THE REINTRODUCTION OF THE BEARDED VULTURE, GYPAETUS BARBATUS (HABLIZL 1788) INTO THE ALPS *)

By Hans Frey and Maarten Bijieveld van Lexmond

Previous history

Stemmler (1932) started the discussion on the reintroduction of the Bearded Vulture into the Alps for the first time since the extermination of the species. His proposal to the Swiss National Park Comission as early as 1922 met however with resistance. Impressed by the breeding results of the Zoological Garden of Sophia (Schumann, 1928; Peters, 1935) Stemmler had already in those days the idea to use captive bred birds for this purpose. Also Heinroth (1927) discusses reintroduction and suggests the creation of feeding places as tourist attractions.

Following an unsuccessful attempt with wild cought birds from Afghanistan in France (Geroudet, 1979), Walter, WWF Austria, inspired by the remarkable and regular breeding successes of the Alpenzoo Innsbruck (Psenner, 1976; Thaler & Pechlaner, 1978), proposed an internationally coordinated reintoduction project, exclusively based on captive reproduction. FZG (Frankfurt Zoological Society) and WWF considered this application and agreed to finance the main aspects of the Bearded Vulture project (FZG 8?2/78; WWF 1567/78). At an international meeting in Merges, Switzerland, in 1978 the basic guidelines and modus operandi were elaborated (Bijieveld, 1979). Preperations for the first release of captive born young birds demanded a long period of time. The establishment of a sufficiently large captive population in numerous European zoological gardens alone required nearly ten years and is still continuing (Frey, 1988). Intensive public information as well as field research were equally important activities in this phase of the project. Yearly meeting and the Bearded Vulture Bulletin became important instruments of coordination.

Techniques of releasing

In 1986, it was decided to carry out a pilot study at the beginning of the releasing phase. Based on the results of the earlier field studies (Muller & Buchli, 1982) Rauris in the Hohen Tauern of Salzburg was selected as the first release site. As recent as the eighties lone Bearded Vultures of unknown origin had again and again shown up in this region (Hummel, 1982; Tratz, 1951; Tratz, 1963).

Due to the increase in captive reproduction, releases became also possible in the Haute Savoie, France, as from 1987, in Switzerland (Swiss National Park), as from 1991, and in the Maritime Alps, i. e. in the joint Regional/National Park of Argentera (Italy) and Mercantour (France), as from 1993. These release sites are situated at a distance of approx. 300 km from one another and cover the entire Alpine range. The fourth release site (Argentera-Mercantour) will also serve in creating a link with the nearby wild population of Corsica.

In line with the project's objective, i. e. the establishment of a breeding population totally independent of human management intervention, a release method was chosen close to the natural juvenile development of the Bearded Vulture: hacking back with the use of eyries (Frey, 1985). Nestlings are placed in imitation nests in small groups to guarantee social contact. This is done as soon as they are able to feed independently, i. e. at the age of about three months. Only young birds raised by parents or foster parents of the same species and brought into contact with each other while still being in the parental nest, are being used. Bearded Vultures breed as from the month of December. Consequently, they reach the right age at about the middle of May. At the release site a team of collaborators takes over the daily care and surveillance of the nestlings. Feeding is carried out avoiding direct contact by throwing food into the nesting niche. Guarding takes place from far-away observation point. Protocols are made of all events and activities in relation to the Bearded Vultures.

To ascertain an almost perfect superveying system, small radio-transmittors were fixed onto the backs of the Bearded Vultures during the pilot release of 1986 (d'Oleire-Oltmanns et al., 1989). The emitted signals were registered with mobile direction finders and two automatic receivers (Sonnblick, Schmittenhohe).

As from 1987 individual marking was obtained by bleaching particular wing and tail feathers.

The applied release technique knows two basic principles:

1. the imprinted attachement of the young birds to the release site and 2. the supposition that the elementary search for food is determined by instinctive behaviour, and that after the ending of ontogenesis nothing prevents the released Bearded Vulture reaching total independence.

In all, 50 Bearded Vultures were released since 1986. After eight years the outcome is the following:

Results:

1.Food independence

Young birds fly from their nest at the age of about four months. From this moment on, food is distributed near the nesting cliff and quickly consumed by the vultures. Already at the age of 4.5 - 5 months additional food from the wild is being taken, especially skeletons of sheep on the nearby alpine pastures. As from the early age of six months independence from artificially provided food resources is obtained, and, at least partly, they start to leave the release area. Consequently, artificial feeding is stopped in the month of August.

