Monthly Archives: Jul 2017

New bird that humans drove to extinction discovered in Azores

(SINC, Science Daily 26 July 2017; Credit: Pau Oliver)

Inside the crater of a volcano on Graciosa Island in the Azores archipelago, in the Atlantic Ocean, an international team of researchers has discovered the bones of a new extinct species of songbird, a bullfinch which they have named Pyrrhula crassa. The remains were found in a small cavity through which time ago the lava flowed. This bird disappeared a few hundreds of years ago due to human colonization of the islands and the introduction of invasive species.

Until hundreds of years ago, a species of bullfinch, a small songbird with a very short and robust beak, lived on Graciosa Island in the Azores archipelago. The arrival of humans to this island, however, depleted its population and it ended up going extinct, as was the case with numerous bird species on other islands, such as the Canaries and Madeira.

Now, an international team of scientists, backed by a project led by Josep Antoni Alcover, from the Mediterranean Institute for Advanced Studies (IMEDEA, CSIC-UIB), has discovered the bones of this bullfinch, called Pyrrhula crassa, in a cave located in a 12,000-year-old volcano in the southeast of the island.

“It is the first extinct passerine bird described in the archipelago, and it won’t be the last,” states Alcover, co-author of the study published in Zootaxa which focused on the analysis of beak morphology in order to determine the new species.

Despite there being few known remains of this bird, they are sufficiently distinctive for the scientists to have succeeded in establishing that they belong to a new extinct species of bullfinch.

The new bird, being the largest of its genus according to the size of the skull remains found, recalls due to its flying ability the existing bullfinch from the other Azores island (São Miguel) which is ‘vulnerable’ to extinction because of the expansion of agriculture and the disappearance of laurel forests.

“Its short and wide beak was not just considerably bigger, but also relatively higher than that of the common bullfinch or that from São Miguel, with a very robust configuration reminiscent to an extent of the beak of a small parrot,” asserts the researcher.

Invasions wiped out the birds

These islands were colonized during the 13th century by the Portuguese, although they could have been visited by Vikings over one thousand years ago. Just as has happened on many other islands, such as the Canaries or Madeira, different bird species have disappeared throughout the last millennium due to the arrival of humans along with various invasive species.

Human colonization led to the destruction and burning of the islands’ habitats in which humans started settling, and they impacted on the birds which were part of the indigenous fauna. P. crassa was no exception, finding itself affected until its extinction.

The introduction of invasive plant species has depleted and reduced the area of the laurel forests in which this species of bird lived by up to 3% of its original size. According to the scientists, although remains of P. crassa have only been identified in Graciosa so far, it possibly inhabited other islands of the Azores archipelago.

Grown-up gannets find favorite fishing grounds

(University of Exeter, Science Daily  27 July 2017)

Like humans, some birds can spend years learning and exploring before developing more settled habits.

A study of northern gannets has shown adults return to the same patch of sea over and over again to find food.

But younger gannets search far and wide and tend not to return to the same places — even if they find good hunting grounds, University of Exeter researchers found.

The study also compared successful breeding adults with those which failed to breed, and found successful breeders stuck to their feeding grounds more reliably.

“It’s common for birds like gannets to return to the same foraging grounds year after year,” said Dr Stephen Votier, of the Environment and Sustainability Institute on Exeter’s Penryn Campus in Cornwall.

“They disperse widely at sea, and the fact that they return to specific areas is presumably linked to finding good foraging conditions.

“However, gannets don’t breed until they’re four or five years old, and our research shows that this tendency to return to favoured foraging grounds is lacking in birds younger than this.

“This finding suggests that such behaviours are probably learned, and that gannets use their long period of immaturity finding good sites and remembering where they are.

“However, foraging sites in adults are not absolute — when experienced birds had more time on their hands after a failed breeding attempt, some became more exploratory. This suggests that refinement occurs throughout an animal’s lifetime.”

The research team studied gannets on the Welsh island of Grassholm, supported by the RSPB, and used precision global positioning system (GPS) loggers to find out whether individual birds returned to the same foraging grounds time after time.

Successful breeders showed strong attachment to certain areas and took similar routes when travelling to and from them.

