Whooping crane (Grus americana) recovery strategy: chapter 2

2. Recovery

2.1 Recovery Feasibility

The goal of this recovery strategy is to protect, restore, and manage Whooping Cranes to be self-sustaining in the wild and to downlist the species from endangered to threatened under the Canadian Species at Risk Act and the U.S. Endangered Species Act, ultimately setting the stage for delisting. Specific strategies are identified and, if implemented, should achieve that goal. The Whooping Crane may never be abundant, based on the past history of this species, its low reproductive rate, and threats to habitat required for breeding, migration, and wintering. Preserving this species will require the interest and concern of an informed public. Based on overall habitat availability, a positive growth rate, and success in captive breeding, the recovery potential of the species is high.

The inherent capacity of Whooping Cranes to rebound demographically is low due to delayed sexual maturity (age 3–4 years) and a low reproductive rate (two eggs in the annual nesting attempt, with only one chick typically fledging). However, breeding experience and longevity somewhat compensate for their low reproductive rate.

The present nesting habitat at Wood Buffalo National Park may not be as productive as the historical nesting wetlands in the prairie grasslands (B. Johns pers. comm.). However, Wood Buffalo National Park provides suitable protected nesting habitats that have supported population recovery from 3 or 4 nesting pairs in 1941 to 62 nesting pairs in 2006. Sufficient migratory stopover habitat is available to support the present population and numbers likely to be attained in the near future. Winter habitats at Aransas are currently sufficient to support at least 500 individuals (T. Stehn pers. comm.).

Threat factors have been alleviated to a degree sufficient to allow an average annual growth of 4.5% for the last half century in the AWBP. The cooperative protection plans implemented by provincial, state, and federal agencies are believed to have reduced losses due to shooting and disease (Lewis 1992). Some power lines have been marked to increase visibility and help reduce Whooping Crane mortality, a technique shown to reduce Sandhill Crane collisions with power lines (Morkill 1990; Morkill and Anderson 1991; Brown and Drewien 1995). Erosion losses of critical winter habitat along the Gulf Intracoastal Waterway have been reduced significantly through the use of concrete matting (Zang et al. 1993; Evans and Stehn 1997). Dredged material has been used to create additional winter habitat (Evans and Stehn 1997).

Four captive flocks are producing offspring, and captive production has been sufficient to provide over 262 birds for the non-migratory reintroduction experiment in Florida since 1993. Another reintroduction using captive-produced young was started in 2001 in the eastern United States, with Wisconsin as the nesting area and western Florida as the wintering site.

There are no unique conflicts or logistical difficulties to achieving recovery that can be identified at the present time. There will, however, continue to be challenges of the type that impede new research and recovery techniques.

2.2 Recovery Goal

The overall recovery goal for the Whooping Crane is to protect, restore, and manage the species to be self-sustaining in the wild, no longer requiring the protections of the Species at Risk Act and the U.S.Endangered Species Act. The long-term recovery goal is to establish 1000 Whooping Cranes in North America by 2035.

Following successful implementation of this strategy, redesignation (downlisting) to threatened status would be recommended. Delisting criteria are not established in this strategy because a) the effective population size needed to ensure long-term survival of the species is not well established; and b) new threats are expected to arise before downlisting is achieved.

2.3 International Strategy for Recovery

The principal strategy of the International Recovery Plan for the Whooping Crane is to augment and increase the wild population by reducing threats and establishing two additional and discrete populations. Offspring from the captive breeding population will be released into the wild to establish the populations. Production by released birds and their offspring will ultimately result in self-sustaining wild populations. The continued growth of the AWBP and two additional populations will also curtail the loss of genetic diversity.

2.4 Recovery Criteria

Whooping cranes are listed as endangered by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC 2005). The cranes are listed under status criteria D1: very small population (IUCN 2001). This recovery strategy sets forth two criteria that, when attained, will ensure healthy, self-sustaining populations of Whooping Cranes in North America, such that the species is no longer in danger of extinction and can be redesignated as threatened in both Canada and the United States. The numerical goals for population size and stability can be achieved only if threats to the species' existence are sufficiently reduced or removed.

