Whooping Crane basic facts and management

by Chester McConnell, Friends of the Wild Whoopers

The Whooping Crane is the symbol of conservation in North America. Due to excellent cooperation between the United States and Canada, this endangered species is recovering from the brink of extinction. Their population increased from 16 individuals in 1941 to 588 wild and captive birds in September 2012. The name “Whooper” probably came from the loud, single-note call they make when disturbed.

ing crane in wetland.

Two adult whooping cranes in wetland.

The adult is 5 feet tall, the tallest bird in North America. When the wings are extended they are 7 feet from tip to tip. They are graceful flyers, elegant walkers, and picturesque dancers. Adults are a beautiful snowy white with black outer wing feathers visible when the wings are extended. The top of the head is red with a black cheek and back of neck, yellow eyes, and gray-black feet and legs.

Soft down covering the cute baby chicks is buff-brown. At about 40-days-of-age, cinnamon-brown feathers emerge. When they are one-year-old they have their white adult plumage.

Whooping crane Chick

Whooping Crane chick

Whooping cranes

Adult (left) and juvenile (right) whooping cranes.

 

Whooping Crane Migration Map

Whooping Crane current and former range and migration corridors.

They begin pairing when 2 or 3 years old. Courtship involves dancing together and a duet called the Unison Call. Whooping Cranes mate for life. Females begin producing eggs at age 4 and generally produce two eggs each year. Usually only one chick survives. The pair returns to the same area each spring and chases other cranes from their nesting area that is called a “territory”. It may include a square mile or a larger area. Chasing other cranes away ensures there will be enough food for them and their chick. At night they stand in shallow water where they are safer from danger.

They build a nest in a shallow wetland, often on a shallow-water island. The large nest contains plants that grow in the water (sedges, bulrush, and cattail) and may measure 4 feet across and 8 to 18 inches high. The parents take turns keeping the eggs warm and they hatch in about 30 days. The two eggs are laid one to two days apart so one chick emerges before the other. They can walk and swim short distances within a few hours after hatching and may leave the nest when a day old. The chicks grow rapidly. They are called “colts” because they have long legs and seem to gallop when they run. In summer, Whooping Cranes eat minnows, frogs, insects, plant tubers, crayfish, snails, mice, voles, and other baby birds. They are good fliers by the time they are 80 days of age. In September-October they retrace their migration pathway to escape winter snows and reach the warm Texas coast. During migration they stop periodically to rest and feed on barley and wheat seeds that have fallen to the ground when farmers harvested their fields.

In Texas they live in shallow marshes, bays, and tidal flats. They return to the same area each winter and defend their “territory” by chasing away other cranes. The territory may contain 150 to 300 acres. Winter foods are primarily blue crabs and soft-shelled clams but include shrimp, eels, snakes, cranberries, minnows, crayfish, acorns, and roots.

An individual bird may live as long as 25 years. But, Whooping Cranes face many dangers in the wild. Coyotes, wolves, bobcats, and golden eagles kill adult cranes. Bears, ravens, and crows eat eggs and mink eat crane chicks. When they are flying in storms or poor light they sometimes crash into power lines. And they die of several types of diseases.

In addition to the single self-sustaining population there are birds in captivity at seven locations and three other populations began as experiments to try to ensure that Whooping Cranes survive in the wild. There are 160 cranes in captivity including 23 young. Most of the young are released into the wild as part of the three experiments. In the first experiment, begun in 1993, juvenile captive-reared cranes were released in the Kissimmee Prairie of central Florida. Additional young cranes were released there each year. This is a cooperative effort by U.S. and Canadian federal agencies, the state of Florida and the private sector, to start a population that does not face the hazards of migration. Cranes learn a migration route from their parents. These cranes were raised in captivity so they did not learn to migrate. There were 12 cranes in this flock in 2016.

Whooping Cranes

Whoopers learning their migration route by following an ultra-lite aircraft

In 1997, Kent Clegg was the first individual to teach captive-reared Whooping Cranes to fly and follow a small aircraft.  He led them in an 800-mile migration in the western United States.  His technique was then used in the second experiment beginning in 200l to establish a population that nests in Wisconsin and migrates to western Florida. U.S. and Canadian federal agencies, provincial and state governments, Operation Migration, Inc., and other private sector groups were cooperating in this experiment. This experiment was halted in 2015 because the adults did not have parenting skills and did not produce ample numbers of chicks to establish another flock. Another non-migratory flock with 20 whooping cranes was established in Louisiana in 2011. We are watching this new flock in hopes it is successful.

