How do we condition the young Whooping cranes to accept and follow the aircraft?
Protocol for conditioning costume-reared Whooping cranes to follow an ultralight aircraft in migration
Since its inception, Operation Migration (OM) has endeavored to improve a technique it first developed in 1988, designed to teach a migratory route to endangered, precocial birds. To date, the OM team has conducted or participated in ten migration studies with three species. Operation Migration and USGS Patuxent Wildlife Research Center with assistance from the International Crane Foundation, the Wisconsin Department of Natural Recourses, The US Fish and Wildlife Service and other members of the Bird Team offer the following to the Whooping Crane Eastern Partnership (WCEP) as a protocol for costume-rearing, aircraft conditioning, translocation, flight conditioning, migration and subsequent release of Whooping cranes as required in Phase II of the reintroduction program. Extensive records will be kept on the treatment and response of the birds and the results will be evaluated so that this protocol may be revised as appropriate.
This protocol will guide activities for the initial release of Whooping cranes into eastern North America, however it is not feasible to use ultralight aircraft to introduce a flock large enough to be considered self-sustaining. It is expected that after enough birds have been shown a route south to establish a core group of migratory Whooping cranes, other methods will be employed to augment the population.
Whooping cranes introduced into an eastern habitat will not have the
benefit of wild conspecifics to teach them wild behaviour; 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 them
with proper sexual imprint models and raising them in small groups.
The birds we raise are neither tame nor wild. Like any creature
they have a natural fear of the unknown but the rest is a learned response
and our ability to teach them is severely limited. Just when to take to
the air to avoid a threat or how large a buffer zone is needed is learned
from the actions of the adult. Acting as surrogates, we are unable to
take-off immediately at the first sign of trouble or even to properly
convey the message that there is reason for concern.
If, while caring for the birds, we were approached by a curious
farmer or hunter we have no option but to accept the intrusion, where a
wild parent would fly off to a safer distance. The actions of the wild
bird teach its young to maintain a distance, while ours encourages
tolerance. Because we can only teach the bare minimum in human avoidance,
we need to rely on their natural fear of the unknown 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.
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.
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
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.
designed to disguise the human form, will be supplied by OM and used in
conjunction with hand held puppets of adult cranes and recordings of crane
calls. Sleeve cuffs or gloves
will cover the handler's hands when working with the cranes. When
necessary, the medical staff may remove their gloves and work barehanded
in order to properly treat or examine the chicks.
Absolutely NO TALKING will be tolerated within earshot of the birds.
* 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.
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 areas in order to provide a more natural environment.
number of handlers will be kept to a minimum during conditioning to reduce
the amount of human contact, improve handler safety and to minimize
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 agrees that
weather conditions, socialization and ages are appropriate. Heat lamps and
additional shelter may be provided as needed.
* The birds
will be socialized in small cohorts based on age and compatibility.
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 will be curtailed temporarily to limit
unnecessary human contact.
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.
aircraft used for this training are registered in Canada but are too large
to be considered ultralight's in the U.S. Through a cooperative agreement
between Transport Canada and the Federal Aviation Administration; we are
allowed to operate these aircraft within the U.S. providing we abide by
Canadian regulations. With
the wing removed to conduct this training they are not capable of flight
but still must be operated properly and only by qualified persons.
Bernhard Wessling has provided the project with digital crane call
vocalizers. Each unit is capable of reproducing 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.
As a precaution, the primary handlers will familiarize the cranes to the
sound of their human imitations of brood calls. This will be done
sparingly to afford some control over the birds in the event of equipment
failure in the field. Only the handlers that will accompany the birds
after they leave Patuxent should conduct this exercise and it should be
done from a distance so as to not attract the chick's attention to the
colts to follow aircraft:
Tape recordings of the aircraft engine sounds and recorded brood calls
will be played several times daily to pre-hatching eggs and newly hatched
When chicks are old enough to go outdoors, they will be introduced to the
real aircraft for the first time. The
wing will be removed, 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.
