The objectives of the new LIFE project includes the establishment of more Northern Bald Ibis’ colonies. The release of the young birds into the wild is an essential part of these colonies’ foundations.
Thanks to the European conservation breeding program for Northern Bald Ibises and the associated monitoring of the zoo populations, chicks with high genetic variability can be selected for release into the wild. As part of the new LIFE project, it is planned that there will be at least five hand rearing groups, each containing 30 individuals. The young birds are taken from the nests of captive colonies when they are two to eight days old, and hand reared by two foster parents. The first days of hand rearing take place in a zoo facility, where foster parents can be monitored by visitors. Ideally, the age difference between the chicks should be less than 10 days, so that the group is as uniform as possible during the training. During rearing, it is very important that the young birds only have contact with their foster parents to ensure a specific imprint. Yellow clothing and the familiar call “Come on Waldi! Come. Come!” will help the birds later identify their caregivers from afar. The rearing takes place according to a detailed plan, which incorporates 20 years of previous hand rearing experience.
Training CampJust before they fledge, at about five weeks of age, chicks and foster parents move to a mobile training camp near the colony site. When all the youngsters have fledged in their new homes, flight training begins. They need to learn to follow the motorized ultralight aircraft with a parachute, that will guide them to Tuscany in the late summer. To do this, they first get used to the machine, the engine noise, and the big parachute before they learn to associate their foster mothers with the aircraft. Only when they understand that the foster parents are flying as copilots do they reliably follow the aircraft. The training flights take place three to four times a week in an increasing radius around the camp. Towards the end, they are extended to two-hour flight times and short stopovers are also rehearsed. The training camps can be visited. Up-to-date information can be found on the website of the Waldrappteam.
Human Led Migration
Depending on the weather, the flight team of both humans and birds will head south around mid- August. Two aircrafts, each with a pilot and a foster parent, accompany the birds on their approximately 1000km long journey. The time of departure is determined by the onset of migratory unrest which can be determined by the weight, behavior, and hormone data of the birds.
An average daily leg during the migration is around 180 km with an average active flight speed of 45 km/h. In ideal conditions, the team even flies up to seven hours and 350 km a day. This distance is remarkable, especially compared to the first guided migrations, as 20 years ago it was no more than 30km a day! Today, the distance can be covered in five to seven days, with at least one rest day between the individual stages, so the human led migrations (HLM) last on average a little over two weeks.
In calm conditions, the young Northern Bald Ibises fly in an energy saving formation. If thermals set in however, they use the rising winds to circle up and glide to the next thermal bubble. It demands a lot of routine and experience from the pilots to maintain contact with the birds under the thermal conditions and guide them reliably. Alternating circling and soaring are the most efficient flight techniques for the birds and allows them to cover more distance without a break. Now, only one or two stopovers are necessary to refuel the planes.
For the HLM to run smoothly, a great deal of logistical effort is required. The team is accompanied in the air by several vehicles and trailers on the ground. For example, the mobile aviary in which the Northern Bald Ibises are housed between flights needs to be transported. Another vehicle transports the pre-portioned, frozen food for the birds. The team of around a dozen people usually camp at small airfields and are equipped with buses, tents, and a field kitchen.
To reduce the environmental impact of the project, the ground vehicles are to be converted to electromobility in the future. They will also be used in the first HLM of the new LIFE project 2022. For the time being, there is no realistic option for the aircraft to be electric.
ReleaseAfter arriving at the wintering area in Orbetello, the birds move to an aviary in the sanctuary to acclimate. Here, they are weaned from their foster mothers and are only cared for by regional employees with support from the WWF Oasi. Since some Northern Bald Ibises stay in the wintering area all year round, they also encounter other wild ibises. After a few weeks, the reintroduction can take place. The release that takes place is referred to as a “soft release” and it occurs in the presence of the foster parents. The birds are released in small groups of five to ten birds and are socialized with their wild counterparts. Until sexual maturity, usually at the beginning of their third year of life, most of the released birds remain in the wintering area and only sporadically migrate north.
Before they are released into Tuscany, each hand reared bird is given a GPS transmitter. The young birds in the breeding colonies are also equipped with such devices if possible. The transmitters are solar powered and sit on the bird’s back, at the base of their hind legs. A significant part of the Northern Bald Ibis population is now equipped with transmitters that provide comprehensive data on their spatial-time behavior. They enable basic research into bird migration and help clarify the causes of death.
The power of the transmitter depends on the intensity of the solar rays. Location storage and transmission intervals can be customized for each animal. The data is sent to a research database and visualized in a generally understandable way on the freely available app Animal Tracker. The movement of individual birds can thus be tracked almost in real time. No misuse of the data for illegal hunting activities has ever been detected. Publications of their whereabouts is considered to provide the birds with additional protection.
When birds are hand-reared, great care is usually taken to ensure that the young birds are not “human-imprinted”. In the case of the Northern Bald Ibis reintroduction, this is even forced: The nestlings are taken from the zoos before the parent imprinting is completed at about two weeks of age. In this way, the nestlings can be imprinted on their human parents, and this is the only way that the animals will follow them when they sit in the flying machines. And it is exclusively them, because it is not a general fixation on humans, but on exactly the two foster parents, which are recognized by the birds even after years.
The second important form of imprinting, sexual imprinting, on the other hand, takes place on their conspecifics. A Waldrapp raised in isolation with only human contact considers itself to be a human and does not bond with its own kind – it is actually misimprinted and unsuitable for breeding. In contrast, hand-reared birds raised in a group develop normally, show interest only in their own kind at breeding time, and raise their offspring without problems.