ornithology

Endangered vulture returns to Bulgaria after being extinct for 36 years

Preliminary results from the releases of Cinereous Vultures (Aegypius monachus) were published in the Biodiversity Data Journal.

The Cinereous Vulture (Aegypius monachus) – also known as Black Vulture, Monk Vulture or Eurasian Black Vulture – is the largest bird of prey in Europe.

Globally classified as Near Threatened, its populations in southern Europe, once abundant, have been experiencing a dramatic decline since the late 1800s. So dramatic, in fact, that by the mid-1900s, these birds had already been nowhere to be seen throughout most of their distributional range across the Old Continent. In Bulgaria, the species has been considered locally extinct since 1985.

Thanks to the re-introduction initiative that was started in 2015 by three Bulgarian non-governmental organisations: the leading and oldest environmental protection NGO in Bulgaria: Green Balkans, the Fund for Wild Flora and Fauna and the Birds of Prey Protection Society, the species is now back in the country.

The project, aptly named “Vultures Back to LIFE“, where the Vulture Conservation Foundation (Switzerland), EuroNatur (Germany) and Junta de Extremadura (Spain) are also partners, has been co-financed by the LIFE+ financial instrument of the European Commission.

By mid-2022, the team imported a total of 72 individuals from Spain and European zoos, before releasing them in strategically-chosen sites in the Eastern Balkan Mountains and the Vrachanski Balkan Nature Park in Northwestern Bulgaria.

The team brought 63 immatures from Spain, where the birds had been found in distress and rehabilitated in aviaries. The other nine juveniles were captive-bred in zoos, and then released by means of hacking, which involves an artificial nest, from where the fledglings can gradually ‘’take off” to a life in the wild.

The re-introduction campaign to date is presented in a research article, published in the open-access Biodiversity Data Journal. There, the scientists led by Ivelin Ivanov (Green Balkans), report on and discuss the effectiveness and challenges of the different release methods and offer tips on the conservation and re-introduction.

For example, hacking proved to be inefficient for establishing an entirely new core (or nucleus) population of Cinereous Vultures in the Balkan Mountains in Bulgaria. It did not work for supplementing a small settled group of individuals either.

*A Cinereous Vulture on a hacking platform.*
*Photo by Hristo Peshev, Fund for Wild Flora and Fauna*.

Instead, the team recommend the aviary method and delayed release, where captive-bred birds are introduced to the new locality after a period of acclimatisation, where the birds can gain life experience to the local environment.

“The Cinereous Vulture re-introduction establishment phase in Bulgaria in the two first release sites is running according to the plan, and the first results are satisfactory,”
the scientists comment.

“Two distinct nuclei are now created, and the species started breeding, which might be a reason to up-list it in the Red Data Book of Bulgaria from ’Extinct’ to ‘Critically Endangered.’”

These two newly created breeding nuclei of the Cinereous Vulture in Bulgaria are the second and third of their kind in the Balkan Peninsula.

“Following a dramatic decline throughout the 20^th century for decades, the species had remained in only one breeding colony in Dadia-Lefkimi-Soufli Forest National Park in north-eastern Greece. Now, exchange between the three colonies will facilitate the exchange of individuals, ensure long-term stability, and give rise to the regional population,”
the authors of the study say.

However, the team points out that further monitoring and modelling and adaptive management are indispensable for the long-term persistence of the new national population. Now that there is already evidence that the imported vultures have been successfully breeding in Bulgaria, there is one step left before it can be officially confirmed that the Cinereous Vulture species has successfully re-established in the country. This conclusion can only be made after the core breeding populations begin to produce about ten chicks every year and after the locally fledged individuals begin to reproduce on their own. Such results are expected by 2030.

The re-introduction of the Cinereous Vulture is the latest in a series of conservation projects focused on birds of prey in Bulgaria.

First, in a programme that started in 2009, the Griffon Vulture was successfully re-introduced in Bulgaria after about 50 years of “extinction”. In fact, the team took a lot of the know-how and methods used in that project to apply in the present project. The success story was published in a research paper in the Biodiversity Data Journal in 2021.