Immature birds (aged two or three years) were much more varied both in foraging sites and routes taken.

The results support the “exploration-refinement foraging hypothesis” — that birds explore and slowly improve their foraging with age and experience.

New virus discovered in migratory bird in Rio Grande do Sul, Brazil

Calidris_fuscicollis2.jpg

(Fundação de Amparo à Pesquisa do Estado de São Paulo, Science Daily 25 July 2017)

Researchers at the University of São Paulo’s Biomedical Science Institute (ICB-USP) in Brazil have discovered a new virus in a migratory bird species. This is such a rare find that it can be considered a stroke of luck, especially because the virus in question is avian paramyxovirus 15, which belongs to the same family as avian paramyxovirus 1, the pathogen that causes Newcastle disease. This disease is not a health hazard for humans but can be lethal to wildfowl and domestic poultry.

“We perform active monitoring of viruses in migratory birds. I was looking for Newcastle disease virus, a type 1 avian paramyxovirus, and my colleague Jansen de Araújo aimed to detect avian influenza virus for his research project. Finally, we found a co-infection by two viruses, one of which was totally unknown until then,” said Luciano Matsumiya Thomazelli, a researcher at ICB-USP’s Clinical & Molecular Virology Laboratory.

Since 2005, the lab team has been going into the field to perform epidemiological surveillance in different parts of Brazil as part of the Viral Genetic Diversity Network (VGDN), funded by FAPESP and headed by Professor Edison Luiz Durigon.

Their goal is to detect the presence of avian influenza virus and Newcastle disease virus, among others, in birds and other wild animals. In addition to monitoring, they aim to assess the risk of new strains arriving in Brazil. The samples collected by the team are stored in freezers at -80 °C and used in scientific research.

The new virus was found in a sample taken from a white-rumped sandpiper (Calidris fuscicollis) captured in April 2012 in the Lagoa do Peixe National Park in Rio Grande do Sul State. More research is required to determine how much of a threat the virus represents, but, the current evidence suggests that it is not a risk to humans. “Genetically speaking, it’s closer to viruses first described in South America, which leads us to believe it may have originated in this part of the world,” Thomazelli said.

The researchers followed the standard method for analyzing samples. The result was positive for avian influenza on the basis of real-time PCR, a molecular biology technique that detects DNA or RNA in the sample. When the virus was isolated from embryonated chicken eggs, the result was negative for Newcastle disease virus, but the red blood cell agglutination reaction showed that it was a different virus from the one that the researchers were seeking.

“We sent the sample to collaborators at St. Jude Children’s Research Hospital in Memphis, Tennessee (USA), who sequenced the complete genome of the large amount found in the sample. To our surprise, the sample contained a co-infection by avian influenza virus and something entirely new. We focused on influenza and found this other virus as well,” Thomazelli said.

On the basis of these results, the researchers performed biological tests for pathogenicity and data confirmation. Because biosafety was involved, they sent an aliquot of the isolated virus to the Agriculture Ministry’s National Laboratory, which also performed biological and serological tests confirming that the virus was a new species and did not pose a threat.

“This was a relief, especially considering that Brazil is the world’s leading exporter of frozen chicken,” Thomazelli said. “Any pathogenic avian virus would be a major concern, especially if it affected poultry, but that’s not the case.”

The discovery of new viruses is still a rarity, but it is becoming less infrequent because of next-generation sequencing.

“The virus we discovered is the 15th type of avian paramyxovirus. Two years ago, there were only ten types. Knowledge in this area has increased significantly as a result,” Thomazelli said.

Fifty years on, the Breeding Bird Survey continues to produce new insights

(Science Daily, American Ornithological Society 26 July 2017)

In 1966, a U.S. Fish and Wildlife Service biologist named Chan Robbins launched an international program designed to measure changes in bird populations using volunteers recruited to count birds on pre-set routes along country roads. The result, the North American Breeding Bird Survey or BBS, is still going strong more than five decades later. This month The Condor: Ornithological Applications is publishing a special set of research papers to honor the program’s fiftieth anniversary.