2. Philopatric Behaviour

As from 1986 releases have taken place in Rauris. Intensive contact occurs at times between birds of different age groups. Older Bearded Vultures accept, in most cases the presence of younger congeners, and let these accompany them on their extended flights returning all together to the nesting area. Apart from permanently present older Bearded Vultures, also other individuals who flegded from this site always returned at sporadic and long intervals. Thus, at certain moments, 9-10 different Bearded Vultures were observed in the valley of release in the summer months of 1990 and 1991.

3. Marking

Telemetry was abandoned in 1987. The results did not meet expectations, and especially the automatic receivers did not function in those cases whereby Bearded Vultures disappeared or found themselves at risk.

The individual marks, obtained by bleaching particular wing and tail feathers, can be well observed on flying birds over large distances, i. e. 2 km and over. They remain visible well into the second year, and sometimes up to the third year. After that, identification is only possible with the help of colour bandings. These however are only visible under very favourable circumstances. Particularly sedentary individuals can later on also be identified through moulting gaps.

4. Released birds found dead

Before being able to leave its nest in Haute Savoie a male died of disease in 1991.

The female "Melusine", released in 1987 in Haute Savoie, was found dead in a state of decomposition in Diemtigtal, Adelboden, Switzerland, on the 3rd July 1989. The findspot was situated in an avalanche gully at an altitude of 2000m. The stomach contents revealed the hoofs of a newly born chamois, while nearby the remains of some sheep were found. Thus, it could be concluded that death took place in May or early June. "Melusine" fell victim to an avalanche.

The male "Robespierre", released in Haute Savoie in 1989, collided with a high-tension wire and broke a wing. Subsequently, having been trampled upon by cattle, the bird died shortly after having been recuperated.

The fourth documented case of death concerned the female "Nina", released in Rauris in 1987. This bird settled in the Regional Pare of Ecrins, France, in 1988 and was shot there, possibly by a hunter, on 1st of August 1993.

5. Birds taken back into captivity

The female "Winnie", released as a late comer in 1986, was little active and not very independent as from the beginning. On the 18th of January 1987 it was found with its feathers frozen with ice, but otherwise unhurt, in the Molltal at a distance of 60km.

"Hubertus", a male released in Rauris in 1990, was unable to fly at an age of five months. It had also to be taken back into captivity.

"Republic 3", a male released in Haute Savoie in 1992, had to be recaptured in October 1992. Having been nursed back to good health after three months, this bird could be released again in January 1993.

6. Missing Bearded Vultures

The male "Saturnin" was released in Haute Savoie, France, in June of 1987. Having left the eyrie successfully it disappeared suddenly in mid-July. Since, observations of this animal have been lacking.

In Rauris, the male "Heinz", released in 1987, was regularly observed until September. From then on no indications as to his whereabouts exist. Contrary to "Saturnin", this bird was already independent and the time of its disappearance was not unusual. Also other Bearded Vultures left the release area at this age. But of these, however, certified observations from other Alpine regions do exist.

The male "Ulli", released in Rauris in 1988, paired there with the female "Paradatsch" in the summer of 1989, disappeared in the spring of 1992. Up to this date, both birds were found almost daily in the Krumltal, where they eveloped territorial behaviour.

7. Dismigration

The distribution of the remaining juvenile Bearded Vultures in the Alpine region is quite remarkable. They occupy preferentially the former strongholds of the species in the range of its distribution. However, the availability of food plays also an important role in the choice of a territory, such as Alpine meadows with sheep, epidemics among wild animals like chamois (scabies and blindness) and areas rich in avalanches and wild animals. Rich food sources do bind Bearded Vultures sometimes for months on end to a relatively small area, while in other cases reconnaisance flights of over 100km are carried out, which take up a few days and always end in an early return to the point of departure. In only exceptional cases lead such excursions to for Bearded Vultures untypical regions. This happend to the female "Baselisk" released in Rauris and observed in the coastal cliffs near Triest at the age of eight months. Young birds released from all the hitherto used release areas are in contact with each other thereby covering distances of over 600km.

8. Pair formation

In 1989 the first pair formation took place in the Hohe Tauern, Austria. The male "Ulli" and the female "Paradatsch", both released in Rauris in 1988, formed a pair in the summer of 1989, the male having taken the initiative. In the autumn the young pair began to show interest in an old Golden Eagle eyrie. They stayed together from 1990 until to the spring of 1992. Almost daily the pair was to be found in the Krumltal, where it developed a territorial behaviour and only tolerated juvenile congeners in the vicinity of the nesting cliff. In September 1991 the male took possession of a ravens nest and subsequently the pair constructed on top of this an impressive nest from branches and sheep wool. In the spring of 1992 the male "Ulli" disappeared and was replaced in the summer of 1992 by the female "Nicola", released in Rauris in 1991.