The following criteria must be met prior to redesignation (downlisting) of the Whooping Crane from endangered to threatened:

  1. Maintain a minimum of 40 productive pairs in the AWBP and establish a minimum of 25 productive pairs occurring in self-sustaining populations at each of two other discrete locations. A productive pair is defined as a pair that nests regularly and has fledged offspring. Population numbers would have to exceed 200 adults in the AWBP and 100 adults in each of the Florida non-migratory population and the eastern migratory population. Numerical objectives are based on a population viability assessment of what is needed to maintain genetic material for the population. All three populations must be self-sustaining for a decade at the designated levels before downlisting would be considered. Recovery actions may result in migratory and non-migratory populations as occurred historically in North America. If only one reintroduced population becomes self-sustaining, then the AWBP must remain above 400 individuals (i.e. 100 productive pairs) and the new population must remain above 120 individuals (i.e. 30 productive pairs), both populations must be self sustaining for a decade. If reintroduced populations do not become self-sustaining, then the AWBP must remain above 1000 individuals for a decade (i.e., 250 productive pairs). These higher numbers are needed because the AWBP currently has a very limited range in both summer and winter and could be severely impacted by a catastrophic event.
  2. Maintain a minimum of 153 Whooping Cranes in captivity (21 productive pairs) as a safeguard to ensure the long-term survival of the species. Genetic analysis demonstrates that these numbers can maintain 90% of the genetic material of the species for 100 years (Jones and Lacy 2003).

2.5 Recovery Objectives

Objective 1:    Continue to build the AWBP.The short-term recovery objective of 40 productive pairs in the AWBP for 10 consecutive years has been met. To reach the long-term recovery goal of 1000 birds in North America by the year 2035, the AWBP needs to increase to 240 individuals and 70 productive pairs by 2010.

Objective 2:    Develop and maintain captive populations. Increase the captive populations to 45 breeding pairs by 2010.

Objective 3:    Establish two additional wild populations by participating in the international effort to increase the FP to 100 individuals and 10 productive pairs by 2010 and establishing an eastern migratory population containing 80 adults by 2010.

Objective 4:    Determine the effective population size (Ne) for species survival. Analyze banding data and determine the Ne/N ratio for the AWBP.

Objective 5:    Maintain and expand information/education programs. Promote education on Whooping Crane recovery through innovative media technologies.

2.6 Research and Management Activities Needed

This section provides a general description of the research and management activities needed to meet the objectives. Action plan(s) will contain more detailed information on the actions and the implementation schedule. For more information on actions already completed or under way, the reader should refer to Appendix C in the International Recovery Plan.

1.   Continue to build the AWBP. Increase the AWBP to 240 individuals and 70 productive pairs by 2010 (Priority 1).

This will be achieved by reducing mortality and removing habitat constraints that might limit population recovery. The nesting and winter habitats appear to have the potential to support substantially more than the 58 nesting pairs and the associated subadults and young-of-the-year present in 2005 (Johns 1998; Tom Stehn pers. comm.).

Activities will include:

  • monitoring population numbers, including annual recruitment and mortality;
  • monitoring movements in migration;
  • reducing mortality through management actions;
  • restricting detrimental human activities; and
  • identifying, protecting, managing, and creating habitat.

2.   Develop and maintain captive populations. Increase the captive populations to 45 breeding pairs by 2010 (Priority 1).

Maintain 45 breeding pairs of Whooping Cranes at Patuxent Wildlife Research Center (15), International Crane Foundation (12), Calgary Zoo (10), Audubon Species Survival Center (5), and San Antonio Zoo (3). This will be achieved by examining the genetics of productive pairs in captivity and optimizing the production of Whooping Cranes in captivity using known methods.

