Return of the Saker Falcon to Bulgaria

Return of the Saker Falcon to Bulgaria

A long-term conservation effort to restore the breeding population of the endangered Saker Falcon has reached an important milestone.

We can now report that for the first time in 20 years the Saker Falcon has been proved to breed in Bulgaria, with two chicks being raised. These pioneers were both bred in captivity and released as juveniles three years previously as part of a long-term reintroduction programme implemented by the Green Balkans Wildlife Rehabilitation and Breeding Centre (WRCBC) and the Environment Agency-Abu Dhabi (EAD).

The reintroduction programme has advanced in three stages:
• The first stage (2006-10), conducted in partnership with the Institute of Biodiversity and Ecosystem Research (IBER, Bulgarian Academy of Sciences), comprised (i) national surveys of former and potential breeding sites in Bulgaria and (ii) a feasibility assessment for reintroduction, including a population model to guide the release strategy.
• The second stage (2011-14), also undertaken in partnership with the IBER, involved a series of pilot releases of captive bred birds to (i) refine the release methodology, (ii) satellite track birds to determine movements and threats to their survival and (iii) the establishment of a captive breeding group to provide young birds for reintroduction.
• The third stage (2015-present) has involved the annual release of captive bred juveniles at a lowland hack site in order to establish the species in the agricultural landscape of Bulgaria.

This year, ornithologists from the Bulgarian Society for the Protection of Birds (BSPB) discovered an active nest of Saker Falcons in Bulgaria, the first proven case of breeding by the species in Bulgaria for 20 years. Suspecting that this event may have been the result of the reintroduction project, an ornithologist from the WRBC Green Balkans reintroduction team made the thrilling discovery that both of the breeding birds were indeed Sakers released as part of the conservation programme. Both were identified by their individually coded colour rings; they were hatched at the WRBC and were released in 2015, along with 17 other young Sakers, using a falconry release technique known as “hacking”. This was not the first time the female (ring code White 5P) had been sighted; she was known to have spent the winter of 2017/18 in Bulgaria . We are delighted to report that this pioneering Saker pair raised two chicks, the first youngsters known to have successfully fledged from a Bulgarian Saker Falcon nest in the wild this century.

Sakers typically start to breed when they are two or three years old, so the reintroduction team has hopes that further breeding pairs will be discovered in the coming years. The breed-and-release programme will continue, building on an international conservation collaboration between ornithologists and falconers, with the aim of establishing a self-sustaining breeding population in Bulgaria. The reintroduction project is directed by ecologists and the methodology is based on scientific evidence and utilizes falconry techniques for captive breeding and hacking. The captive breeding stock is of European origin, with the chicks reared by their parents in captivity until they are 25 days old, after which they are placed in a ‘false nest’ at the hacking site and fed with minimal human contact. The birds learn to fly and hunt independently but are encouraged to remain within the release area for at least one month after fledging through the provision of supplementary food, mimicking the natural behaviour of young Saker Falcons. Our satellite tracking studies revealed that this phase of the release process has an important influence of subsequent survival; birds that leave the release area prematurely have lower survival prospects.

Other Sakers from the release programme have been reported this year, including a two-year old bird that has been caught on camera returning to the hack site where it was released in 2016. Less fortunate was a youngster released in 2017, which was found poisoned near Sofia in June. The pilot tracking study identified a number of risks faced by young Sakers released in Bulgaria, and hence those that will be faced by a newly established population, the most important of which was electrocution at power lines, with young birds known to have been electrocuted in Bulgaria and Romania. In addition, two other young falcons have been caught by Libyan falcon trappers on autumn migration through North Africa. The reintroduction project has been able to identify these risks and also provide information on the movements and behaviour of young Saker Falcons fledging from sites in Bulgaria.
Background of reintroduction project

In the 19th Century the Saker Falcon had a continuous breeding distribution extending from Central Europe to the steppes of Central Asia; they formerly bred across much of the Balkans, including regions of Bulgaria, but habitat loss caused by changes in agricultural practices and industrialisation in the 20th Century reduced numbers and fragmented the population. By the late 20th Century the remnant Bulgarian population was finally driven to extinction by opportunistic thieves taking eggs and chicks for the illegal market in falconry species. Currently, the species distribution in the western part of its range is highly fragmented with a Central European population centred on the Pannonian Basin (mainly in Hungary and Slovakia), an East European population centred on Crimea, a low-density population in Turkey (from Central Anatolia to Northern Iran) and a larger, but declining, population east of the Caspian Sea in Kazakhstan. The diminished and fragmented western Saker population consequently has reduced genetic variability compared with larger, unfragmented Saker populations in the eastern part of the distribution range in Asia.

Surveys conducted in Bulgaria since 2006 revealed the presence of a small number of Sakers in the breeding season, but there was no proof of any breeding. The last proven breeding attempt was in 1998, when the nest was robbed of its young by falcon thieves. The aim of the Bulgarian reintroduction programme is to re-establish a breeding population in the southern Balkans in order to facilitate links between the existing population fragments in Central Europe, East Europe and Turkey. Reintroduction works by establishing a breeding nucleus comprising individuals bred in captivity and carefully released to the wild. Once they establish territories, these founders can potentially attract Sakers that pass through the region from other populations, especially those in Central and East Europe, to settle and breed. In this way, the Bulgarian population can grow and increase the likelihood of genetic interchange among the currently fragmented populations

This project forms part of a wider conservation effort to improve the conservation status of the Saker in the western part of its distribution range by restoring connectivity across population fragments from Central Europe to the steppes of Kazakhstan. The achievement of this long-term goal requires further efforts and collaboration between different institutions, communities and organisations in Bulgaria and internationally. The National Species Action Plan and the CMS Saker Falcon Global Action Plan provide a framework to facilitate this process.

The “Saker Falcon Reintroduction in Bulgaria” has been  implemented by Green Balkans and the Environment Agency – Abu Dhabi, with additional financial and logistic support  by Armeec Insurance JSC, Mohamed Bin Zayed Species Conservation Fund, ZOO BOJNICE, and Luboš and Marta Vaněk

Text by Andrew Dixon: