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Protocol for conditioning costume-reared Whooping cranes to follow an ultralight aircraft in migration


Operation Migration and USGS Patuxent Wildlife Research Center with assistance from other members of the Whooping Crane Eastern Partnership (WCEP) propose the following guidelines for costume-rearing, aircraft conditioning, translocation, flight conditioning, migration and subsequent release of Whooping cranes as required for the reintroduction program.

This protocol will guide activities for the use of ultralight aircraft for the release of Whooping cranes into eastern North America.


Whooping cranes introduced into an eastern habitat will not have the benefit of wild conspecifics to teach them wild behavior; particularly human avoidance.  Without this advantage it becomes more difficult to produce birds that will follow the aircraft, yet behave like wild birds once released.  Past studies indicate that in order to rear birds that are not tame we must minimize human influence and provide as natural an experience as possible. We must replicate the natural rearing process by providing the birds with proper sexual imprint models and raise them in small groups Acting a surrogate parents our ability to teach wildness is severely limited. Because we can only teach the bare minimum in human avoidance, we need to exploit their natural fear of the unfamiliar and ensure that all things human remain foreign. Ideally, the birds should be released on the wintering grounds without having encountered un-costumed people and/or human voices.  Efforts should be made to improve the efficiency of the flight conditioning and to reduce even costumed human contact during the training period. 

Human contact should be defined as the presence of the human form, including costumed handlers; the sounds of human activity, including voices and the presence of man-made environments and equipage. As well, human activities like carrying of feed containers and other equipment while in costume should be minimized. All equipment needed for training and bird care (radios, cameras, recording devices and medical bags) should be disguised, covered or hidden while in the presence of the birds.

Facilities and Caretaking

Isolation rearing will be performed in accordance to the USGS Patuxent WRC Protocol for Hand-rearing Crane Chicks. Specific details relevant to ultralight conditioned cranes are included in this document. 

      • Conspecific adult imprinting models will be penned in the aviary and will have access to the sand runs that are perpendicular to the aviary runs used by the chicks.  While the chicks are being exposed to the running aircraft, these adults will be locked inside and observed for tolerance to the disturbance.
      • Costumes, designed to disguise the human form, will be supplied by OM and used in conjunction with hand held puppets of adult crane heads and recordings of crane calls.  Sleeve cuffs or gloves will cover the handler’s hands when working with the cranes. Handlers should make an effort to wear the same footwear.
      • At the discretion of the medical staff gloves will be removed in order to properly treat or examine the chicks.
      • Patuxent has provided several plastic Whooping crane decoys. They will be kept in the pens with the birds throughout their captive period so they become familiar with these objects. Later this familiarity can be used to encourage the birds to roost in water at the wintering site.
      • Absolutely NO TALKING will be tolerated within earshot of the birds. If communication is absolutely necessary, notes could be used.  If this is not practical, team members will move away from the birds or, as a last resort, whisper very quietly in to the ear of the other team member. 
      • Absolutely no feeding will be done from hand. All food used as an incentive will be dispensed by methods other than hand tossing. Mealworms or other treats will be pointed out using a puppet to encourage foraging.
      • The colts will be shielded from observing caretaking activities such as pen cleaning and food/water changes as much as practical. 
      • As much as practical the birds will be visually shielded from manmade structures and equipment. Efforts will be made to disguise the propagation building and surrounding areasin order to provide a more natural environment.
      • The number of handlers will be kept to a minimum during conditioning to reduce the amount of human contact, improve handler safety and to minimize distractions.
      • Recorded wetland sounds will be played inside the aviary to create a natural environment and mask outside human noise
      • The colts will be moved from the propagation building to the large pond pens known as the “White Series” when the caretaking staff agree that weather conditions, socialization and ages are appropriate. Heat lamps and additional sheltermay be provided as needed.
      • The birds will be socialized in small cohorts based on age and compatibility.
      • The duration and frequency of aircraft training will be based on the response of the chicks.  Each training session will be evaluated for success and if the chicks are responding positively, additional training may be curtailed temporarily to limit unnecessary human contact.
      • To reinforce the “follow the aircraft” response, efforts will be made to minimize the number of times a chick is led by a walking handler. However, during early conditioning, it may be safer to lead chicks to the aircraft rather than to carry them.
      • Additional exercise beyond the needs of the training schedule may be necessary during the early development of the birds and will be conducted at the discretion of the handlers.  
      • No human avoidance conditioning (HAC) will be attempted prior to the release of these birds.
      • The birds will be handled and examined in costume.  If medical or other procedures require the removal of the facemask, the chicks will be hooded or protected from seeing the handlers. The trikes used for this training are registered aircraft and operated under strict federal regulations. Although they are not capable of flight with the wing removed they are still considered aircraft and can only be operated by qualified persons.
      • The wing will be removed from the aircraft to conduct the preliminary training allowing the handlers to more easily manoeuvre it close to the propagation building. Conditioning the birds to the wing once they have been moved to Necedah NWR normally takes approximately several days. To smooth this transition we will use a small collapsible, imitation wing with a 10 ft span during the preliminary training.
      • Dr. Bernhard Wessling has provided the project with digital crane calls. These files have been downloaded onto MP3 players or similar devices. There are up to six adult crane calls that handlers can use to communicate with the colts.  Only pilots and qualified handlers will use the vocalizers to broadcast any calls other than the brood/contact call.