Unassuming but visionary, Robbins had studied DDT’s effects on birds — his reports were edited by Rachel Carson — and he wanted to devise a way of monitoring the health of the continent’s bird populations on a large scale. The simple field protocols he developed, able to be carried out by volunteer birdwatchers, have remained largely the same since the program’s inception. Today, there are more than 4100 survey routes spanning North America from Alaska to Newfoundland, Florida, and northern Mexico.

The BBS provides long-term data for 424 species, with more limited data for an additional 122. Since data collection began in the 1960s, significantly more species have been declining than increasing. Looking at patterns of change in groups of birds sharing common attributes can be especially useful; for example, only 8 of 24 grassland bird species have seen increases. However, in the short term the picture is slightly rosier — since the survey area was expanded in 1993, 56% of the species surveyed have showed positive trends. Today, modern statistical techniques are letting ornithologists glean more insight from BBS data than ever before.

“The BBS is the only source of long-term, multi-scale population change information for more than 500 species of North American birds,” according to the USGS’s John Sauer, who has worked with the BBS since 1986 and was one of the co-editors for the special section along with Keith Pardieck and Colleen Handel, also with the USGS. “BBS results have allowed conservationists to identify bird species and regions undergoing population declines, alerting the public and scientists to population changes and facilitating the development of initiatives to better understand declines.”

The papers that make up the special section in The Condor include:

  • Prioritizing areas for conservation by combining six years of BBS data with remotely sensed environmental data to model the predicted distribution of seven grassland bird species in the Northern Great Plains based on their habitat needs.
  • Statistical approaches for model selection in BBS analyses.
  • Combining BBS with off-road surveys to estimate population changes for birds that breed in Alaska, where habitats are being rapidly altered due to climate change.
  • Using long-term BBS data to rank the vulnerability of more than 460 landbird species, set population objectives, and track progress toward meeting conservation goals.
  • Analyzing how well road-based BBS routes represent larger landscapes, using data from 2011 National Land Cover Database, with the conclusion that any land-cover-based roadside bias in BBS data is likely minimal.
  • Combining BBS data with separate demographic data to estimate the size of the Atlantic Flyway’s Wood Duck population.
  • Plus, a review of how the BBS has informed North American bird conservation since its inception.

The papers grew out of a research symposium held at last summer’s North American Ornithological Conference in Washington, DC, to commemorate 50 years of the BBS. “The BBS provides a fundamental tool for understanding breeding bird distribution and abundance. We’re pleased to publish these papers that celebrate Chan Robbins’s vision and the hard work of thousands of volunteers through the latest results and analyses,” said Philip Stouffer, Editor-in-Chief of The Condor: Ornithological Applications.

The common cuckoo is an effective indicator of high bird species richness in Asia and Europe

Cuculus canorus2.jpg
(Federico Morelli, Anders Pape Møller, Emma Nelson, Yanina Benedetti, Wei Liang, Petra Šímová, Marco Moretti, Piotr Tryjanowski 29 June 2017)

Introduction

Why is the common cuckoo Cuculus canorus a fascinating bird species for humans? What are the main reasons for the species being known as “a messenger of spring and morality”1, and why is it so conspicuous in human culture? A review of folklore shows clearly that the enigmatic cuckoo has driven the collective imagination of people throughout the world for thousands of years. First and foremost the cuckoo-call is associated with seasonal change. The timing of arrival of the cuckoo and the vigour of its calls were also used as indicators of the weather2, 3. In ancient Egypt, Aristophanes wrote that its arrival was associated with harvest time2. Cuckoo lore is intimately linked with change and metamorphosis1,2,3 and its call reflects the real world passing of time when seeds are transformed into crops, maidens are married and maids become mothers.

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Results

A total of 65,234 observations of bird occurrence in 3,592 sample sites in different environments were collected from ten European and two Asian countries. The maximum bird species richness per point count in all countries ranged from 12 species (Finland), to 28 species (San Marino and Switzerland).