 

***** FOTWW’s mission is to help preserve and protect the Aransas/Wood Buffalo
population of wild whooping cranes and their habitat. *****

Friends of the Wild Whoopers is a nonprofit 501(c)3 organization.

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friendsofthewildwhoopers.org

Debate about counting Whooping Cranes continues

by Friends of the Wild Whoopers

Not all Whooping Cranes counted

Whooping Cranes

Whooping Cranes over Aransas NWR.  Photo by Kevin Sims ©2105

 

Aransas Wildlife Refuge biologist Tom Stehn conducted Whooping Crane census flights for 29 years at Aransas during which he tried to find every crane.  When Tom Stehn retired from U.S. Fish and Wildlife Service (USFWS) in 2011, the agency changed from doing a weekly Whooping Crane census to conducting a survey that takes place for roughly one week every December.  The change to a survey incorporated a technique called distance sampling where not every crane is counted but estimates of the cranes not seen are based on how far observed cranes were from the aircraft when sighted.  This statistically-derived method provides 95% confidence limits for an estimated Whooping Crane population.  Unfortunately, those confidence limits are quite large, equaling plus or minus 39 cranes out of an estimated flock of 338 during the winter of 2016.

Monitoring Whooping Cranes, Comparison article published

Dr. Bruce Pugesek and Tom Stehn, in January, 2017 published an article in the Proceedings of the 13th North American Crane Workshop entitled “THE UTILITY OF CENSUS OR SURVEY FOR MONITORING WHOOPING CRANES IN WINTER”.  The article compares the survey and census methods of counting Whooping Cranes.  An abstract for this paper is provided below, along with a link to download the entire 10-page article.

Tom Stehn commented to Friends of the Wild Whoopers about the article as follows:

“The article is not an easy read, but that’s the way science sometimes works.  It is a rebuttal of some of the things that USFWS wrote regarding their crane survey method.  In the article, Dr. Pugesek and I point out problems with the survey, including statistics, as well as what we consider as some of the “falsehoods” contained in what was written trying to justify the survey instituted after I retired.  I feel the USFWS was overly critical with unfair and overstated criticism of the census method that USFWS had done for 60 years.  And I firmly believe that with very thorough coverage of the crane area combined with the knowledge I had of individual cranes and their territories accumulated over 29 years of work and over 400 census flights, I could estimate the size of the whooping crane population in a manner much more accurately, and with a justifiable estimate of winter mortality, than what is being done on the current survey method.  The bottom line is that a census is usually stronger scientifically than a survey if the species’ biological parameters allow a census to be conducted.”

Tom continues: “If current USFWS policy requires that a survey with confidence limits be continued, I recommend that after the annual survey is completed, that additional funds be spent doing a census in a manner similar to what I used to do.  Doing some additional flying will allow comparison of the former census method with the current survey results which will provide more information about the crane population as well as better assess the survey methodology currently being employed.  A census would involve thorough coverage of the crane range with transects no more than 500 meters apart.  If there are now more cranes and a bigger area to cover, do the census over 1.5 days if need be.  Also, territories of all family groups should be determined, with a follow-up flight or two in early March to show which juveniles have died during the winter.  This estimate of annual winter mortality is very important, given what is known about drought and reduced inflows related to increased whooper mortality.”

ABSTRACT:

THE UTILITY OF CENSUS OR SURVEY FOR MONITORING WHOOPING CRANES IN WINTER
BRUCE H. PUGESEK,
1 Department of Ecology, Montana State University, Bozeman, MT 59717, USA
THOMAS V. STEHN, 1613 South Saunders Street, Aransas Pass, TX 78336, USA

Abstract: We discuss recent changes in the monitoring program for endangered whooping cranes (Grus americana) on their winter habitat in Texas. A 61-year annual census was replaced in the winter of 2011-2012 with a distance sampling procedure. Justification for the change was, in part, based on criticism of the previous methods of counting cranes and the assessment of crane mortality on the wintering grounds. We argue here that the arguments, methods, and analyses employed to discount the census procedure and mortality estimates were applied incorrectly or with flawed logic and assertions. We provide analysis and logical arguments to show that the census and mortality counts were scientifically valid estimates. The distance sampling protocol currently employed does not provide the accuracy needed to show small annual changes in population size, nor does it provide any estimate of winter mortality. Implications of the relative merit of census and mortality counts versus distance sampling surveys are discussed in the context of management of the whooping crane.

Link to article

***** FOTWW’s mission is to help preserve and protect the Aransas/Wood Buffalo
population of wild whooping cranes and their habitat. *****

Friends of the Wild Whoopers is a nonprofit 501(c)3 organization.

wind farm

friendsofthewildwhoopers.org