Conditioning colts to follow aircraft:

Phase 1
Tape recordings of the aircraft engine sounds and recorded brood callswill be played severaltimes daily to pre-hatching eggs and newly hatched chicks.

Phase 2
When chicks are old enough to go outdoors, they will be introduced to the real aircraft for the first time.  A smaller imitation wing will be fitted, allowing the trike to be parked outside their sand runs and the engine will be revved periodically during the day.  The duration of the exercise and the chick’s response to the aircraft will be recorded on data forms. Note: Due to the air-cooled, two-stroke configuration of the aircraft engine it should not be allowed to idle of long periods and should never be left unattended.

Phase 3
A small portable pen (ca 2-3 ft. in diameter and 2 ft. high) may be used to provide the chicks with their next level of exposure to the aircraft. The aircraft will be positioned beside this enclosure and the chicks will be encouraged to forage for mealworms, pointed out using the puppet head, while the engine is revved.  Time and responses will be recorded on data forms. 
Note: Phase 2 and Phase 3 procedures may be combined, used in reverse orders or one or the other may be eliminated based on the development of the chick, at the discretion of the handlers.

Phase 4
When the chicks show little anxiety at the sound of the engine or the movement of the aircraft, they will advance to this level of conditioning This will be conducted in a circular pen ca 30 ft. in diameter and 2 ft. high. The colts will be carried, or led to, and placed in the pen. One handler will taxi the wingless aircraft around the outside perimeter, stopping periodically to point out mealworms using the puppet head mounted to an extension arm. The pilot will extend the puppet head over the chick fencing from the cockpit to interact with the colts.  A few colts may be worked together if they will tolerate each other and the trainer can safely handle them.  Multiple colts need close observation for possible anxiety e.g. a colt may not follow because it is afraid of another colt, rather than the trike.  A smaller circular pen, in which to temporarily place problem colts during training, may be constructed in the centre of the 30 ft. pen.  This may function as a “jealousy pen” allowing reluctant colts the opportunity to observe others foraging for treats with the aircraft parent. The duration of confinement is discretionary and based on behaviour.  Observations, chick response and training times will be recorded on data forms.

Phase 5
As the cranes grow tall enough to be protected by the propeller guard fitted to the aircraft, they will begin to follow the trike directly from the aviary or from the White Series pens to the adjacent field. A two foot high plastic fence running the length of the field may be used to protect the chicks from the wheel and propeller. The aircraft could taxi down one side with the chicks on the other. Birds who tolerate each other may be worked together in small groups.  The trips will progress in length and include rewards such as mealworms, crickets or pond exposureto reinforce a positive response. The duration of each exposure and the chicks’ response to the aircraft will be recorded ondata sheets.