_________

Sample sites were treated as statistically independent observations because the spatial autocorrelation in all studied countries was not significant

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The temporal trend in common cuckoo populations was positively correlated with the overall trend in bird populations in European countries

__________

Discussion

Cuckoo as indicator: Extending species surrogacy from Europe to Asia

This study provides new evidence on the common cuckoo as a surrogate of bird species richness, previously tested in some European countries. This suggests that the common cuckoo is potentially a prime bioindicator in Eurasia. Even if related to different host species, and considering that the common cuckoo is not the only parasitic cuckoo in Asia24, we found the same pattern than in Europe: Occurrence of the common cuckoo is positively correlated with bird species richness in both continents. The implications related to finding the same pattern in Europe and in Asia are important from an ecological point of view. First, in Asia, C. canorus has different host species than in Europe. Second, the common cuckoo is not the only brood parasite in China and Japan. So, C. canorus is subject to a greater competitive pressure from other cuckoo species in Asia than in Europe. However, common cuckoo still shows the same capacity as surrogate of bird species richness, highlighting the process linking this particular (and charismatic species) to overall bird diversity.

___________

Our study shows that the population trend of common cuckoo, as well as climate suitability trend for the common cuckoo, follow the overall trend for populations of all other passerines species and the climate suitability trend in all Europena countries. This result supports the hypothesis that common cuckoo is a suitable bioindicator, making the species also sensible to climate change scenarios. When using proxies of population trends, many aspects need to be considered. For instance if within country variation in population abundance trends of different species is larger or smaller than variation among countries, and also how trends of other bird species can be related to the average community trend.

Read whole study

 

Caribbean Lowland Birding at Ara Ambigua Lodge, Costa Rica

 

(Patrick O’Donnell 22 July 2017)

As with peninsulas and places situated on an isthmus, Costa Rica has more than one coast. In the west, the Pacific splashes against beaches, estuaries, and occasional rocky spots backed by dry forest that transitions into rainforest as we head to the south. Over on the other side of the mountains, the rivers and streams rush their way down slope to eventually get muddy and meander their way to the Atlantic. Since that part of the Atlantic belongs to the Caribbean Sea, locally, the eastern low elevations of Costa Rica are also referred to as the “Caribbean lowlands”. However, other than some communities made up of people of Jamaican heritage, there’s actually not much Caribbean about it. White-crowned Pigeon might be on the list, but that rare prize for Costa Rica is far from regular. Birds with white on them are much more likely to take the form of goodies like the Snowy Cotinga, or two species of tityras. In Costa Rica, even the super shy Slaty-backed Forest-Falcon is seen more often than the island pigeon with the snow-white cap.

Masked Tityra– the most frequently encountered small bird in Costa Rica with white plumage.

The Caribbean slope of Costa Rica also differs from the islands in having a lot more bird species. The lowland forests of this region are actually the most avian-rich part of the country and host around 400 some species. Although a lot of beautiful rainforest was replaced by bananas, cattle pasture, and other ag-lands many years ago, at least we can still enjoy great birding at a number of sites, most of which are easily accessible including Sarapiqui, the most visited site in the lowlands north of San Jose. This is where we find the La Selva Biological Station, Selva Verde, Tirimbina Reserve, and several options for lodging. Given the ease of access (except La Selva, a site only accessible by paying a fair bit to stay there or take a guided walk), it’s kind of odd that the Birding Club of Costa Rica doesn’t visit more often. To make up for our collective absence, we did a trip there last weekend. As with most of the club excursions, I was the guide and the weekend involved a mix of tropical birds, good food, and good company at a local lodge that treated us well. On this occasion, the accommodation in question was Ara Ambigua Lodge, and after staying there, I am happy to say that it acts as a good base for this bird-rich zone.

Owned and run by a local family, they treated us very well, even making sure that we had coffee by 4:30 in the morning. The food was healthy, substantial, and delicious, rooms were comfortable and air conditioned, the hotel strives to be as sustainable as possible, paths between the many rooms were well lit, there are frog ponds with Red-eyed Tree-Frogs and other species just outside the restaurant, and the hotel is a quick drive to La Selva, Dave and Dave’s Nature Pavilion, and around a two hours drive from the San Jose area. I recommend staying there but what about the birds?