The incredible return of Griffon Vulture to Bulgaria’s Eastern Balkan Mountains

In fact, the very same day in 2021 saw two publications in the Biodiversity Data Journal that reported on re-introduction successes involving birds of prey in Bulgaria, which had gone missing for decades. The second instance was the discovery of the first nesting Saker Falcons in twenty years

When conservation work pays off: After 20 years, the Saker Falcon breeds again in Bulgaria

Both scientific publications are part of a dynamic ‘living’ collection, titled “Restoration of species of conservation importance”, whose aim is to collate publicly available research studies reporting on the reintroduction and/or restocking of animal and plant species of conservation importance around the world. The collection was inspired by the “International Scientific Conference on Restoration of Conservation-Reliant Species and Habitats” held in Sofia, Bulgaria, in 2020.

“The restoration of species is one of the most important conservation tools in the context of constantly intensified human-driven global biodiversity loss. The reintroduction/restocking activities are related to significant research and data gathering before and during the work process, which ensures their sustainable success,”
explain the collection editors.

Research article:

Ivanov I, Stoynov E, Stoyanov G, Kmetova–Biro E, Andevski J, Peshev H, Marin S, Terraube J, Bonchev L, Stoev IP, Tavares J, Loercher F, Huyghe M, Nikolova Z, Vangelova N, Stanchev S, Mitrevichin E, Tilova E, Grozdanov A (2023) First results from the releases of Cinereous Vultures (Aegypius monachus) aiming at re-introducing the species in Bulgaria – the start of the establishment phase 2018–2022. Biodiversity Data Journal 11: e100521. https://doi.org/10.3897/BDJ.11.e100521

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Learning more about bird diversity: What a museum collection in Romania can tell us

“Due to its historical background and the presence of rare species, it is considered to be one of the most important ornithological collections in Eastern Europe,” researcher Gergely Osváth says

Containing specimens from different locations, sometimes spanning across centuries, museum collections can teach us a lot about how some animals are built and how we can protect them. Properly labeled, preserved specimens can show us how the environment and species distribution has changed over extended time periods. Because in many cases these collections remain largely unexplored, a revision can reveal “treasures” that were hidden in plain sight for decades.

The bird skin collection of the Zoological Museum of Babeș Bolyai University, Cluj-Napoca, Romania. Photos by Gergely Osváth and Zsolt Kovács

A team of ornithologists and scientists from the Zoological Museum of Babeș-Bolyai University, Milvus Group – Bird and Nature Protection Association and the Romanian Ornithological Society, headed by Gergely Osváth, set out to revise the ornithological collection in the Zoological Museum of Babeș-Bolyai University, Cluj-Napoca, Romania, checking the species identification of the bird skin specimens to provide an updated catalogue.

“The collection is unique in the region in many ways: it covers a long time span, it contains a variety of species, belonging to different families and orders, and it is composed of the work of several naturalists and employees of the museum”, Osváth says. “Due to its historical background and the presence of rare species, it is considered to be one of the most important ornithological collections in Eastern Europe.”

First, the researchers examined each bird skin and the data cards documenting the identification, locality, date, sex and catalogue number. Afterwards, they checked the species identification of specimens, determining the sex and age of birds where possible. They also updated the scientific names and taxonomy of birds. In addition, they provide a map representation with new distribution data for bird species, offering valuable information on the status of the avifauna of the Carpathian basin in the 19^th and 20^th centuries.

Published in the open-access journal ZooKeys, this is the first time that all those specimen data are made public.

The collection includes 925 specimens, belonging to 193 species, that were collected between 1859 and 2021. Perching birds (Passeriformes) were the best represented bird order, with 487 specimens, and 93.6 % of the specimens with known data were collected from Transylvania.

By far, the most interesting specimens were the rare ones, such as specimens of Cinereous Vulture (Aegypius monachus), Eastern Imperial Eagle (Aquila heliaca), Lesser Kestrel (Falco naumanni), all collected between 1903 and 1907 from Transylvania.