Prior to fledging, the birds will be transported to the introduction site in Wisconsin. They will be shipped in accordance with Patuxent Wildlife Research Center’s Protocol For Transporting Cranes, in individual containers supplied by OM. The shipment will be conducted by private aircraft from a departure airport as close to Patuxent as practical to reduce the amount of ground travel needed. Based on the age difference of the birds this transfer to the introduction site may be accomplished in two or more shipments

Medical Examination
The birds will be transported, in air-conditioned vans from the Necedah Airport to the Necedah National Wildlife Refuge. Prior to loading into the vans the birds will be check to ensure they are standing in their containers. This transfer will be performed without talking and as quickly as is practical. As soon as possible, the birds will be released into the appropriate cohort pens and monitored for signs of stress. A member of the WCEP Health Team will attend this transfer and release.  

Pens and Enclosures
Four isolated pens and training areas exist at Necedah NWR to house the Whooping crane chicks. Each site consists of a smaller, high security pen constructed on dry land to contain the birds and is referred to as the dry pen. The outside surface is fully clad to provide a visual barrier. Additionally, there is a larger, more open enclosure built into the marsh to provide a foraging and roosting area for the birds. This area is referred to as the wet pen.  Adjacent these enclosures are aircraft operating areas for training. The four sites are named East, West and North based on their location around East Rynearson Pond at Necedah NWR plus the new Canfield Site to the north west.

      • The East Site has been modified to accommodate a larger number of birds, giving us more options when it is time to socialize the separate cohorts.
      • A permanent blind has been constructed at the East Site to allow observation by the team and others.
      • As often as practical the birds will be allowed access to the wet pen at night to promote water roosting.
      • Solar powered pumps will be used to create a steady flow of fresh water within the dry pens. Other methods of providing fresh water will be used during long periods of overcast or if the pumps fail to operate properly.
      • The pens will be cleaned daily to remove spilled food and excessive amounts of fecal material.  
      • Occasionally it is necessary to move the birds away from the pen in order to perform routine maintenance like cutting the grass on the aircraft training areas. In the past we have walked the birds through high brush and forested areas to hold them in wetlands. This may condition them to tall grass habitat where predation is more likely. Prior to the arrival of the birds at Necedah, wide paths leading to the holding areas will be cleared so the birds will not be introduced to improper habitat.
      • Electric fencer units will be used to protect all pens.

Conditioning fledglings to follow aircraft

      • Flight conditioning will begin once the birds have had a day or two to recover from shipping. Initially, the training will continue using the trike only. Later the wing will be attached to the aircraft and several days will be spent familiarizing the birds to the new shape. 
      • Similar to the procedures at Patuxent, the duration and frequency of aircraft training will be based on the response of the chicks.  Each training session will be evaluated for success and if the chicks are responding positively, additional training may be curtailed temporarily to limit unnecessary human contact.
      • The number of handlers will be kept to a minimum during conditioning to reduce the human contact, improve handler safety, and to minimize distractions. Only authorized handlers will have access to the birds and training area.
      • The birds may be released to forage on their own in the wetlands near their pens. This will allow them time away from human contact and to establish their natural dominance structure both in the air and on the ground and to experience a more natural environment. This will be done at the discretion of the handlers and when the birds are older and during the day when the chance of predation is minimized.
      • During extended periods of poor flying weather the birds will be released for exercise without the aircraft. This should be done every three days based on weather and other conditions. 
      • When the team is confident about the security of the pens and the birds are old enough, they will be moved to the top-netted wet pen during the night. This will provide them with an opportunity to water roost. Early in the morning the birds may be moved to the dry pen in preparation for flight training.
      • Food may be withheld during the night to discourage the birds from leaving the roost to feed and to assist in management. This will be at the discretion of the team and balanced against the birds’ need for proper nutrition. 
      • Once each group is able to follow the aircraft in the air as a cohesive unit, the three cohorts will be introduced. The mixed groups will be allowed to forage outside the pen together allowing them time to socialize. They will be monitored for aggression, which will be prevented if necessary. At night they will be housed in separate sections of the dry or wet pen allowing them visual contact with each other. Once the aggressive encounters have reduced until there is little danger of injury, the divider will be removed and the birds will be treated as one cohort.
      • The team will observe the behavior of the birds to determine and record the dominance order within the flock.
      • The duration of each exercise, and the birds’ response, will be recorded on data forms. Data will also be collected on flight order and weather conditions including temperature, dew point, winds and density altitude as the situation allows. 
      • Prior to migration the team will encourage the birds to land in water at the end of flight training sessions to prepare them for the arrival at the final site where the aircraft cannot land.
      • Prior to departure the team will house the birds overnight at least once in the portable pen to condition them to the enclosures used during migration.