Although the hotel isn’t situated in an extensive area of forest (very few places in Costa Rica are), it nevertheless works well for good edge and garden birding and the patch of rainforest behind the hotel could hold some surprises.

Read more

Molting feathers may help birds deal with environmental contaminants

Preview image
(Wiley 20 July 2017)

Mercury is a ubiquitous environmental contaminant that affects the health of birds and other wild animals. Two varieties of songbird—zebra finch and European starling—were found to shed mercury accumulation with their feathers in a recent study.

During a molt, both species quickly eliminated mercury from their blood and significantly reduced mercury concentrations in other tissues. This, coupled with a migration out of contaminated sites, may help birds deal with exposure to environmental toxins.

“It came as no surprise that feather molt accelerated the mercury elimination, but we did not expect the rates to differ so markedly from the non-songbird species that have been studied previously. Understanding species differences as well as how molt contributes to mercury elimination can improve risk assessments,” said Margaret Whitney, co-author of the Environmental Toxicology & Chemistry study.

Birds avoid crossing roads to prevent predation

(Science Daily 19 July 2017)

Roads can be dangerous to wildlife. Animals making the perilous journey against the traffic run the risk of meeting an untimely death. Until recently, it was widely believed, unlike other animals, birds were largely unaffected by the presence of roads and traffic, simply because they could fly.

A new study, published in the open-access journal, Frontiers in Ecology and Evolution, reveals this is not the case. Birds can find roads challenging too – they are less likely to be found next to roads and are hesitant to cross them.

“We observed fewer bird species and individuals of each species near to roads. In addition, they were less likely to cross wide roads,” says Christopher Johnson, who completed this research as part of his graduate studies at the Griffith University, Brisbane, Australia. “We found the smaller-bodied, forest-dependent species were the most affected, avoiding all but the narrowest of roads.

A keen bird-watcher, Mr. Johnson spent many hours carefully recording birds seen next to and crossing roads of different widths around the southern suburbs of Brisbane, Australia. He made sure that the vegetation on either side of the road of his recording sites were the same, as it was more likely that bird crossings occurred between similar habitats. These results were compared to the number of birds seen and heard in the vegetation 100m in from the roadside, to see if the species and numbers of individuals differed.

“For this study, we decided to try something new, by looking at the influence of different road widths (two, four and six-lanes) on bird crossings. In addition, we analyzed the road-crossing ability of birds of different body sizes and whether the type of bird, for example, small forest dependent, large forest dependent, honeyeater or urban tolerant species, had an effect,” explains Mr. Johnson.

The results were quite clear. The widest roads – six-lane carriageways – had fewer bird species and individuals of each species crossing them than the narrower two- and four-lane carriageways. When they looked at the different body sizes and bird types, it was the smaller forest-dependent species that showed the biggest difference.

The authors have suggested several reasons for these findings, such as birds choosing not to come out into the open for fear of predation and the creation of territorial boundaries, as breaks in vegetation can be used by birds to mark the edge of their territory. In addition, many highly aggressive, territorial bird species were seen to be taking advantage of the space near the roads, which would put off other birds crossing.

The findings of this study raises concerns, because bird species play an important role in the health of our natural environment.

Professor Darryl Jones, co-author of the study and Deputy Director of Environmental Futures Research Institute and the School of Environment at the Griffith University explains. “Birds perform a range of services that are of huge benefit to humans, from controlling pests such as mosquitoes and flies to the pollination and seed dispersal of many plants, including those of economic and medicinal value. By restricting bird movements through transportation networks, we are limiting their ability to perform these services and, ultimately, undermining the benefits we gain.”

The authors of the study strongly advise that measures are put in place to connect fragments of forest across roads, allowing wildlife to move freely.

“People use the road transport system to get from point a to b. Unfortunately, this has a negative impact on wildlife movement, particularly within urban environments,” says Daryl Evans, who also collaborated on this the research and is based at the Griffith University. “There are wildlife-friendly solutions to many of these issues, such as specially-designed overpasses, fauna underpasses and fencing so animals can avoid accessing the road, all of which need to be incorporated into the design of our road systems.”