With updated information on the taxonomy and morphology of birds in Transylvania, the researchers hope this new catalogue can serve as a basis for valuable ornithological studies.

Research article:

Osváth G, Papp E, Benkő Z, Kovács Z (2022) The ornithological collection of the Zoological Museum of Babeș-Bolyai University, Cluj-Napoca, Romania – Part 1: the catalogue of bird skin specimens. ZooKeys 1102: 83-106. https://doi.org/10.3897/zookeys.1102.79102

The incredible return of Griffon Vulture to Bulgaria’s Eastern Balkan Mountains

Fifty years after presumably becoming extinct as a breeding species in Bulgaria, the Griffon Vulture, one of the largest birds of prey in Europe, is back in the Eastern Balkan Mountains. Since 2009, three local conservation NGOs – Green Balkans – Stara Zagora, the Fund for Wild Flora and Fauna and the Birds of Prey Protection Society, have been working on a long-term restoration programme to bring vultures back to their former breeding range in Bulgaria. The programme is supported by the Vulture Conservation Foundation, the Government of Extremadura, Spain, and EuroNatur. Its results have been described in the open-access, peer-reviewed Biodiversity Data Journal.

*Griffon Vultures in Eastern Balkan Mountains. Photo by Hristo Peshev, fwff.org*

Two large-scale projects funded by the EU’s LIFE tool, one of them ongoing, facilitate the import of captive-bred or recovered vultures from Spain, France and zoos and rehabilitation centres across Europe. Birds are then accommodated in special acclimatization aviaries, individually tagged and released into the wild from five release sites in Bulgaria. Using this method, a total of 153 Griffon Vultures were released between 2009 and 2020 from two adaptation aviaries in the Kotlenska Planina Special Protection Area and the Sinite Kamani Nature Park in the Eastern Balkan Mountains of Bulgaria.

After some 50 years of absence, the very first successful reproduction in the area was reported as early as 2016. Now, as of December 2020, the local population consists of more than 80 permanently present individuals, among them about 25 breeding pairs, and has already produced a total of 31-33 chicks successfully fledged into the wild.

*Vulture tagging. Photo by* *Hristo Peshev, fwff.org*

“Why vultures of all creatures? Because they were exterminated, yet provide an amazing service for people and healthy ecosystems”, Elena Kmetova-Biro, initial project manager for the Green Balkans NGO explains.

*Vulture tagging. Photo by* *Green Balkans, www.greenbalkans.org*

“We have lost about a third of the vultures set free in that site, mostly due to electrocution shortly after release. The birds predominantly forage on feeding sites, where the team provides dead domestic animals collected from local owners and slaughterhouses,” the researchers say.

“We, however, consider the establishment phase of the reintroduction of Griffon Vulture in this particular site as successfully completed. The population is still dependent on conservation measures (supplementary feeding, isolation of dangerous power lines and accidental poisoning prevention), but the area of the Eastern Balkan Mountains can currently be regarded as a one of the only seven existing general areas for the species in the mainland Balkan Peninsula and one of the five which serve as population source sites”.

*Vulture adaptation aviary. Photo by Green Balkans, www.greenbalkans.org*

Original source: Kmetova–Biro E, Stoynov E, Ivanov I, Peshev H, Marin S, Bonchev L, Stoev IP, Stoyanov G, Nikolova Z, Vangelova N, Parvanov D, Grozdanov A (2021) Re-introduction of Griffon Vulture (Gyps fulvus) in the Eastern Balkan Mountains, Bulgaria – completion of the establishment phase 2010-2020. Biodiversity Data Journal 9: e66363. https://doi.org/10.3897/BDJ.9.e66363

When conservation work pays off: After 20 years, the Saker Falcon breeds again in Bulgaria

The Saker Falcon (Falco cherrug) is a bird of prey living in plains and forest-steppes in the West and semi-desert montane plateaus and cliffs in the East. The majority of its Central and Eastern European population is migratory and spends winters in the Mediterranean, the Near East and East Africa. With its global population estimated at 6,100-14,900 breeding pairs, the species is considered endangered according to the IUCN Red List.

