Reintroduction of Ural Owl (Strix uralensis) into the National park of Šumava

Reintroduction of Ural Owl(Strix uralensis)
into the National park of Šumava

The aim of this project is to return a rare species of large owl to the wilds of Šumava, this owl has
disappeared at the beginning of the century.
The birds that are reared in Ohrada ZOO and in other zoological gardens are let free into the wild.

Description of the project:

1. History of occurrence of Ural Owl in Šumava

The Ural Owl belongs to the original species of owls in Šumava. Certain differences in the habits led to a description of unique form of Strix schumavensia (Heyrovsky, 1851) in Šumava. At the turn of the 19th and 20th century Ural Owl appeared regularly on the Czech and the German side of Šumava and in its foothills. It was one of the westerly occurrences within the expansion area of Ural Owl in Western Palaearctic. He nested especially in mixed forests and the numbers reached there were several tens of nesting pairs. The main areas between Vimperk, Volary and Nova Pec were most frequented areas for Ural Owl. From the beginning of our century the number of Ural Owl started to decline, and the last information about nesting of this bird is available from the 20's and from the end of 30's Ural Owl is regarded as extinct on both sides of Šumava forest.

The reason for the great decline, respectively extinction of the Ural Owl from Šumava forest is difficult to define retrospectively. Available documentation shows that it was probably due to a combination of intense shooting with some other unfavourable conditions in the development of the environment (the reduction of mixed and leafy primeval forests, great fluctuation in the population due to possible climatic changes and gradation of small mammals, as well as genetic isolation of small population). Ural Owl is spectacular and tame owl, that is very often active during the day and near its nest, is very aggressive. It is possible to deduct, that then quite high population of Ural Owl in Šumava and the possibility to eliminate freely "vermin", had a distinct influence on the extinction of the Ural Owl, by being pursued by a man. At the moment the reintroduction of Ural Owl into the Šumava forests has perspective, because the threat of direct liquidation of Ural Owl is minimal. As a critically endangered species and therefore under legal protection, the possibility of illegal shooting thanks to generally favourable feeling towards birds of prey especially to owls, is fairly unlikely.

From the 30's to 70's a number of sightings of Ural Owl were recorded in Šumava. It is possibly a chance visit from a place of permanent expansion, distanced from Šumava several hundred kilometres away, but a possibility cannot be eliminated that it is a limited survival from the original population in Šumava. Occasional sightings of Ural Owl during the 80's and 90's on the Czech side of Šumava, can be due to reintroduction into the wild in the Bavarian National Park. The project to reintroduce Ural Owl on the Bavarian side of Šumava started at the beginning of the 70's and it is possible to say that at the moment this project is successful, as in the past few years several pairs of Ural Owl, that come from the released birds, have successfully nested in the wild. Anyhow, in the beginning, the project did not fulfil two of the basic conditions, the sufficient number of outgoing parental pairs (the basis for the breed comes from only nine specimens, an unwelcome inbreeding occurs when more than 200 young birds are produced). Their origin (majority of birds come from different zoological gardens and some belong to an unsuitable subspecies from Northern Europe). This German programme of reintroduction is now running in a limited form (annually only 8 young birds are released into wild). Up to now, not even on the Bavarian side of Šumava permanent numerate pairs can be found so that they would be able to reproduce and increase the population of Ural Owl. It is therefore very important to eliminate all the above unfavourable factors by marked strengthening of the genetically favourable population. It is possible to say, that the project to reintroduce Ural Owl into the Czech side of the Šumava should fulfil all these requirements.

At present in the Czech Republic the Ural Owl doesn't nest and apart from Šumava in the past centuries probably never nested. In Moravia during the 80's a small isolated nesting population formed in the region of Beskydy. It is possibly due to a gradual expansion of Ural Owl in the westerly direction from the Slovak Republic, where a numerate stabilised population exists. At the moment Ural Owl is found mainly in the mountainous forests of central Europe (Carpathian mountains and some regions of the old Jugoslavia and the Eastern parts of Alps). With all cases it is a central European subspecies of (Strix uralensis macroura WOLF, 1810) which is isolated from the main region of expansion of this kind in the extensive Palaearctic region of taiga.