Pair formation took equally place in the Haute Savoie, France, where a pair was formed by "Assignat", released in 1989 and "Melchior", released in 1988. Both birds were released in this area. A second pair established itself in a distance of approx. 60km from the relase site.

In the Swiss release area pair formation, in all likelihood, also occured (A. Llopis-Dell & J. Schmidt, pers. comm.).

Another case of pair formation was be reported the Gran Paradise National Park, Italy, up to May 1993, when one of the two Bearded Vultures was violently attacked by a Golden Eagle. As a result of this attack, the vulture fell down in a wooded area and was never seen again.

9. Interspecific behaviour

Behaviour towards humans varies from being indifferent to showing curiosity. Tourists at roads are not at all looked at, while persons who find themselves at conspicious spots in the landscape draw the immediate attention of Bearded Vultures. They overfly them to inspect at sometimes very short distances, a kind of behaviour also known from "wild" Bearded Vultures. This for a birds of prey unusual lack of shyness has, up to now, only been for "Nina" a disadvantage as she was shot in France in 1993. With the exception of this case, there were no offences by hunters, proof of the acceptance and understanding on the biggest part of the hunting community in the countries concerned. The short flight distance, on the other hand, facilitates accurate observations, sketching and photography, which, in turn, allows for a fairly good documentation of the reoccupation of the Alps. Agressiviness against humans, which is often demonstrated by hand-reared, misimprinted Bearded Vultures, has never been observed.

Intentional disturbance or threatening of domestic grazing animals or wild ungulates, including direct attacks, were never observed. Alpine Marmots react to Bearded Vultures as they would to Golden Eagles or Griffon Vultures, i. e. they give the alarm call for aerial enemies being long drawn whistle. They, too, were never attacked by Bearded Vultures.

Interactions between Bearded Vultures and Golden Eagles show a great deal of variation. As larger predators are generally absent Golden Eagles have some importance in providing food. Normally Golden Eagles are extremely tolerant towards Bearded Vultures. Only rarely attacks occur, for instance, when they try to steal presumed prey from Bearded Vultures such as skins of Alpine Marmots. Such attacks, when sufficiently violent, may result in serious injuries of Bearded Vultures as it happened in the National Pare of Gran Paradise in May 1993 (P. & L. Fasce, pers. comm.). Vice versa Golden Eagles are successfully attacked and driven away by Bearded Vultures in the vicinity of their nesting cliff. Likewise juvenile Bearded Vultures are defended against Golden Eagles by older individuals. In winters with little snow and, therefore, few avalanches Bearded Vultures can be found in the close proximity of Golden Eagle families making use of the left-overs.

Conclusions

From field experiences with 50 Bearded Vultures during eight years the following conclusions can be drawn:

The release technique used came up to expectations and prognoses. The released Bearded Vultures distribute themselves over the whole Alpine range. Already at the age of six months they become independent of artificial feeding, and at this point in time the bone breaking behaviour starts to develop, i. e. the dropping and breaking of larger bones on stony ground. One of the goals of the project was thus reached, being the establishment of free living population independent of food provided by man.

Progress of this long term project has, so far, been encouraging. Losses were only slight in comparison to natural populations. This is probably explained by the fact that optimal biotopes are as yet not occupied by territorial breeding pairs. For that reason, it is difficult at his stage to make prognoses, of the future successful development of the overall project.

 
Summary

In the framework of the European Bearded Vulture Project (Frankfurt Zoological Society Nr.832/78 and WWF Nr. 1675/78), started in 1978, 50 young captive born Bearded Vultures were released by means of the "hacking" method as from 1986. Release took place in Rauris, Austria (21 birds) as from 1986, in the Haute Savoie, France (19 birds) as from 1987, in the Swiss National Park (7 birds) as from 1991, and in the National Park of Argentera-Mercantour, Italy-France (3 birds) as from 1993.4 birds were reported dead, and two birds had to be taken back into captivity. Young birds of all four release sites - maximum distance 600km - came into contact with each other. Up to now, pair formation has been observed in at least four cases. In two more instances there are strong indications that this equally happened. From 1991 on, nest building has also been observed.

References