Activities to achieve this objective include:

  • developing more sensitive measures of genetic diversity;
  • increasing the number of captive breeders;
  • refining avicultural methods and productivity; and
  • maintaining captive facilities.

3.   Establish two additional wild populations (Priority 2).

Continue research to identify appropriate reintroduction sites and improve reintroduction techniques. Protect and manage habitat of reintroduced populations. The U.S. Fish and Wildlife Service and the Canadian Wildlife Service should coordinate their research and management efforts to establish at least two discrete, self-sustaining populations, each consisting of a minimum of 25 nesting pairs by the year 2035.  By 2010, the FP should have 100 individuals and 10 pairs, and the eastern migratory population should have 80 adults.  As long as they meet recovery criteria, these new populations can be either migratory or non-migratory. Plans call for all releases to be in the eastern United States (Florida non-migratory population and eastern migratory population), at least through 2010.

Activities to meet this objective will include:

  • improving release techniques;
  • evaluating and selecting release sites;
  • establishing a non-migratory population; and
  • establishing a migratory population.

4.   Determine the effective population size (Ne) for species survival (Priority 3).

Continue to use genetic information to determine NE and revise recovery criteria as warranted. This NE will be based on advances in conservation biology, population viability theory, and on-the-ground recovery progress with other endangered species.

5.   Maintain and expand information/education programs (Priority 3).

Implement information and education programs to further recovery of the Whooping Crane. Issue press releases for December population counts at Aransas National Wildlife Refuge, spring departure from Aransas National Wildlife Refuge, spring arrival in Saskatchewan, requests for reports of migration sightings, number of nesting pairs in Wood Buffalo National Park, number of chicks surviving to autumn in and near Wood Buffalo National Park, autumn arrival in Saskatchewan and other provinces, and similar significant events for the FP and eastern migratory population. Provide outreach opportunistically at meetings and festivals.

Activities to meet this objective will include:

  • developing media products; and
  • providing viewing opportunities.

2.7 Broad Strategies to Address Threats

2.7.1 Habitat Loss and Degradation

Habitat destruction and curtailment of the species' range will be addressed through population and habitat monitoring on the breeding, migration, and wintering grounds; reduction of collision and disease mortality; public education to prevent accidental shooting; habitat protection and management; and monitoring and regulation of specific threats and impacts, such as chemical spills, coastal erosion, dredging, changing salinity from water withdrawal, and changes in in-stream flows. Establishment of two additional wild populations will also address this threat through augmentation of the current population and expansion of Whooping Crane range in historical habitats. Development and maintenance of a captive population will provide protection against extinction in the wild and produce birds for reintroduction to the wild.

Suitable breeding habitat currently unoccupied and areas important for migration will be identified using satellite imagery and historical use data. Protection of these sites will occur through cooperative agreements, existing legislation, and/or purchase.

Through consultation and management, stream flows should be maintained to continue productivity of bay systems used by wintering Whooping Cranes. Freshwater ponds will be maintained and new ponds will be created on wintering grounds to ensure a supply of fresh water for the cranes and to optimize distribution of upland use by cranes. Human activities on upland areas need to be controlled to minimize disturbance to cranes at freshwater sources.

2.7.2 Loss of Genetic Diversity

The loss of genetic diversity can be overcome only as population numbers increase to the level where the creation of new alleles through mutation will offset past, current, and future losses in genetic diversity. The managers of the captive population should make annual analyses of the genetics and demographics of captive populations. Frozen semen banks should be maintained to prevent loss of founder lines, and the number of captive breeders should be increased.

2.7.3 Disturbance

To protect cranes from disturbance, human activities should be monitored, regulated, and/or prohibited wherever they have the potential to cause problems for the cranes. For example, construction periods should be restricted to times when cranes are absent, and the altitude of aircraft over nesting and wintering areas should be regulated.

2.7.4 Collisions with Power Lines

To address the threat of power lines, actions will be developed to minimize losses, such as increasing the visibility of structures or lines.