Medical Examination
Prior to departing the introduction site, the Medical Team will again examine the birds. This procedure is unavoidably disruptive to the birds and temporarily affects their relationship with the handlers and aircraft. For this reason the Medical Team will conduct this examination well before the expected migration departure date to allow the handlers to regain the confidence of the birds. The Medical Team will provide the protocol for this examination and will conduct all work in silence with the birds hooded.

Radio Tracking 
While the birds are being handled for the medical examination, they will also be fitted with tracking devices and marked bands. This procedure will comply with the guidelines of the North American Bird Banding Manual and Animal Care and Use Committee guidelines and the recommendations of the Recovery Team  (see Monitoring Protocol)


      • The start of the migration will be dictated by the endurance of the birds, their social compatibility and the readiness of the crew. The field team will allow as much lead-time as possible before setting a target departure date. Thereafter, the team will be prepared and the actual start date will be dependant on the weather.
      • Visual barrier panels may be necessary on the travel pen to control what the birds are able to see. These fabric-covered panels are susceptible to high winds but have been designed to be detachable. They can be set up a distance from the pen and removed in the event of high winds.   
      • A second travel pen and travel pen trailer is used during the migration allowing the team to leapfrog ahead of the flight crew. By the time the birds leave one stopover site, a pen will already be in place at the next location. This reduces the amount of time the flight crew must hold the birds at the new location waiting for the pen to be dismantled, moved and re-assembled. Often during this holding period we had to lead the birds through inappropriate habitat to find isolated areas to wait for the ground crew. This may inadvertently acclimate the birds to forest and tall grass habitat where predators are more common.
      • During previous migrations we found that we were able to perform “air pick ups”. Rather than land the aircraft next to the pen and begin the take off roll as the birds were released, the ground crew released them as the lead pilot flew past the pen at low altitude and slow speed. The birds soon became practiced at anticipating the timing and direction of departure and were able to catch the aircraft after only a short distance. During the training season at Necedah NWR we will attempt to condition the birds to land next to costumed handlers at pre-selected site where the aircraft cannot land. These “air drops” combined with “air pick ups” may enable us to select stopover sites on the migration that are more isolated.
      • There are times when it is not possible to find isolated areas that allow for an adequate distance between the bird pen and the migration crew camp. In this situation the field team will determine if it is necessary to move the majority of the camp to another location.  
      • Most of the landing sites are privately owned and the migration crew is large. We must make every effort to reduce the impact we have on the landowners so as to not abuse their hospitality.
      • A protocol will be developed to move the travel pens if the migration team is unable to progress due to long weather delays. This procedure will help reduce the threat of bacteria build up within the enclosure during prolongs stays at one location.


Daily pen check schedule and duties 
Birds will be checked twice each day; once in the morning and once in the evening for the entire duration of their stay. The evening check will last until all birds are roosting in a safe location.

Juveniles will usually be in the large, open-topped pen. They may be temporarily enclosed in the top-netted pen as minimally necessary to reduce management problems caused by presence of older birds, predators and/or other threats.

If a storm or high tides are predicted, the chicks will be released even if older birds are present however the food should be removed.