“Further studies should look at the impacts of man-made breaks in vegetation, such as forest tracks and park walkways on bird movements,” adds Professor Jones. “We are currently using our data to identify the ‘at risk’ bird species within suburban areas, to assist with conservation management.”

These birds are trapped between predators and rising sea levels

seaside sparrow fledglings Mary Beth Griggs July 12, 2017

Probing its beak into the soft mud, looking for seeds or insects, the Seaside Sparrow is a common sight on the southeastern coasts of the United States.

Biologist Elizabeth Hunter started studying the small birds as a part of her dissertation at the University of Georgia. She wanted to know how sea level rise—which is already happening in Georgia at a rate of 3 mm/year—would threaten the sparrows. Then, she noticed something surprising.

“Over three years of collecting field data on Seaside Sparrow nesting success, I noticed that many more nests were being eaten by predators than being flooded by high tides,” Hunter said in an e-mail to Popular Science.

Not wanting to overlook an important threat to the population, Hunter, now at the University of Nevada, Reno, decided to create a mathematical model that would take both predation and sea-level rise into account. She found that while flooded nests were a threat to Seaside Sparrows, they were far more likely to build their nests lower in shrubs where predators were less likely to reach them, even if that meant their nest might get flooded more often.

Hunter says that sea level rise has made the risk of Seaside Sparrow nests flooding five to ten times more likely now than in the 1980’s. When a nest floods while empty, or when a few eggs are tucked inside, the flooding is generally manageable. So long as the eggs don’t float away, the sparrows can rebuild.

“The danger is when the nest has nestlings. Nestlings stay in the nest for 10 days after they hatch until they fledge, and if the nests floods while they are still in it, they can drown,” Hunter said. “Adults themselves aren’t really affected by flooding, but they do have to expend more effort to make a new nest and care for eggs and hatchlings if a nest is lost.”

In addition to the threat of the rising sea, the sparrows face assaults from the sky and the land. Fish crows, grackles, red-winged blackbirds, and marsh wrens attack from above, while raccoons, mink, and marsh rice rats mount a ground assault.

During seasons when predator activity was high, the sparrows kept their nests low to the ground. When they lost a nest due to flooding, they built higher, but the predator pressure weighed heavier in their choices than the flooding experience. Caught between gnashing teeth and the deep blue sea, Hunter estimates that predators are about seven times more important than sea level rise in Seaside Sparrows choosing their nesting location. Her research was published today in The Condor: Ornithological Applications.

Luckily, even though Georgia is expected to get one meter (three feet) of sea level rise by 2100—further squeezing the seaside sparrow habitat—there is hope. Hunter says that there is a chance that if humans can lessen the predator impact by putting fencing or modified cages around nesting areas, they might be able to encourage sparrows to move to higher ground. The research could also help other wildlife management teams plan out a future that keeps other birds living high and dry.

Danmark får ingen unge kongeørne i år

Jan Skriver 12 juli 2017)

De fire ynglende kongeørnepar i Nordjylland, der huser den samlede danske bestand, har i år deres ringeste ynglesæson nogensinde. For første gang i knap 20 år glipper det med frugtbarhed blandt de store rovfugle. Koldt vejr, alderdom og æggetyve blandt rovdyr kan være blandt forklaringerne på den golde sæson

Efter knap to årtier med frugtbarhed og stor stabilitet på hjemmefronten blandt Danmarks ynglende kongeørne ender 2017 som en sæson uden nyt liv.

Det er formentlig et sammenfald af uheldige omstændigheder, som bevirker, at der ikke kommer unge danske kongeørne på vingerne denne sommer. Og der er næppe grund til panik på artens vegne de kommende år, mener ornitologen Tscherning Clausen, der er Dansk Ornitologisk Forenings (DOF) artscaretaker for kongeørnen. Han samler alle data om ørnene, og sammen med fire redekoordinatorer holder han et vågent øje med udviklingen i bestanden.