2.7.5 Chemical Spills

Environment Canada, Fisheries and Oceans Canada, and the equivalent provincial/territorial agencies share lead responsibility for spill response within their respective jurisdictions. Parks Canada Agency is the lead for situations within Wood Buffalo National Park. In the United States, the U.S. Coast Guard has the lead responsibility for spill response and containment, and the U.S. Fish and Wildlife Service has response plans for the Gulf of Mexico (U.S. Fish and Wildlife Service 1979) and specifically for Aransas National Wildlife Refuge (Robertson et al. 1993). Appropriate agencies will be encouraged to inspect oil and gas facilities.

2.7.6 Disease and Parasites

To address the threat of disease and parasites, methods of disease prevention, detection, and treatment will be developed. In captive centres, research should be conducted on diagnosis and treatment of cranes to ensure flock health. As well, routine health practices will be monitored at captive facilities.

2.7.7 Predation

Predator control is not considered an appropriate management technique within Canadian national parks. Efforts must be taken to reduce predation where practical, especially in the reintroduced populations. This will be done by determining mortality factors, measuring impacts, and carrying out strategies to reduce losses. In addition, release techniques will be developed to identify methods for teaching predator avoidance to birds.

2.7.8 Shooting

Continued education and enforcement will be needed to ensure that hunting does not present a threat to the Whooping Crane.

2.8 Critical Habitat

Critical habitat is defined in the Species at Risk Actas “the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species' critical habitat in a recovery strategy or in an action plan for the species” (Subsection 2(1)). In this recovery strategy we identify areas of critical habitat on the breeding grounds within Wood Buffalo National Park previously described under Wood Buffalo National Park Game Regulations.

2.8.1 Breeding Grounds

The Canadian Wildlife Service has been monitoring Whooping Crane nesting activity in Canada since 1954. The majority of currently occupied breeding territories (91%) are located within Wood Buffalo National Park. Whooping Cranes are slow to pioneer new areas, and most (76%) of the pairs establish territories within 20 km of their natal area (Johns et al. 2005).

Boreal marsh complexes that meet the requirements outlined in Timoney (1999) can be deemed as essential for Whooping Cranes to establish territories, build nests, and raise their young. Timoney (1999) describes nesting wetlands as visually open patchy wetland complexes containing semi-permanent and permanent wetlands with water depths averaging 25 cm; this diverse mosaic of wetlands contains a high proportion of bulrush marsh associated with mixed marsh (sedge and cattail), shrubby marsh (willow and birch) and diatomaceous ponds with bulrush. The quantity of suitable habitat identified as the whooping crane nesting area within the boundaries of Wood Buffalo National Park appears to be sufficient to support a growing population of Whooping Cranes (Olson and Olson Planning & Design Consultants Inc. 2003; Tischendorf 2003).

Proposed critical habitat identified in this recovery strategy is therefore:
Boreal marsh complexes surrounded by a 100 meter riparian management zone (Thorpe 2005) in that portion of the northeast corner of Wood Buffalo National Park that meet the requirements outlined in Timoney (1999) within the whooping crane nesting area as described in SCHEDULE I - Wood Buffalo National Park Game Regulations SOR/78-830 (see below).

“The whooping crane nesting area lies within the following boundaries:


Commencing at a point one mile west on Northwest Territories Highway No. 5 from the crossing of said highway across the Little Buffalo River and 180 metres north of the edge of the cleared right-of-way of said highway, thence in a north westerly direction parallel to said highway to a point 180 metres east of the centre of the main channel of the Nyarling River; thence in a north easterly direction parallel to the centre of the main channel of the Nyarling River to its intersection with a line drawn 180 metres west of and parallel to the centre of the main channel of the Little Buffalo River; thence in a south easterly direction parallel to and 180 metres west of the centre of the main channel of the Little Buffalo River to the centre of the main channel of Seton Creek; thence in a south westerly direction following the centre of the main channel of Seton Creek to a point due North of the commencement point; thence due South to the commencement point.


Commencing at a point due south of the most south easterly corner of the whooping crane nesting area described in Part A of this Schedule and 180 metres south of the edge of the cleared right-of-way of the Northwest Territory Highway No. 5; thence in a north westerly direction parallel to the said highway to a point due north of the most northerly extension of Sass Lake and 180 metres south of the cleared right-of-way of the said highway; thence due south to the most northerly extension of Sass Lake; thence in a south easterly direction along the shore of Sass Lake to the most easterly extension of Sass Lake, thence in a south easterly direction to a point 180 metres north of the centre line of the tributary of the Little Buffalo River; thence in a north easterly direction parallel to the centre line of the said tributary and 180 metres north of the said centre line to a point 180 metres west of the centre line of the Little Buffalo River; thence in a north westerly direction parallel to the centre line of the Little Buffalo River and 180 metres west to the commencement point.”

Activities likely to result in destruction of breeding critical habitat

Destruction of critical habitat for the Whooping Crane in Canada is any alteration to the topography, geology, soil conditions, vegetation, chemical composition of air or water, surface water or groundwater hydrology and microclimate of such a magnitude, intensity, or duration that significantly reduces the capacity of the critical habitat to contribute to the survival or recovery of this species.

Examples of activities that are likely to result in destruction of critical habitat for breeding include, but are not limited to, radical or lasting alterations to normal hydrological regimes, infrastructure development (e.g. power lines, towers, roads), plus a number of activities related to forestry practices, mining, oil and gas exploration (e.g. application of pesticides, construction of roads, access and resource extraction).

Protection of breeding habitat

Wood Buffalo National Park is protected under the Canada National Parks Act. To afford the highest level of protection, the breeding habitat is designated as a Zone 1 Special Preservation area. The Special Preservation designation establishes that there are to be no human made facilities (except Highway 5) within the area, and human access is prohibited from April 15 through October, except for park staff and scientists involved in Whooping Crane research. The breeding grounds are also designated as a Wetland of International Importance by the Ramsar Convention and an Important Bird Area by BirdLife International. Because of these designations, the proposed critical habitat is protected from a number of anthropogenic threats.

2.8.2 Schedule of Studies to Identify Additional Critical Habitat

Identification of additional areas as critical habitat (e.g., unoccupied potential breeding grounds outside of Wood Buffalo National Park and migration staging areas) will be considered following completion of all or part of the schedule of studies below. The identification of additional critical habitat will take place after consultations are completed with landowners and other directly affected parties including numerous aboriginal organizations; to enable consultations, land tenure must be determined. Consultations will also investigate suitable protection options for the critical habitat being considered.

Breeding Habitat

The growth rate of the population may be significantly increased as cranes spread to suitable habitat outside the boundaries of the nesting area as described above (Tischendorf 2003). The Canadian Wildlife Service and Parks Canada have investigated suitable unoccupied nesting habitat within Wood Buffalo National Park and adjacent areas that may be necessary for the recovery of Whooping Cranes (Olson and Olson 2003).  This research indicates that expansion of the Aransas/Wood Buffalo Population will likely lead to more breeding of Whooping Cranes outside of the current Whooping Crane nesting area delineated above. In addition, expansion outside of Wood Buffalo National Park, into adjacent, currently unprotected areas of the Northwest Territories (Olson and Olson 2003) is also anticipated. Combined, the amount of suitable breeding habitat available within the park and the amount of suitable breeding habitat available adjacent to the northeast corner of the park appears to be enough to support a population of upwards of 250 breeding pairs and 1000 individuals, enough to meet recovery goals (Olson and Olson 2003). In recent years Whooping Cranes have begun expanding their breeding range into these new areas. Therefore, protecting all available suitable habitat is required to support the maximum possible growth rate for the Whooping Crane population. These additional areas may be identified as critical habitat in the future pending refinement of the precise areas and boundaries.

