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Background research on the Swedish re-introduction of the Lesser White-fronted Goose

On request of the Swedish Nature Conservation Board and other authorities, a feasibility and background study was carried out for the Swedish re-introduction programme of the Lesser White-fronted Goose. 



Basic facts

Before World War II the Lesser White-fronted Goose (Anser Erythropus) was breeding in large parts of Northern Eurasia. Since then an alarming decline has occurred in its whole distribution range - in particular Scandinavia. The Swedish and Finnish natural populations were entirely lost in the 1980's and 1990's, respectively. Some fifty birds still survive in Norway.

The main reasons of decline seem to be deterioration of wintering grounds in in the Caspiaan Sea region, around theBlack Sea and in SE-Europe as well as hunting along the migration routes. Dr. Lambart von Essen started his re-introduction programme in Sweden in 1981. He decided to avoid the main threats by creating a new safe migration route. Therefore Semi-domesticized Barnacle Geese (Branta leucopsis) were used as foster parents for Lesser White-fronted goslings, who followed them learning to migrate to safe grounds in Western Europe.

By this well-working method a new nesting population of Swedish Lesser White-fronted Geese has been created. Today it consists of about 70-80 geese, all migrating to the Netherlands for winter.

The Swedish programme is following all IUCN Guidelines for re-introduction

The feasibility of the programme should be viewed against the background of the recommendations in the IUCN Guidelines for re-introductions, prepared by the IUCN Species Survival Commissions Re-introduction Specialist Group. We will do so at length below, citing the IUCN recommendations in italics.

Taxonomic status of individuals to be re-introduced:

(i) An assessment should be made of the taxomonic status of individuals to be re-introduced. They should preferably be of the same subspecies or race as those that were extirpated, unless adequate numbers are not available.

The Lesser White-fronted Goose has traditionally been regarded as a mono species with respect to both morphology, behaviour and habitat preference.

Recently some preliminary results have been published hinting at possible racial differences in mitochondrial DNA-markers of Lesser White-fronted Geese and hybridisation with other species. The relevance of these findings is unknown, as there is only limited access to genetic material from free living Lesser White-fronted Geese. A thorough investigation of the genetic - chromosome DNA - background of the captive stock in Sweden is being done during this year 2001. Controlling the Finnish stock at Hämeenkoski is planned but not as urgent, since they have a similar genetic history to the Swedish geese at Öster-Malma: According to von Essen virtually all Lesser White-fronted Geese available in European goose farms descend from West Siberian ancestors bought in Russia about one hudread years ago.

Regardless of the possible existence of genetically distinguishable populations of Lesser White-fronted Geese, the second requirement of the recommendation above is met in any case: adequate numbers of original Scandinavian stock are not available. In fact there are no wild Lesser White-fronts in Sweden or Finland at all, and the Norwegian population is also much too small to allow catching of birds without negative effects - a fact stressed by the Norwegian authorities, who object to removing any geese for breeding purposes.

It may as well turn out to be beneficial to import more variation into the genome of the Scandinavian Lesser White-fronted Goose population, since it is already so small. The dangers of incest are commonly known: diseases and low fertility. Taking all the above into account, the reasonable solution is to carry on with the re-introductions of the present captive stock from 2001 on when the results of the DNA - study will be public.

Potential migratory areas

(i) For migratory species, studies should include the potential migratory areas.

Migration routes and wintering areas of the Lesser White-fronted Goose have recently been thoroughly investigated by scientists and nature conservation authorities in the involved countries. Studies of the natural migration confirm our fears. To mention a few facts, wintering habitats are deteriorating in the important areas by the Caspian and Black Seas, hunting control has collapsed since the fall of the Soviet Union, spring hunting of waterfowl is still legal in Russia, poaching is common even inside nature reserves, and so on.

The contrary applies to West-European countries like the Netherlands: the populations of all wintering geese are increasing under controlled and safe conditions.

Optimal number and composition of individuals to be relesed

(i) The build-up of the released population should be modelled under various sets of conditions, in order to specify the optimal number and composition of individuals to be relesed per year and the number of years necessary to promote establishment of a viable population.

The Swedish assessment came to the conclusion that the number of released goslings, 20-30 per year, has been too small. For improved results more goslings should be released in the future. This is possible by the planned joint efforts of several European countries and institutions.

The re-introduction method:

(ii) Thorough research into previous re-introductions of the same or similar species and wide-ranging contacts with persons having relevant expertise should be conducted prior to and while developing the re-introduction protocol.

The current method of using Barnacle Geese as foster parents is already well established. well established and working. Only weakness of this method deals with imprinting phase of goslings. They are learing at first behaviour and habits of "wrong" goose species. During second year of their life they meet members of their own species and learn "right" behaviour and habits. This prolonged learning of "life style" corresponding Lesser White-fronts does not seem to interfere with later success of re-introduced geese. The Barnacle Goose is a stronger and more aggressive mother than the Lesser White-fronted Goose mother. This fact may benefit LWfG goslings during first migration journey and winter season.

A new technique developed and tested in the USA, Canada, France, and by the project in Sweden, namely imprinting goslings on an ultra-light aircraft and later using it to guide them over best possible routes to safe wintering grounds is available as well, but it is more costly to implement, and the current method seems to work well.

The choice and evaluation of the release site:

(iii) The site should be within the historic range of the species. ... For a re-introduction, there should be no remnant population to prevent disease spread, social disruption and introduction of alien genes. (iv) Re-introductions should only take place where the habitat and landscape requirements of the species are satisfied, and likely to be sustained for the foreseeable future.

The Swedish re-introductions satisfy these requirements; in particular they take place at a sufficient distance from the remnant natural population. Since the Lesser White-fronts choose their pairs in the wintering areas, genetic change with the remnant natural population is improbable.

The availability of suitable release stock:

(v) It is desirable that source animals come from wild populations. If there is a choice of wild populations to suply founder stock for translocations, the source population should ideally be closely related genetically to the original native stock and show similar ecological characteristics (morphology, physiology, behaviour, habitat preference) to the origininal sub-population. If captive or artificially propagated stock is to be used, it must be from a population, which has been soundly managed both demographically and genetically, according to the principles of contemporary conservation biology. Stock must meet all health regulations prescribed by the veterinary authorities of the recepient country and adequate provisions must be made for quarantine if necessary.

There are no wild Lesser White-fronted Geese available for re-stocking purposes. The captive geese have been soundly managed and they meet all veterinary requirements.

Release of captive stock:

(vi) A captive bred individual's probability of survival should approximate that of a wild counterpart.

In the Swedish re-introduction programme the survival probability of the released geese has been higher than that of wild counterparts.

Socio-economic and legal requirements:

(vi) Re-introductions are generally long-term projects that require the commitment of long-term financial and political support. Re-introduction must take place with the full permission and involvement of all relevant government agencies of the recipient or host country. This is particularly important in re-introductions inborder areas, or involving more than one state or when a re-introduced population can expand into other states, provinces or territories.

All these requirements are already fulfilled in the Swedish re-introduction project. The project is included in the International Action Plan compiled by the EU Life-Nature Fund and Wetlands International. This fact was recently confirmed at the meeting of the Lesser White-fronted Goose Task Force under Wetlands International in Belgium Jan. 7-8. 2000.

<> updated 9.jan.2001