Based on actual information regarding the feeding habits of Ural Owl; (larger part of his diet consists of small types of mammals, smaller number of birds, amphibians and insects. With today's knowledge regarding the population of small mammals, birds and even predators in Sumava it is possible to expect, that return of this larger predator into the biosensor of Sumava will not have great influence on the prey as well as on the feeding (also nesting) rivals. In considering the justification of reintroduction and the influence of Ural Owl we must not forget the reality, that Ural Owl belongs amongst predators, whose number and reproduction strategy depends greatly on the availability, or respectively on the surplus of food. Therefore the biggest pressure on the survival is in a period of gradation of smaller mammals. Concerning its trophic feeding strategy (wide feeding spectrum, hunting during night and day, winter roaming) with the present conditions in Šumava., there is no threat that Ural Owl would suffer from insufficient amount of food or that during reduction in the amount of food available he would compensate by its trophic specialisation.

2. Safeguarding the animals for reintroduction

The limiting factor to begin a successful reintroduction was to ensure a sufficient number of breeding materials. For the reintroduction from the genetical and economical point of view, it was best to use the Central European subspecies from Slovakia. The population of Ural Owl in this region is numerous and the removal of a certain number of individual birds can not in any way show an effect on the size and quality of the population. If you consider that there are about 500 pairs of birds in Slovakia and they produce minimally 500 fledglings in years that are not abundant with food, and in years with plentiful amount of food anything above 1500 fledglings, then the planned removal of 5 to 10 young per year represents an insignificant amount from the actual hatched numbers. The removal of the birds is carried out under strict rules; a fledgling can be removed only from a nest that has two or more young and is the smallest, these usually die for insufficient amount of food. Therefore, it can be said that the effect of removing the young birds, on the total number of young that have flown out is practically null and cannot influence in any way this population. Nesting and its success with the Eastern Slovak population of Ural Owl is supported by the provision and installation of nesting boxes, that are often used and the number of young reaches even higher number then with other methods of nesting.

The breeding methods of Ural Owl come from a number of published statements and from experiences obtained with breeding of Ural Owl in Bavarian National Park. To set up a group of breeding pairs it is necessary for the basis to use a combination of a larger number of individuals from the free population in different parts of Slovakia. The birds that have been brought from Slovakia, a sex-determination by endoscope method is carried out in the autumn and after that the pairing off takes place. These pairs are then placed in number of breeding facilities with adequate personnel and material base (Zoo Ohrada, in Hluboka nad Vltavou, Natural Science Organisation in Horazdovice, Organisation for Protection of Fauna in Pavlov, Zoo-park in Chomutov). The Ural Owl regularly nests here and brings out young, which are then let out into the wild or used to make up other sets of breeding pairs. From the experience we now have, it is possible to say that if feeding habits are good the breeding pair can bring out on average around two fledglings per year, and during their advancing years their number of young usually increases. It is possible to say, that with the planned permanent breeding system of 6 to 10 pairs of birds and other 5 to 10 young owls that will be brought over from Slovakia, that by the year 2005 we will let out into the wild of Sumava, between 150 to 200 specimens. This number together with the similar number of birds let out into the Bavarian National Park and in combination with the prepared reintroduction of Ural Owl into the Austrian part of Sumava, it is possible to say that it is the beginning of a strong population of breeding pairs in the region of Sumava.

3. Freeing into the wild

The actual freeing of Ural Owl into wild comes from tested method from the Bavarian National park. The bred pair is placed in special freeing equipment, which is taken to a favourable biotope area or to its proximity in Sumava. We are talking about a spacious aviary for parents and their young; these then are let out of the aviary during a favourable time usually towards the end of July. The young birds move within the vicinity of the aviary, this gives them visual, and vocal contact with their parents, this is very important during the adjustment period to the wild. During this time additional food is given to the young, but gradually they start to hunt their own food and within few weeks they leave the area of the aviary. Breeding pairs of birds with their young are placed into these specialised aviaries about one to two months before they are let free into the wild, longer or permanent nesting of the breeding pair showed to be too demanding on organisation and too costly. Sometimes young from the wild in Slovakia are added to the young from the permanent breeding pair. It is planned that in the future not only young birds but also their parents will be let free into the wild from these aviaries, which will enable a more natural development of the young with their parents and a longer time spent together after they flew out from their nest. A nesting pair that has been treated in this way is more likely to build up a nesting bond with the place where they have been released even in latter years (older birds usually do not move far from the place as do the young ones, these can move several tens of kilometres away during the first winter). It is assumed that it is possible to set up gradually more permanent nesting groups and a production of young birds in suitable areas by using this method. The number of freed nesting pairs will depend on the number of individual birds that will be suitable for this purpose. Ural Owl that have been bred by man, without long-term contact with their natural parents, are individuals with undesirable handicap after they have been released into the wild, they have the tendency to attack humans..

