Agricultural land abandonment is recognized as a major environmental threat in Europe, being particularly pronounced in south-eastern Europe, where knowledge on its effects is limited. Taking the ...Balkan Peninsula as a case study, we investigated agricultural abandonment impact on passerine communities at regional level. We set up a standard methodology for site selection (70 sites) and data collection, along a well-defined forest-encroachment gradient that reflects land abandonment in four countries: Albania, Bulgaria, Croatia and Greece. Regardless the different socio-economic and political histories in the Balkans that led to diverse land abandonment patterns in space and time, rural abandonment had a consistent negative effect on bird communities, while regional-level analysis revealed patterns that were hidden at local level. The general trends were an increase of forest-dwelling bird species at the expense of farmland birds, the decline of overall bird species richness, as well as the decline of Species of European Conservation Concern (SPECs) richness and abundance. Many farmland bird species declined with land abandonment, whereas few forest species benefited from the process. In conclusion, our results support CAP towards hampering rural land abandonment and preserving semi-open rural mosaics in remote upland areas, using a suite of management measures carefully tailored to local needs. The maintenance of traditional rural landscapes should be prioritized in the Balkans, through the timely identification of HNV farmland that is most prone to abandonment. We also suggest that coordinated transnational research is needed, for a better assessment of conservation options in remote rural landscapes at European scale, including the enhancement of wild grazers' populations as an alternative in areas where traditional land management is rather unlikely to be re-established.
•Rural land abandonment negatively affects bird communities in S.E. Europe.•A decline of farmland and SPEC species observed along the abandonment gradient.•Regional-level analysis revealed bird diversity patterns hidden at local level.•We support Common Agricultural Policies against rural land abandonment.
Many populations of long‐distance migrants are declining and there is increasing evidence that declines may be caused by factors operating outside the breeding season. Among the four vulture species ...breeding in the western Palaearctic, the species showing the steepest population decline, the Egyptian Vulture Neophron percnopterus, is a long‐distance migrant wintering in Africa. However, the flyways and wintering areas of the species are only known for some populations, and without knowledge of where mortality occurs, effective conservation management is not possible. We tracked 19 juvenile Egyptian Vultures from the declining breeding population on the Balkan Peninsula between 2010 and 2014 to estimate survival and identify important migratory routes and wintering areas for this species. Mortality during the first autumn migration was high (monthly survival probability 0.75) but mortality during migration was exclusively associated with suboptimal navigation. All birds from western breeding areas and three birds from central and eastern breeding areas attempted to fly south over the Mediterranean Sea, but only one in 10 birds survived this route, probably due to stronger tailwind. All eight birds using the migratory route via Turkey and the Middle East successfully completed their first autumn migration. Of 14 individual and environmental variables examined to explain why juvenile birds did or did not successfully complete their first migration, the natal origin of the bird was the most influential. We speculate that in a declining population with fewer experienced adults, an increasing proportion of juvenile birds are forced to migrate without conspecific guidance, leading to high mortality as a consequence of following sub‐optimal migratory routes. Juvenile Egyptian Vultures wintered across a vast range of the Sahel and eastern Africa, and had large movement ranges with core use areas at intermediate elevations in savannah, cropland or desert. Two birds were shot in Africa, where several significant threats exist for vultures at continental scales. Given the broad distribution of the birds and threats, effective conservation in Africa will be challenging and will require long‐term investment. We recommend that in the short term, more efficient conservation could target narrow migration corridors in southern Turkey and the Middle East, and known congregation sites in African wintering areas.
One approach to stabilise small and declining populations is to breed individuals in captivity and release them into the wild to reinforce existing populations while working to reduce threats. ...Population reinforcement programmes require long‐term commitments to be successful and can divert limited resources from other conservation measures. A rigorous evaluation whether reinforcement can stabilise a population is therefore essential to justify investments.
Many migratory species incur high mortality during their first migration, and releasing captive‐bred birds at an older age may therefore benefit reinforcement programmes for migratory birds. We examine whether a small and declining population of a long‐distance migratory raptor—the Egyptian Vulture Neophron percnopterus—can be stabilised using population reinforcement that reduces mortality during the first migration. We used an integrated population model to evaluate realistic reinforcement and survival improvement scenarios to estimate how many captive‐bred birds would need to be released to stabilise the population.
Survival probability of wild juveniles during their first year (0.296; 95% CI 0.234–0.384) was too low for a stable population (population growth rate 0.949; 95% CI 0.940–0.956), but captive‐bred juveniles released in their second calendar year had improved survival (0.566; 95% CI 0.265–0.862) during their first year in the wild.
Reinforcement of 15 birds per year for 30 years was insufficient to achieve a neutral or positive population growth rate. However, reinforcement reduced the probability of extinction by 2049 from 48% without reinforcement to <1% if 12 or more birds were released every year for 30 years. A 6% increase in annual survival probability would likely lead to a stable population without any reinforcement.
