Since 2004, the Waldrappteam has been guiding hand-raised juvenile Northern Bald Ibises with ultralight aircraft from the breeding colonies north of the Alps to the WWF sanctuary Laguna di Orbetello in southern Tuscany in order to release them there.
We have been able to optimise this method, which is currently only carried out by the Waldrappteam, over the last 20 years. The daily flight stages initially had a length of about 60 kilometres; in the meantime, we fly up to 300 kilometres a day. We have been able to triple the number of birds released per season up to 35 birds. The optimisations were mainly made in the areas of breeding process, adapting the flying equipment and research on the flying technique and flight efficiency of the Northern Bald Ibises. The expertise of professional pilot Walter Holzmüller, who has been participating in the migrations since 2007, has made a significant contribution to these adaptations.
Imprinting
The juveniles are collected from zoo colonies when they are only a few days old. So far, most of them have come from the colony at Rosegg Zoo in Carinthia (A), but various other zoos in Austria, Germany, Switzerland and the Czech Republic also provided birds for the program in the past.
Two human foster parents take care of the juveniles. Only the foster parents have contact with the birds and spend the whole day with them. This way, the birds are specifically imprinted on these two persons during the first two weeks of their life.
We practice what is known as socially involved hand-raising. This means that the foster parents interact directly and intensively with the birds. They do not wear masks or use dummies. Only a yellow overcoat enables the birds to recognise their foster parents from a greater distance during training later.
This parental imprinting leads to a social bond that is further stabilised and intensified by the constant presence of the two foster parents, daily care and intensive social interactions with each individual bird. This strong “social bond” forms the foundation for training, so that the birds later reliably follow their foster parents in flight legs up to hundreds of kilometres.
The exclusive contact with the two foster parents ensures that the birds do not develop a general affinity to humans after release. They can distinguish well between people and still recognise their foster parents from other humans years later.
Flight training
At the end of May, at the age of about six to seven weeks, the Northern Bald Ibises fledge. Flight training begins at the beginning of June. The camp is therefore always set up at the edge of a suitable take-off and landing runway.
Using the intensive bond with their foster parents, the juveniles are slowly habituated to the aircraft, the engine noise and the large parachute. In the beginning, the aircraft only drives on the ground, without a parachute. Only when the birds reliably follow the aircraft does the parachute come into play. The flights take place on mown meadows in an ever-increasing radius around the camp.
Training is carried out with only one aircraft. The two pilots, J Fritz and W Holzmüller, take turns and the two foster parents take turns flying as co-pilots as well. From mid-July onwards, extended training flights with distances of up to more than 70 kilometres take place. Only during the last flights towards the end of July is a second aircraft used for training. This way, both foster parents can join the training, which increases the birds’ motivation to follow them. In addition, the formation flight of both aircraft leads to a more stable flight behaviour of the birds.
Aircraft
Since 2007 we have been flying with two identical Xcitor aircraft from the manufacturer Fresh Breeze. This ultralight aircraft of the paraplane category is a two-seater with a powerful engine and therefore well suited for the project. The paraglider used is the Bigmax from Nova. It has a designed area of 60 m². This large size allows a maximum flying speed of 46 km/h, which is exactly in line with the flying speed of the Northern Bald Ibises.
In addition, the aircraft is equipped with an extra fuel tank, making flights of up to five hours duration possible. Another special feature is the fully netted propeller cage, which prevents the birds from touching the propellers during flight.
Migration
At the beginning of August, the Northern Bald Ibises become migratory restless and want leave the breeding areas. This means that the time has also come for the hand-raised juveniles to start their human-led migration.
The human-led migration starts in the training camp. The formations flies in daily stages of 100-300 kilometres, depending on weather conditions and geographical barriers. The active flying speed of the birds and the aircraft is around 40-45 km/h. Tailwinds can increase the cruising speed to over 100 km/h, but headwinds can also minimise the cruising speed or even make it impossible to move forward.
The flight formation consists of the two aircraft and the birds and is accompanied by a ground team, which usually comprises 8-10 people with different tasks. At least one vehicle accompanies the formation and maintains contact via radio transmitter. The remaining team dismantles the camp, including a 9*12 metre aviary, after take-off and then moves it to a new place where the flight formation has landed in the meantime. The camps are usually set up on small airfields.
A break day always follows the flight days. Depending on the weather, the stopover may take longer. During this time, the birds stay in the aviary and are intensively taken care of by their foster parents.
The flight distance of about 800 kilometres to the wintering area in Tuscany requires about 5-7 flight stages. In 2023, however, the migration will lead from Baden-Württemberg in the northern foothills of the Alps to a wintering area in Andalusia (ESP). This migration of more than 2,000 kilometres is almost three times as far as the previous flight distance to Tuscany.
The second wintering site is planned in the area of a sedentary Northern Bald Ibis population settled in Andalusia within the framework of the partner project Proyecto Eremita.
Release
After arrival in the wintering area, the juveniles are initially kept in an aviary for a few weeks. They are weaned from the intensive care of their foster parents and can get used to their new environment. Before release takes place, the juveniles are equipped with GPS transmitters. After release, the then free-flying birds quickly seek contact with their wild conspecifics and integrate into the local colony of overwintering birds.
Already in the following spring, the now subadult birds may undertake their first excursions northwards. Individual subadults can even fly as far as the breeding areas north of the Alps. At the latest when they reach sexual maturity at three years of age, most of the released birds return to their colony in spring for breeding The wild juveniles raised in these colonies then follow their conspecifics in autumn without further human intervention. This way, a new migratory tradition is created.