A small portable pen (ca 2-3 ft. in diameter and 2 ft. high) will be used
to provide the chicks with their next level of exposure to the aircraft.
This enclosure will be placed beside the trike 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.
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,
which 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 circle pen,
in which to temporarily place problem colts during training, will be
constructed in the center 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 and
times will be recorded on data forms.
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 pen to the adjacent field.
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
exposure to reinforce a positive response. During the advanced ground
training if weather permits, the chicks may be exposed to the aircraft
with the wing refitted to familiarize them to the final shape. The
duration of each exposure and the chicks' response to the aircraft will be
recorded on data 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. These containers will be modified to
prevent the birds from viewing un-costumed handlers through the
ventilation holes. The shipment will be conducted by private aircraft from
Suburban Airport in Laurel, Maryland to the Necedah Airport in Necedah,
Wisconsin to reduce the amount of ground travel needed.
The birds will be transported, in two air-conditioned vans from the
Necedah Airport to the Annex facility of the Necedah National Wildlife
Refuge. The vehicles will be parked in the shade and the birds will be
off-loaded, two at a time. A costumed technician will open the containers
and check the birds' eyes and mouths before they are hooded. The chicks
will then be moved into an adjoining room where the Medical Team will
conduct an examination of each bird. This will be performed without
talking and as quickly as is practical. Once completed the birds will be
returned to their containers and replaced in the vans. As soon as
possible, the birds will be released into the appropriate cohort pens and
monitored for signs of stress. The Medical Team will develop the protocol
for the examination.
Pens and Enclosures:
Two isolated pens and training areas exist at Necedah NWR and both will be
used to house the Whooping crane chicks. Site #1 will be modified to
accommodate a larger number of birds, giving us more options when it is
time to socialize the two cohorts. Additional trees will be planted in and
around the pens to enhance the natural look and the training area at Site
#1 will be widened and lengthened. Electric fencer units will be used to
protect both 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 will 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
* The birds will be released, as much as possible to forage on their own,
which will allow them time away from human contact and give them a chance
to establish their natural dominance structure. (It can be difficult to
return the birds to the holding pen in the evening.
The handlers will determine proper feeding levels to strike a
balance between providing adequate nourishment and controlled food
withholding so the birds will move into the pen on their own to gain
access to their feeders. This
method avoids unnecessary handling of the birds). Observations will be
made by remote monitoring from a blind or by video camera to determine the
* Once each group is able to follow the aircraft in the air as a cohesive
unit, the two cohorts will be introduced. This will likely occur at Site
#1 where the birds will be monitored for aggression, which will be
prevented if necessary.
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, barometric pressure, dew point, winds
and density altitude.
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
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. (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 start date
will be dependant on the weather.
* We will use the same route that was identified last year (2000) with
some modifications to the list of stopovers. Replacement areas have been
found for those that did not provide adequate isolation.
* A new travel pen and travel pen trailer will be constructed to
improve efficiency and bird safety. The improvements include a modified
shade shelter, which will allow the removal of some of the hard structure
within the pen. Additionally, an improved electric fencer system has been
designed. All changes will be presented for approval from the Animal Care
and Use Committee.
* 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.
Proposed Staging Area:
Due to impending cold weather of the central Wisconsin autumn, our
departure cannot be delayed too late in the season. However, as we head
south we are soon into warmer air that erodes the birds' flight endurance.
As well, our arrival in some of the southern states coincides with the
beginning of deer hunting season, meaning that hunters occupy many of the
areas we hope to use as landing sites. Most of the private landowners are
very willing to accommodate us, with the exception of the opening days of
the season. For these reasons, and also to provide a break for the
migration crew, we are proposing to stage the birds at a refuge along the
route for a period of one or two weeks. The Muscatatuck NWR, IN and
Hiwassee Wildlife Refuge, TN have been considered and appropriate areas
are available at both locations, however, the Tennessee site is farther
south and more suitable for our purposes. The Whooping Crane Recovery Team
will make the final decision. Under the guidance of the Refuge Manager, a
predator-safe holding pen will be constructed in an isolated area on the
refuge. The birds will be monitored and exercised daily by a minimal crew,
provided by ICF and/or Patuxent WRC in the absence of the field team.