Synthesis and applications. Although releasing captive‐bred birds can reduce high juvenile mortality during first migration and assist in postponing local extinction, further improvements of survival in the wild are required to safeguard a migratory population where threats in the wild will persist for decades despite management.
Translated Περίληψη
Μία προσέγγιση που στοχεύει στη σταθεροποίηση μικρών και μειούμενων πληθυσμών είναι η αναπαραγωγή ατόμων σε αιχμαλωσία και στη συνέχεια η απελευθέρωσή τους στην φύση για την ενδυνάμωση των υπαρχόντων πληθυσμών, ενώ παράλληλα συνεχίζονται οι διαχειριστικές δράσεις που στοχεύουν στον περιορισμό των απειλών. Τέτοια προγράμματα ενδυνάμωσης πληθυσμών, για να είναι επιτυχημένα, απαιτούν μακροπρόθεσμη δέσμευση και μπορούν να εκτρέψουν τους ήδη περιορισμένους πόρους από άλλα μέτρα διατήρησης. Είναι επομένως απαραίτητη μια διεξοδική αξιολόγηση του κατά πόσον οι δράσεις ενδυνάμωσης μπορούν να οδηγήσουν έναν πληθυσμό σε σταθεροποίηση, έτσι ώστε πιθανές επενδύσεις σε τέτοιες δράσεις να είναι δικαιολογημένες.
Πολλά μεταναστευτικά είδη πουλιών υφίστανται υψηλή θνησιμότητα κατά το πρώτο τους ταξίδι οπότε η απελευθέρωση ατόμων που έχουν αναπαραχθεί σε αιχμαλωσία αφού έχουν φτάσει σε μεγαλύτερη ηλικία μπορεί να ωφελήσει προγράμματα ενδυνάμωσης που στοχεύουν πληθυσμούς μεταναστευτικών ειδών. Εδώ, εξετάζουμε εάν ένας μικρός και μειούμενος πληθυσμός ενός μεταναστευτικού είδους αρπακτικού ‐ του Ασπροπάρη (Neophron percnopterus) ‐ μπορεί να σταθεροποιηθεί μέσω δράσεων ενίσχυσης που μειώνουν τη θνησιμότητα κατά την πρώτη μετανάστευση. Χρησιμοποιήσαμε πληθυσμιακά μοντέλα για να αξιολογήσουμε ρεαλιστικά σενάρια ενδυνάμωσης και αύξησης της επιβίωσης ώστε να εκτιμήσουμε πόσα άτομα που έχουν αναπαραχθεί σε αιχμαλωσία θα πρέπει να απελευθερωθούν για να επιτευχθεί η σταθεροποίηση του πληθυσμού.
Η πιθανότητα επιβίωσης των άγριων νεαρών ατόμων κατά το πρώτο έτος της ζωής τους (0,296, 95% CI 0,234 – 0,384) ήταν πολύ χαμηλή για να οδηγήσει σε έναν σταθερό πληθυσμό (ρυθμός αύξησης πληθυσμού 0,949, 95% CI 0,940 –0,956), αλλά τα νεαρά άτομα που είχαν αναπαραχθεί σε αιχμαλωσία και απελευθερώθηκαν στον δεύτερο χρόνο της ζωής τους, έδειξαν αυξημένη επιβίωση (0,566, 95% CI 0,265 – 0,886) κατά τη διάρκεια του πρώτου έτους τους στη φύση.
Η ενδυνάμωση του πληθυσμού με την απελευθέρωση 15 πουλιών ετησίως για 30 χρόνια δεν επαρκεί για την επίτευξη είτε σταθερού είτε θετικού ρυθμού αύξησης του πληθυσμού. Ωστόσο, η δράση ενδυνάμωσης μπορεί να μειώσει την πιθανότητα εξαφάνισης από 48% σε λιγότερο από 1% έως το 2049, εάν 12 ή περισσότερα πουλιά απελευθερώνονταν κάθε χρόνο για 30 χρόνια. Επίσης, εάν η ετήσια πιθανότητα επιβίωσης αυξανόταν κατά 8% θα οδηγούσε σε έναν σταθερό πληθυσμό χωρίς να χρειάζεται καμία δράση ενίσχυσης.
Σύνθεση και εφαρμογές. Παρόλο που η ενδυνάμωση του πληθυσμού μπορεί να μειώσει την υψηλή θνησιμότητα των νεαρών ατόμων κατά την πρώτη τους μετανάστευση και να βοηθήσει στην αναστολή μιας τοπικής εξαφάνισης, απαιτείται περαιτέρω βελτίωση της επιβίωσης τους στην φύση για την διασφάλιση ενός μεταναστευτικού πληθυσμού ο οποίος θα συνεχίσει να αντιμετωπίζει απειλές για δεκαετίες παρά τη διαχείριση.
Although releasing captive‐bred birds can reduce high juvenile mortality during first migration and assist in postponing local extinction, further improvements of survival in the wild are required to safeguard a migratory population where threats in the wild will persist for decades despite management.
Long‐distance migrations are among the most physically demanding feats animals perform. Understanding the potential costs and benefits of such behaviour is a fundamental question in ecology and ...evolution. A hypothetical cost of migration should be outweighed by higher productivity and/or higher annual survival, but few studies on migratory species have been able to directly quantify patterns of survival throughout the full annual cycle and across the majority of a species’ range.
Here, we use telemetry data from 220 migratory Egyptian vultures Neophron percnopterus, tracked for 3,186 bird months and across approximately 70% of the species’ global distribution, to test for differences in survival throughout the annual cycle.
We estimated monthly survival probability relative to migration and latitude using a multi‐event capture–recapture model in a Bayesian framework that accounted for age, origin, subpopulation and the uncertainty of classifying fates from tracking data.
We found lower survival during migration compared to stationary periods (β = −0.816; 95% credible interval: −1.290 to −0.318) and higher survival on non‐breeding grounds at southern latitudes (<25°N; β = 0.664; 0.076–1.319) compared to on breeding grounds. Survival was also higher for individuals originating from Western Europe (β = 0.664; 0.110–1.330) as compared to further east in Europe and Asia, and improved with age (β = 0.030; 0.020–0.042). Anthropogenic mortalities accounted for half of the mortalities with a known cause and occurred mainly in northern latitudes. Many juveniles drowned in the Mediterranean Sea on their first autumn migration while there were few confirmed mortalities in the Sahara Desert, indicating that migration barriers are likely species‐specific.
Our study advances the understanding of important fitness trade‐offs associated with long‐distance migration. We conclude that there is lower survival associated with migration, but that this may be offset by higher non‐breeding survival at lower latitudes. We found more human‐caused mortality farther north, and suggest that increasing anthropogenic mortality could disrupt the delicate migration trade‐off balance. Research to investigate further potential benefits of migration (e.g. differential productivity across latitudes) could clarify how migration evolved and how migrants may persist in a rapidly changing world.
In a large tracking study of an endangered migratory bird, the authors found lower survival during migration compared to stationary periods and higher survival on non‐breeding as compared to on breeding grounds. They conclude that the cost associated with migration could be offset by higher non‐breeding survival at lower latitudes. The photo is by Kayahan Ağırkaya, KuzeyDoğa.
Assessing the effectiveness of conservation measures to reverse population declines is essential to evaluate management strategies. Management solutions such as direct protection or supplementary ...feeding typically aim at reducing mortality or increasing productivity, but demonstrating such demographic consequences of adopted management is often difficult. Here we assess the effectiveness of large-scale management actions aimed at the conservation of an endangered vulture on the Balkan Peninsula by extending a novel analysis to estimate seasonal adult survival from observations of unmarked individuals. We monitored Egyptian Vulture Neophron percnopterus breeding success and territory occupancy over 11years in three countries during which both nest guarding and supplementary feeding were carried out. We found little evidence that nest guarding and supplementary feeding increased breeding propensity (mean=0.88±0.32 standard deviation, n=463), breeding success (0.82±0.39), or the number of fledglings raised by successful pairs (1.3±0.74). We estimated adult survival during the 23-week breeding season (mean=0.936, 95% credible interval 0.889–0.968) and found no significant increase due to management. In the last 13years 43 dead adult birds have been found during the breeding season, and 77% of confirmed mortalities were due to poisoning. Overall, the current management measures may have so far failed to halt ongoing population declines because the beneficial effects are insufficient to offset the loss of adult birds for example due to poisoning. We suggest that additional measures to slow the decline of Egyptian Vultures in the Balkans are required. In the short term, we urge governments to enforce anti-poison regulations that already exist. In the medium term, alternative approaches need to be developed that reduce the use of poisons and the associated accidental mortality of vultures and other wildlife species.
Migrant birds face a number of threats throughout their annual cycle, including persecution, collision with energy infrastructure, and habitat and climate change. A key challenge for the conservation ...of migrants is the identification of important habitat, including migratory concentration areas, because species survival rates may be determined by events in geographically very limited areas. Remote‐tracking technology is facilitating the identification of such critical habitat, although the strategic identification of important sites and incorporation of such knowledge in conservation planning remains limited. We tracked 45 individuals of an endangered, soaring migrant (Egyptian vulture Neophron percnopterus), over 75 complete migrations that traversed three continents along the Red Sea Flyway. We summarize and contextualize migration statistics by season and age class, including migration start, midpoint, and end dates, as well as linear and cumulative migration distance, migration duration and speed, and route straightness. Then, using dynamic Brownian bridge movement models, we quantified space use to identify the most important migratory bottlenecks and high‐use areas on the flyway. These areas each accounted for < 5% of the overall movement range of the tracked birds, yet > 20% of all tracks passed through bottlenecks, and > 50% of the overall vulture time spent on migration fell within high‐use areas. The most important sites were located at the southeastern Red Sea coast and Bab‐el‐Mandeb Strait (Saudi Arabia, Yemen, Djibouti), the Suez Canal zone (Egypt), and the Gulf of Iskenderun (Turkey). Discouragingly however, none of the area within the major migratory bottlenecks was protected and < 13% of the high‐use areas were protected. This demonstrates a very concerning gap in the protected area network for migratory soaring birds along the Red Sea Flyway. Because reducing threats at migratory concentrations can be a very efficient approach to protect populations, our work provides clear guidelines where conservation investment is urgently needed to benefit as many as 35 migratory soaring‐bird species that regularly use the Red Sea Flyway.
To gain insight into the question of which vegetation characteristics have the most influence on avian assemblages in late-successional forests, the habitat preferences of bird-guilds in old-growth ...endemic forests of Macedonian pine were studied over 3 years in the Pirin National Park, Bulgaria. Bird–habitat relationships were investigated by comparing vegetation characteristics, and bird species richness, diversity, abundance, and guild structure of birds (determined according to food type, foraging and nesting sites) between mature (60–100 years old) and over-mature (>120 years old) Macedonian pine forest stands. Studied forest age-classes differed mainly by the density, height and diameter of trees, and the amount of dead wood. The first one of these parameters decreased and the latter two parameters increased with the forest succession. The difference in the vegetation structure affected the abundance of bird-guilds and thus, the overall bird abundance and the structure of avian assemblages within Macedonian pine forests. There was no significant difference in bird diversity among studied forest age-classes, but the overall bird abundance increased with forest maturation. Analyzed by study plots, species richness was higher in over-mature forests, but at cluster level, there was no significant difference between mature and over-mature forest age-classes. Half of the studied (insectivorous, hole- and ground-nesters, bark- and canopy-foraging bird species) guilds were more abundant in over-mature forests, while there was no bird-guild exhibiting a preference for mature forest stands. The abundances of bird-guilds were correlated with tree height, diameter at breast height and the amount of dead wood between the studied forest age-classes and this might explain their preferences for over-mature pine forests. Therefore, for future sustainable management of these endemic forests and the conservation of their avifauna, efforts should focus on protecting the remaining native old-growth forest stands and the importance of the structure of Macedonian pine forests on their bird assemblages should be considered in forestry practices.
Vultures constitute globally the most rapidly declining group of birds. Across their wide distribution range, they share common ecological functions and unfavourable conservation status while being ...associated with varying habitats, lifestyles, cultural standing, and threats. We reveal conceptualisations about the emblematic yet critically endangered Egyptian vulture along its migratory flyway from the Balkans through the Middle East to Africa. Information was gathered through interviews, focus group discussions, and market surveys, with 420 people in 11 participating countries contributing overall. Our results showed that all vultures are recognised primarily for the environmental cleaning services, but the level of awareness differs between countries. Τhe Egyptian vulture has some perceptual advantages based on its white color, migratory nature, and endangered conservation status. This underlines its suitability as a charismatic flagship species that can potentially benefit other vulture species and thus enforce broader vulture conservation initiatives.
One of the primary goals of conservation translocation programs should be the maintenance of both population demographic stability and genetic diversity. Here, we provide genetic management ...recommendations to inform a population reinforcement of the declining Egyptian Vulture population in the Balkans. Specifically, we examined whether the number of released individuals is sufficient to prevent genetic diversity loss due to random genetic drift and what the origin of the individuals should be that comprise the captive breeding pool. To this aim, we estimated and assessed genetic diversity levels and genetic structure of Egyptian Vulture populations across much of the species’ range using both neutral and non-neutral candidate loci involved in migration. We then evaluated the effects of the currently proposed population management scheme and candidate source populations on retaining allelic diversity. Our results show low differentiation values among populations and absence of genetic structure which point to past high gene flow. Furthermore, there was no predicted significant impact of different source populations on the genetic diversity of the recipient Balkan population. We also found that the declining Egyptian Vulture population in the Balkans still retains high levels of genetic diversity and therefore genetic diversity restoration is not currently needed. However, without any management, diversity is likely to decrease fast because of increased genetic drift as the population size continues to decline. Population reinforcement with nine birds per year for 20 years would provide sufficient demographic support for the population to retain > 85% of rare allelic diversity. Birds originating from the Balkans would ensure ecological and behavioral similarity and thus would be the best option for reinforcement. Nevertheless, our results demonstrate that to prevent further population contraction and loss of adaptive alleles, releasing individuals of different origin would also be appropriate.
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