In Bulgaria, the Saker Falcon, considered extinct as a breeding species since the early 2000s, was recovered in 2018 with the discovery of the first active nest from its new history in Bulgaria. The nest is built by two birds that were reintroduced back in 2015 as part of the first ever Saker Falcon reintroduction programme. The results of the 5-year programme are described in detail in the open-access, peer-reviewed Biodiversity Data Journal.

Saker falcon, Bulgaria

Many factors contributed to the decline of the Saker Falcon in Bulgaria and globally, and most of them are human-caused. Populations lost big parts of their habitat due to changes in land use – the transition from grazing to arable crops led to the diminishing of key food sources. Other reasons include the use of poisonous baits and the accumulation of pesticides in the food chain, illegal trade of nest-poached chicks and eggs, power line electrocution, and lack of suitable nesting places.

Even after European legislation for the protection of wildlife was implemented, and regulations were issued on the use of pesticides in Bulgaria, the Saker Falcon population did not stabilise. Its endangered status further prompted joint conservation efforts between NGOs and national authorities.

As a result, a re-introduction programme for the Saker Falcon in Bulgaria was initiated in 2015, aiming to release a number of birds over a certain period of time using adaptation aviaries, or hacks. The Green Balkans Wildlife Rehabilitation and Breeding Centre (WRBC) in Stara Zagora facilitated the captive breeding of a group of Saker Falcons imported from Austria, Hungary, Germany, Slovakia and Poland by constructing ten breeding aviaries and two stock cages for juvenile falcons and equipping them with internal surveillance cameras.

Between 2015 and 2020, a total of 80 Saker Falcons – 27 females and 53 males, were released via the hacking method from four aviaries near the town of Stara Zagora. Out of them, 64 had been bred and hatched at the WRBC.

Observation records from 2018 confirmed that at least one pair of the falcons released in 2015 was currently breeding in the wild in Bulgaria. This observation proves that with the help of hacking, Sakers can survive in the wild until maturity, return to the region of their release and breed successfully. In 2020, the female bird in the breeding pair was changed with a Saker Falcon released in 2016, and the new pair bred successfully.

In 2020, the programme was restarted for another 5 years, with the aim to release 100 Saker Falcons and have six pairs breeding in the wild. This will help restore the Saker Falcon population in the southern Balkans and facilitate gene flow amongst fragmented populations from Central Europe to Kazakhstan.

Helping this iconic species successfully establish a self-sustaining population in Bulgaria has profound implications for conservation in the country – not only in terms of public awareness of species conservation, but also as an indicator of wider environmental issues.

Original source:

Lazarova I, Petrov R, Andonova Y, Klisurov I, Dixon A (2021) Re-introduction of the Saker Falcon (Falco cherrug) in Bulgaria – preliminary results from the ongoing establishment phase by 2020. Biodiversity Data Journal 9: e63729. https://doi.org/10.3897/BDJ.9.e63729

What is a species? British bird expert develops a math formula to solve the problem

Two different kinds of Lachrymose Mountain-Tanager (*Anisognathus lacrymosus*) occurring in Colombia on different mountain ranges (left: Santa Marta; right: Yariguies). Their measurements and songs were as distinct as those in the group which co-occur. Therefore, they can therefore be treated as different species.

Nature is replete with examples of identifiable populations known from different continents, mountain ranges, islands or lowland regions. While, traditionally, many of these have been treated as subspecies of widely-ranging species, recent studies relying on molecular biology have shown that many former “subspecies” have in fact been isolated for millions of years, which is long enough for them to have evolved into separate species.

Being a controversial matter in taxonomy – the science of classification – the ability to tell apart different species from subspecies across faunal groups is crucial. Given limited resources for conservation, relevant authorities tend only to be concerned for threatened species, with their efforts rarely extending to subspecies.

Figuring out whether co-habiting populations belong to the same species is only as tough as testing if they can interbreed or produce fertile offspring. However, whenever distinct populations are geographically separated, it is often that taxonomists struggle to determine whether they represent different species or merely subspecies of a more widely ranging species.