The freeing of Ural Owl takes place in areas where Ural Owl had appeared in the past with the National Park of Sumava. At present, there are three freeing facilities available, one near the village of České Žleby, other near Stozec and Rejstejn. The selection for the facility is placed preferably within a forest that is similar with its age and its composition to natural forest (in given conditions, mainly to mixed primeval forests with greater number of beech trees) in combination with open spaces which provides sufficient amount of food. It deals with areas where recent occurrence of Ural Owl has been noted and but these individuals do not come from this project. Due to the possible cross breeding between Ural Owl and Tawny Owl it is better where possible to prevent or restrain the contact between the two kinds of birds.

In the areas where the freeing takes places, suitable nesting boxes are installed, even though it is possible to expect that other nesting possibilities can be used such as (old nests from other birds of prey, in broken trees, on the ground etc.). All the freed birds have leg rings and microchips. Three specimens released in year 2000 have a transmitter implanted; with this aid, we shall be able to obtain important information regarding the movement of the birds after they were released into the wild for a period of up to one year. Overall, it is possible to state that the system of reintroduction is conceived with the maximum regard to the most natural breeding methods and the freeing of bred individuals to be carried out with the least amount of stress.

Due to the widespread dispersal of the freed birds, it is possible to expect a gradual but unpredictable expansion of the bird within the whole region of Šumava. It is unlikely that a long-term cumulating of individual birds will occur in the same area and even total density will not reach high numbers due to the extensive area of Šumava forest. At the same time the birds are being freed an evaluation is carried out to the changes in the number of Ural Owl in the selected areas. A check to the number of nesting boxes that are occupied and other potential nesting places are looked for, also an evaluation of the prey that is on offer and the composition of the diet of Ural Owl and any other activities.

From the beginning of this project in 1991, 31 young birds have been imported from Slovakia and 40 young birds have been bred in our zoological gardens. During the 1995 - 2000, forty-four young birds have been let free into the wild (as per table). With this, the first phase of this project has been successfully closed, the aim of this was to unite a team of workers, secure a good base for the realisation of the project, gather together genetically suitable individuals and start their reproduction. Confirm the breeding methods and the freeing of young birds into the wild. The whole project can be marked as successful even in this stage, because during the 1998 - 1999 after more than seventy years on the Czech side of Šumava it was again shown that Ural Owl is nesting freely in the wild. He nests near the areas where he has been set free and even in some other areas that are suitable for nesting have seen individual freed birds on a regular basis. Therefore it is possible to say that on the presumption that the reintroduction programme will continue, together with the consistent protection of Ural Owl in the wild, there is a real chance to increase the numbers and stabilise the nesting population of this owl in Šumava.

4. Acknowledgement

The project would not be able to run smoothly and successfully without the help from a number of organisations and individuals. The supply of the young fledglings of Ural Owl from Slovakia is thanks to the Forest department of the Technical University in Zvolen (Ing. Rudolf Kropil, CSc.), the Zoological Garden in Bojnice, Mgr. Štefan Danko, RNDr. Pavol Kaných, RNDr Štefan Pekla and MUDr. Ladislav Šimák. The help from departments of Protection of Nature of the Slovak Republic (mainly the Ministry of Environment for S.R.). A large part in the preparation and the commencement of work plays Ing. Jaroslav Červený CSc. It is also necessary to safeguard the breed, which up to now was the main responsibility of Zoological garden Ohrada in Hluboká nad Vltavou, they, from grater part also covered all their costs, (RNDr. Vladimír Holas, Petr Bednář, and other). Natural History Department in Horažďovice (Karel Průcha), Department for protection of Fauna in Pavlov, (RNDr. Aleš Toman with his co-workers), Zoo Park in Chomutov (MVDr. Martin Ptáček and others) other cooperation is taking place with Zoo Prague. The work and costs connected with the actual freeing of the bird into the wild is covered by the administration of the NP and CHKO Šumava (RNDr. Luděk Bufka, workers of LS from České Žleby, Stožec and Rejštejn) also very important is the work with NP Bavarian Forest (Dr. Wolfgang Scheizinger). The organisation of the whole project of reintroduction is managed by Administration of CHKO Třeboň (Ing. Bohuslav Kloubec). Part of the costs are covered by the Ministry of Environment for Czech Republic, Agency for the Protection of Nature and Environment in Czech Republic and Administration for Protection of the Countryside in Czech Republic.

Author of the contributions for our pages is ing. Bohuslav Kloubec from Administration of CHKO Třeboň.

PHOTOGRAPHS

1. Ural Owl in freeing aviary

2. All freed individuals have leg rings that have special microchips (fitting leg-rings)

3. Identification of Ural Owl with the aid of the microchip

4. Three birds that have been freed in year 2000 have such special transmitters fitted

5. Fixing of transmitter to tail feathers