Although the facilities will be in place, it is possible that the
migration will continue without a prolonged stop at the staging area. This
decision will be based on the progress to date, the weather forecast for
the remainder of the trip, the condition of the birds and other factors.
At this writing, a shortlist of appropriate release pen sites has been
identified at the Chassahowitzka NWR. The Refuge Manager will make the
final selection, with input from the selection committee.
Proposed Pen Design:
The following is a description of a release pen, similar to the ones
used in earlier studies. (Material list diagrams and photos available).
This structure measures 250 X 150 ft. and is not top-netted. It is
protected by three strands of electric fencer wire and erected entirely in
water 3 to 18 inches deep. The fencing material is eight ft. high -
plastic web fence (a natural colour would be preferable). One foot will be
bent out at the bottom and held in place with earth staples. It is
important that this pen be large enough so the birds can forage, unaware
that they are contained. Because of the electric fencer and the water,
ground predators cannot crawl under the barrier and are forced to jump
over it. The resulting "splash" as they land, acts as a warning
to the birds inside. A permanent shade shelter will be erected in the pen,
on evaluated ground, to provide a feed station.
* When the birds arrive they will be housed in their travel pen at an
isolated "last landfall site." During this time, the migration
crew will build a temporary holding pen in the center of the release pen
over the shade shelter and feeding station. It will be constructed of top
netting, using one of the door panels from the travel pen with which the
birds are familiar.
* Once this holding pen is complete, the birds will be led by aircraft to
the release pen area and encouraged to land next to the costumed handlers
that will be waiting for them. They will be kept in the holding pen at
night and released during the day to forage.
* The Medical Team will conduct the arrival examination at the release
pen. This procedure could be difficult to perform due to the isolation of
the area and a separate protocol will be established once the release site
has been identified.
* Several early morning flights will be made over the refuge to
familiarize the birds with their immediate surroundings.
* When appropriate, the temporary holding pen will be removed, leaving
only the release pen and the feeding station and the birds will be free to
fly. The birds will be led to another foraging location while the pen is
removed. They will be encouraged to stay in the area of the release pen by
means of a costumed dummy; regular visits by a costumed handler and an
ample food supply.
* A costumed handler will visit, twice daily for the first two
weeks and then, once each day for another two weeks. This will be reduced
to once every third day for a further week and thereafter the handler will
try to replace the feed only when the birds are elsewhere or by using an
automatic feeder. From this point on, observations should be made from a
blind, by video camera or by radio tracking. This release schedule is
discretionary and based on the flock behaviour.
* A supply of food will be made available at all times up to and past the
expected time of return migration.
* A video monitoring system will be used to observe bird behaviour.
Behaviour Options: We have several options to adjust the behaviour
of the birds, should they become sedentary or will not leave the area of
the release pen. These methods can be used to encourage the birds to seek
new foraging area or find fresh water.
* The aircraft could be used to lead the birds to other areas where
costumed handlers on the ground would encourage them to land.
* The crane recordings can be used to call the birds to other foraging
areas. In this scenario, a costumed handler would operate the loudspeaker
system in the early morning, when the sound would carry over a longer
distance. The handler would
spend several hours showing them how to forage for blue crab and other
foods. Later, the handler would return to the release pen to call the
* If the birds will only move out of the pen when accompanied by a handler
then we could consider removing the costumed dummy.
* Temporary or permanent food withholding could be considered.
Another option would be to remove the pen entirely.
procedures outlined above, combined with those from the WCRT and WCEP,
should afford maximum control over all aspects of an attempted
introduction of Whooping cranes.
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