viable population of the species into the foreseeable future.

 

8. What is the role of timber management in Kirtland’s warbler recovery and long-term conservation?


Historically, wildfires were the most important factor in the establishment of natural jack pine forests and Kirtland’s warbler breeding habitat. However, modern wildfire suppression greatly altered the natural disturbance regime that once generated Kirtland’s warbler breeding habitat. In the absence of wildfire, land managers had to take an active role in mimicking natural processes that regularly occurred within the jack pine ecosystem. This is primarily done through large-scale timber harvesting and human-assisted reforestation.

 

Commercially selling jack pine timber on sites where reforestation will occur is critical to the habitat management program. Timber receipts offset the cost of replanting jack pine at the appropriate locations, scales, arrangements and densities needed to support a viable population of nesting Kirtland’s warblers that would not otherwise be feasible through conservation dollars.

 

9. How did Hurricane Dorian affect Kirtland’s warblers and what will the impact of increased hurricanes have on the species?


In the final delisting rule, the Service considered the impact of hurricanes on Kirtland’s warblers and their wintering grounds, in addition to the impacts of increased frequency and severity of hurricanes. 

Hurricane Dorian did not cause major damage to the central Bahamian islands, including Eluthera and Cat Island, where the largest known populations of Kirtland’s warblers overwinter. Migratory stopover habitat and some overwintering habitat may occur on Abaco and Grand Bahama Islands, and it is unclear how the habitat on those islands was impacted and if suitable habitat for the species will be present in the short-term. 

 

Hurricanes are not a unique occurrence throughout the Kirtland’s warbler’s wintering range. The Service has not detected any population level impacts to the species during previous hurricanes and believes the species has enough resilience to respond to these stochastic events. In addition, the ability to recognize large storms and temporarily move out of storm paths has been observed in other neo-tropical migrants. Kirtland’s warblers may have a similar ability to respond to weather events.

 

To detect potential threats that may arise due to increased tropical storms, the Post-Delisting Monitoring Plan directs the Kirtland’s Warbler Conservation Team to continue identifying important stop-over and wintering habitats, and monitor the species throughout its life cycle.

 

10. What is the current range of the Kirtland’s warbler?


The Kirtland’s warbler’s breeding range has expanded outside of Michigan’s northern Lower Peninsula to areas in Michigan’s Upper Peninsula, Wisconsin and Ontario, Canada.

 

Kirtland’s warblers are not evenly distributed across their breeding range. The core of their breeding range is concentrated in five counties in northern Lower Michigan (Ogemaw, Crawford, Oscoda, Alcona and Iosco), where nearly 85 percent of the singing males were recorded between 2000 and 2015.

 

In Wisconsin, Kirtland’s warbler nesting was documented for the first time in 2007. Since then, the population has grown and geographically expanded throughout the last decade. There were 49 individuals and 14 nests observed in 2018. Nesting has been documented in Adams, Marinette and Bayfield counties.

Kirtland’s warblers overwinter mostly within The Bahamas. The Bahamas is an archipelago of about 700 low-lying islands that stretches more than 650 miles from near the eastern coast of Florida to the southeastern tip of Cuba.

 

11. Will the Kirtland’s warbler population status still be monitored when it is delisted?


  Yes, the ESA requires the Service, in cooperation with states, to monitor a species for a minimum of five years after delisting, to ensure its population remains stable. The Service prepared a draft post-delisting monitoring plan that was made available for public and peer review and comment. The final plan is now available and calls for continuing the established method of population monitoring of the warbler for 12 years after delisting.

 

12. Where can I go to see a Kirtland’s warbler?


Guided Kirtland's warbler tours are available from the U.S. Forest Service and Michigan Audubon Society in Michigan. Information about tours is available at www.fws.gov/midwest/eastlansing/te/kiwa/tour.html

 

13. How can I learn more about Kirtland’s warblers and their successful recovery?


The final rule to delist the Kirtland’s warbler and supporting documents are available on http://www.regulations.gov. In the search box, enter FWS–R3–ES–2018–0005, which is the docket number for this rulemaking.

 

Additional information is online at www.fws.gov/midwest/endangered/birds/Kirtland or you may contact the U.S. Fish and Wildlife Service’s Michigan Field Office at:

 

Scott Hicks, Field Supervisor
Michigan Ecological Services Field Office
2651 Coolidge Road, Suite 101
East Lansing, MI 48823
Telephone 517–351–2555; Facsimile 517–351–1443.

If you use a telecommunications device for the deaf (TDD), please call the Federal Relay Service at 800–877–8339.

 

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