”Indtil i år har de danske kongeørne været usædvanligt frugtbare, hvis man for eksempel sammenligner med deres svenske artsfæller. De danske ørne har indtil 2017 fået unger på vingerne 18 år i træk. At det glipper i år, kan måske skyldes et meget koldt vejrlig netop i den periode, hvor ørneæggene klækkede. Det kan også spille ind, at alderen begynder at trykke hos i hvert fald et af parrene. Og måske spiller rovdyr som mårer en rolle som æggerøvere. Vi har på ørne-webben hos DOF set, at en husmår er i stand til at kravle op i en havørnerede og æde æggene. Det samme kan ske for kongeørne”, siger Tscherning Clausen, der påpeger, at store rovfugle ofte springer en sæson over, uden at det nødvendigvis påvirker deres tilstedeværelse året efter på et givent territorium.

Svenske ørne holder pauser

”Fra Sverige ved vi, at kongeørne ganske ofte tager en pause med ynglen. Nogle gange kan de springe en sæson over hvert andet eller tredje år. Her må vi sige, at de danske ørne til sammenligning har været ekstremt stabile og frugtbare lige siden artens indvandring. For eksempel har ørneparret i Høstemark Skov i Lille Vildmose fostret en flyvefærdig unge 14 år i træk. I år er første sæson, det glipper for parret, hvor fuglene er omkring 20 år gamle. Selv om kongeørne formentlig kan blive op imod 25-30 år i naturen og i fangenskab endnu ældre, kan alderen måske begynde at resultere i en ringere frugtbarhed hos Høstemarkfuglene”, siger Tscherning Clausen.

Lovende start, skidt finale

Tidligt på sæsonen 2017 så det ellers lovende ud for de fire kongeørnepar i henholdsvis Store Vildmose, Hals Nørreskov samt Høstemark Skov og Tofte Skov i Lille Vildmose, oplyser DOF’s artscaretaker.

Det nye ynglepar, der i 2016 etablerede sig i Store Vildmose, byggede i år en ny rede, men parret opgav tidligt 2017-sæsonen. I Hals Nørreskov, hvor ørnene har ynglet siden 2007, opgav parret i begyndelsen af juni.

Også i Tofte Skov, hvor et nyetableret par byggede rede, og i Høstemark Skov, hvor de erfarne ørne residerer, tegnede det godt tidligt på foråret.

”Fælles for alle parrene har været, at de formentlig har nået at lægge æg og ruge en tid, inden det er gået galt. På sin vis er det ikke overraskende, at de nyetablerede ynglepar i Store Vildmose og det i Tofte Skov mislykkes med familielivet. Det ser man ofte hos store rovfugle. Men vi er overraskede over, at de veletablerede og meget stedfaste ørne i Hals og Høstemark fejler i år”, siger Tscherning Clausen.

To nordjyske revirer på vej

To af fire unge kongeørne, som i forskningens tjeneste er udstyret med GPS-sendere, sender fortsat data om deres færden i landskabet.

Begge disse fugle giver på sin vis løfter om fremtidig frugtbarhed, for de opholder sig meget stabilt i velegnede yngleterræner for kongeørne.

”Den ene af de GPS-mærkede ørne har længe holdt til i moserne nord for Frederikshavn, hvor Råbjerg Moses store uforstyrrede flader må betragtes som et realistisk kommende fast revir for kongeørn. Også den anden GPS-ørn har realistiske muligheder for at etablere sig i det område, hvor den længe har holdt til. Det er nemlig i Hals Sønderskov, der ligesom Hals Nørreskov må siges at være et gæstfrit ørneteræn”, siger Tscherning Clausen.

Nye ørneterræner i sigte

Trods den ringe sæson 2017 har de danske kongeørne gjort deres til at give arten luft under vingerne. I alt er der fostret 37 udfløjne unger i Danmark i perioden 1998-2016. Der menes at være plads, føde og territorier til måske en halv snes kongeørnepar i det danske landskab.

Ovstrup Hede ved Herning og Borris Hede øst for Skjern er realistiske mulige ynglesteder. Også Randbøl Hede og Harrild Hede i Sydjylland, der tidligere har haft besøg af kongeørne, er potentielle yngleområder.

Der skønnes også at være muligheder for flere par kongeørne i Thy, Hanherred, og i de store hedeplantager i Midtjylland. Også Vendsyssel kan komme yderligere med som ørneterræn, blandt andet i Jyske Ås-området.