British bird expert Thomas Donegan has dedicated much of his life to studying birds in South America, primarily Colombia. To address this age-long issue of “what is a species?”, he applied a variety of statistical tests, based on data derived from bird specimens and sound recordings, to measure differences across over 3000 pairwise comparisons of different variables between populations.

Having analyzed the outcomes of these tests, he developed a new universal formula for determining what can be considered as a species. His study is published in the open-access journal ZooKeys.

Essentially, the equation works by measuring differences for multiple variables between two non-co-occurring populations, and then juxtaposing them to the same results for two related populations which do occur together and evidently belong to different “good” species. If the non-co-occurring pair’s differences exceed those of the good species pair, then the former can be ranked as species. If not, they are subspecies of the same species instead.

The formula builds on existing good taxonomic practices and borrows from optimal aspects of previously proposed mathematical models proposed for assessing species in particular groups, but brought together into a single coherent structure and formula that can be applied to any taxonomic group. It is, however, presented as a benchmark rather than a hard test, to be used together with other data, such as analyses of molecular data.

Thomas hopes that his mathematical formula for species rank assessments will help eliminate some of the subjectivity, regional bias and lumper-splitter conflicts which currently pervade the discipline of taxonomy.

“If this new approach is used, then it should introduce more objectivity to taxonomic science and ultimately mean that limited conservation resources are addressed towards threatened populations which are truly distinct and most deserving of our concern,” he says.

The problem with ranking populations that do not co-occur together was first identified back in 1904. Since then, most approaches to addressing such issues have been subjective or arbitrary or rely heavily upon expert opinion or historical momentum, rather than any objectively defensible or consistent framework.

For example, the American Herring Gull and the European Herring Gull are lumped by some current taxonomic committees into the same species (Herring Gull), or are split into two species by other committees dealing with different regions, simply because relevant experts at those committees have taken different views on the issue.

“For tropical faunas, there are thousands of distinctive populations currently treated as subspecies and which are broadly ignored in conservation activities,” explains Thomas. “Yet, some of these may be of conservation concern. This new framework should help us better to identify and prioritize those situations.”

Two different kinds of Three-striped Warblers (*Basileuterus tristriatus*) occurring in South America (left: East Andes of Colombia; right: a recently discovered population from the San Lucas mountains of Colombia). Note the differences in plumage coloration. While somewhat differing in voice, plumage and some measurements, the couple did not diverge as much as other related warblers that actually co-occur did. These are about as close as subspecies occurring on different mountain ranges could be. However, they marginally failed the proposed new benchmark for species rank.

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Original source:

Donegan TM (2018) What is a species? A new universal method to measure differentiation and assess the taxonomic rank of allopatric populations, using continuous variables. ZooKeys 757: 1-67. https://doi.org/10.3897/zookeys.757.10965

Additional information:

Donegan’s proposals were first presented orally at a joint meeting for members of the Neotropical Bird Club, British Ornithologists’ Club and Natural History Museum in London.

Feeding strategies in competing hummingbird species observed in a small area in Brazil

Being the vertebrates with the highest metabolic rate thanks to their rapid wing flaps, the hummingbirds have evolved various types of feeding behaviour. While the nectar-feeders tend to go for food high in energy, strong competition affects greatly their preferences and behaviour towards either dominance, subordination, a strategy known as trapline and a fourth one named hide-and-wait, conclude the Brazilian scientists Lucas L. Lanna, Cristiano S. de Azevedo, Ricardo M. Claudino, Reisla Oliveira and Yasmine Antonini of Universidade Federal de Ouro Preto. Their conclusions following six months of observations in an Atlantic Forest remnant in southeastern Brazil are published in the open access journal Zoologia.

To test previous assumptions as well as their own hypotheses, the researchers placed artificial bird feeders filled with variable in concentration sugar-water solutions across four separate patches at the core of the forest fragment.

The scientists sought to find out whether the birds would show clear preference for the most sugary food source; whether larger size and heavier weight would guarantee better access to the most nutritious feeders; what strategies would be adopted by each species; and which ones would prove the dominant and most aggressive.