Protection of Potential Breeding Critical Habitat

Currently there is no formal protection for wetland habitat adjacent to the northeast corner of the park. This area is under the jurisdiction of the Government of the Northwest Territories, Indian and Northern Affairs Canada and the Salt River First Nation. Consultation with these organizations is required, as well as community consultations with all affected parties to present new critical habitat to be identified and to discuss the best protection options for this habitat (DeWandel 2003). Where appropriate, stewardship opportunities will be investigated with the appropriate land managers (DeWandel 2003). If these additional areas are identified as critical habitat in the future, we would need to protect those areas from the same kinds of activities identified above as being destruction.

Migration Habitat – Saskatchewan Staging Areas

During fall migration Whooping Cranes typically stop in south central Saskatchewan for several days or weeks. The area of Saskatchewan between Meadow Lake, Swift Current, Estevan and the Quill Lakes, can be described as a staging region for Whooping Cranes. The cranes spend their evenings roosting in shallow wetlands, while their days are occupied with feeding in harvested agricultural fields, chiefly wheat and barley fields (Johns et al. 1997). Fall staging wetlands are primarily on private lands (85%) (Johns et al. 1997). Few wetlands are used repeatedly from one year to the next since most staging wetlands are ephemeral and their availability to cranes fluctuates annually due to variations in precipitation. Preferred staging wetlands have the following characteristics: permanently (32%) or semi permanently (53%) flooded; soft mud bottoms (83%); almost any size from less than half a hectare to several thousand hectares; water depths at roost sites average 13 cm (SD 7.5); and roost sites are generally within 2 km of suitable feeding areas (agricultural fields) and are usually over 1 km from human habitation (Johns et al. 1997). Large wetlands with a secure water supply are important as staging sites since they provide refuge when ephemeral wetlands are dry.

Due to the ephemeral nature of most prairie wetlands and their inconsistent use by Whooping Cranes, it is difficult to predict which wetlands may be used by Whooping Cranes at any particular time. However, wetland complexes that meet the criteria listed in Johns et al. (1997) and/or exhibit repeated use by Whooping Cranes may be identified as critical habitat in the future.

Schedule of Studies
  1. Ongoing inventory of birds and habitat areas used (2007-2010).
  2. Define precise areas and boundaries of potential additional critical habitat for breeding in Canada (2008; see above).
  3. Finalize staging site selection criteria and apply criteria to potential critical habitat staging areas (2008; see above).
  4. Review and update critical habitat list (2010).

2.8.3 Critical Habitat – United States

Migration Habitat

In the United States critical migration habitat has been designated at four locations: the Platte River bottoms between Lexington and Denman, Nebraska; Cheyenne Bottoms State Waterfowl Management Area and Quivira National Wildlife Refuge, Kansas; and Salt Plains National Wildlife Refuge, Oklahoma. These locations were designated as critical habitat in 1978 under the authority of the United States Endangered Species Act (Fed. Reg. Vol. 43, Number 94, May 15, U.S. Fish and Wildlife Service 1994).

Wintering Grounds

Portions of the Aransas National Wildlife Refuge and vicinity, Texas have been designated as critical habitat for the Whooping Crane in 1978 under the authority of United States Endangered Species Act (Fed. Reg. Vol. 43, Number 94, May 15, U.S. Fish and Wildlife Service 1994).

Additional information on critical habitat and its protection in the United States can be found in the International Recovery Plan.

2.9 Action Plan Timeline

The Canadian action plan for the Whooping Crane will be completed by June 2008.

2.10 Evaluation of Recovery Activities

The Canada/United States International Whooping Crane Recovery Team continually evaluates recovery activities, their direction, and the methodology used for each. In addition, outside agencies are asked to periodically evaluate various aspects of the recovery program to ensure that recovery activities are consistent with recovery guidelines outlined in the International Recovery Plan for the Whooping Crane, the Recovery Strategy for the Whooping Crane in Canada, and the Canada/U.S. Memorandum of Understanding on the Conservation of the Whooping Crane. These actions are undertaken under the authority of the Species at Risk Act (Section 49(d)).

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