If the older birds are in the area and do not leave after several days, the chicks will be let out for supervised exercise while the older birds are present. This should occur at least every three days, weather permitting and at least two handlers will be present. If the chicks are eventually socialized and left out with older birds, extra feeders may be needed to keep the older birds from dominating the feeding station.  Additional new techniques, e.g., the laser gun, may be tried to encourage the older birds to leave the area. The use of any discouragement techniques will be coordinated through the team leaders       

During evening checks, make sure that all birds are in the pen or in a safe location at roost time and record the final roost location of all birds. If the birds are not in the pen at roost time, first try to call them back to the pen with the loudspeaker from the blind. If the birds do not return, costumed handlers should enter the pen with the loudspeaker and attempt to call in the birds. If the birds do not respond, the costumed caretakers should walk to the birds and then lead or herd them back to the pen. If the birds are in unsafe roosting conditions and will not return to the pen, other method such as the swamp monster, air horns or an ATV may be used to flush them from the unsafe area. There is a significant population of bobcats at St Marks NWR. An experienced trapper has recommended that roosting within the pen and a secure electric fencer are the best ways to safeguard the birds.

During the early part of the winter, pen checks will be conducted by two people. This could be reduced to one person as the birds begin to follow a routine and all personnel are familiar with the procedures.

Upon arriving at the blind, count the birds as many times as necessary to ensure an accurate count.

Check the radio signal of each chick to assess transmitter performance. Immediately inform the WCEP Tracking Team if any of transmitters have failed. Also scan frequencies of older and DAR Whooping cranes to check for their presence in the area. If any are detected, inform Tracking Team staff.

Add food to feeders as needed. Remove wet food and clean and dry feeders. Regularly return feeders to camp for cleaning and disinfecting. Clean spilt food under feeders and remove any mold. Bag and remove any wet, dirty or contaminated food from the area as to not attract predators.

Visually examine all birds to evaluate their health and behavior and record anything unusual. 

Check the pump system, solar panels and backup gravity-feed water system. 

If traps are being run, check and reset them if they have been sprung. If live chickens are being used, feed and water them each day. If a bobcat is caught, call refuge staff. If another species is caught (e.g., a raccoon), remove it from the area for release and reset the trap.

Check the perimeter fence daily for breaks and conductivity of electric fencer. Ensure the electric fencer is turned on before leaving the pen and test with a fencer meter or other method to be certain there is adequate output. Regularly use a meter to check the fencer at intervals from the power source. Watch for a drop in voltage, identify the problem and make the needed repairs as soon as possible. Always check the entire fence after a high tide or a storm event when vegetation could have collected to short out the fencer wire.

Lock both blinds before leaving the pensite.

Ensure that there is a first aid kit in the blind at all times for both people and birds. Keep blinds clean and organized.

Staff checking the birds will ensure they can communicate with other team members at all times by cell phone or other method. Ensure that cell phones are muted when near the birds. A list of veterinarians will be posted in the blind, at camp and in all project cell phones.  Phone numbers for refuge staff and management (including home numbers where possible) will be posted and listed in all project cell phones.

Weather Monitoring 
The weather will be monitored each day using the OM high speed satellite to link to several reliable weather sites that we use to determine current conditions and predict trends. Additionally monitoring staff traveling to the pensite will carry a handheld VHF transceiver. Weather will be checked prior to each trip to the pensite, and special attention will be paid to predictions for overnight weather. If severe storms that include lightning, coastal flooding, and/or strong winds are predicted, the juveniles will not be enclosed in the top-netted pen even if older birds are present at the pensite.   

Data collection 
Daily records will be kept for all bird activity and pensite conditions.  One copy will be left in the blind and a second will be returned to the camp for safe keeping. Two data sheets will be completed each day. These records will be transcribed into a Word document by the end of the winter season and made available to WCEP partners. This document will include a cover sheet that quantifies any measurements used, qualifies any estimates given, defines acronyms and abbreviations and provides the location of any geographic feature referred to in the data sheets or notes. 

A record of these data will be forwarded to the Monitoring Team weekly. Every Friday or other mutually agreeable day, a representative from the team at St. Marks and Chassahowitzka will discuss issues on a phone call. Both teams will report bi-weekly on the Bird Team Call.

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