As expected, the scientists concluded that the birds prefer the most sugar-dense solutions. However, when subordinate species, such as the white-throated hummingbird and the versicoloured emerald, confronted dominant species guarding the most nutritious food sources, they would be either frightened or expelled following a short chase. Subsequently, these hummingbirds would resort to the feeders with low-sugar solutions.

In their turn, the Brazilian ruby and the violet-capped woodnymph proved to be the dominant and most aggressive species in the studied area. Upon seeing an ‘intruder’ in their territory, which might be either another species, or belonging to their own, they would vocalise their threats, alert them by perching by the feeder, or expel them following a short pursuit. However, they would only try to limit the access for subordinate hummingbirds if the energy that could be gained from the feeder exceeded the energy loss of the chase.

Contrary to another initial hypothesis, it was not the largest and heaviest species that were the dominant ones. There were two species of hermit hummingbirds which were the largest and the heaviest, however, they expressed no territorial or aggressive behaviour. Instead, they were recorded intruding in the territory of the two dominant hummingbird species. In their turn, the Brazilian ruby and the violet-capped woodnymph would often frighten them. Nevertheless, rather than fleeing, the ‘castaways’ were seen hiding in the shrubs, remaining quiet, and returning to the feeder as soon as the dominant bird was gone. This behaviour strategy, named hide-and-wait, has not been reported in hermit hummingbirds prior to this study, according to the authors.

Having reported all feeding strategies in their study, the scientists conclude that the dominant territorial species and the trapliners feed most frequently and most sufficiently, as they use the most sugary sources.

However, the authors note that the high abundance of food, as well as the presence of aggressive territorial species might have affected the hummingbirds’ behaviour and preferences.

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Original source:

Lanna LL, de Azevedo CS, Claudino RM, Oliveira R, Antonini Y (2017) Feeding behavior by hummingbirds (Aves: Trochilidae) in artificial food patches in an Atlantic Forest remnant in southeastern Brazil. Zoologia 34: 1-9. https://doi.org/10.3897/zoologia.34.e13228

The owls beyond the Andes: Divergence between distant populations suggests new species

They might be looking quite identical, while perched above humanised farmlands and grasslands across several continents, but each of the populations of two owl species, living in the opposite hemispheres, might actually turn out to be yet another kind. This suggestion has been made by Dr. Nelson Colihueque and his team from Universidad de Los Lagos, Chile, based on new genetic divergence analyses of the Common Barn and the Short-eared Owl populations from southern Chile and comparing them with those from other geographic areas. The study is published in the open-access journal ZooKeys.

Although much has been known about the two widespread owl species, the knowledge about them has so far been restricted mainly to aspects such as their diet, conservation status and habitats. On the other hand, their genetic divergence in comparison with populations in distant areas has received little attention. Moreover, their taxonomical status is still based on traditional identification rather than modern methods such as the herein utilised mitochondrial COI sequencing.

Thus, the Chilean research team concluded a significant genetic divergence among the populations of both species from a few distinctive groups. In the case of the Common Barn Owl they compared the new analysis of its South American representatives with already available such data about populations from North America, Northern Europe and Australasia. For the Short-eared Owl, they compared Chilean and Argentinean birds with North American and North Asian.

One of the reasons behind such an evolutionary divergence might be the geographic isolation, experienced by the peripheral South American populations of both owl species. It is a consequence of the Andean Mountains acting as a natural barrier.

“In the case of the Common Barn Owl, the existence of geographic barriers to gene flow among populations on different continents is to be expected, and this in combination with its non-migratory or short-distance migratory behaviour, should contribute to promote the genetic divergence,” further explain the authors.

In conclusion, the researchers call for additional studies to clarify the taxonomic identification of these owl populations.

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Original source:

Colihueque N, Gantz A, Rau JR, Parraguez M (2015) Genetic divergence analysis of the Common Barn Owl Tyto alba (Scopoli, 1769) and the Short-eared Owl Asio flammeus (Pontoppidan, 1763) from southern Chile using COI sequence. ZooKeys 534: 135-146. doi: 10.3897/zookeys.534.5953