Genetic analysis of Saker Falcon (Falco cherrug) subspecies

Two subspecies of Saker Falcon are commonly accepted - Western (Falco cherrug cherrug) and Eastern (Falco cherrug milvipes), which are differentiated by their distribution range and phenotype. In Bulgaria, Western Saker Falcons are breeding ex situ in the Wildlife Rehabilitation and Breeding Centre, part of Green Balkans - Stara Zagora NGO, with the aim of restoring the nesting population of the species in the country and both Western and Eastern - in the Breeding Centre for Birds of Prey in Burgas for the purpose of sale for the needs of falconry in the country and abroad. In 2021, a total of 115 birds from the two breeding centres were sampled. The samples were analysed in Bielefeld University (Germany) at nine microsatellite loci. Structure analyses were performed to establish the optimal explanatory number of groups. We compared the putative genetic groups with the known/expected origin of falcons. A separation in two groups best explained the allelic variation between samples. Out of 68 Saker Falcons with putatively Eastern origin, 66 were ascribed to genetic group 2 and two falcons had unclear, mixed or hybrid genetic fingerprints. Out of 42 Sakers with putatively Western origin, 33 were ascribed to genetic group 1, seven to genetic group 2 and two individuals appeared to have a mixed signature of genetic groups 1 and 2 with dominating alleles of group 2. Five known hybrids were scored as mixed signature with dominating genetic cluster 2. This suggests that the two (Eastern and Western) populations of Saker Falcon origin suggested by the subspecies' definitions are also adequate to be considered in breeding programmes. Genetic cluster 1 might represent the ancestral alleles shared with other falcons, while specific novel alleles allow the discrimination of secured Eastern Sakers (group 2), while these populations may be occasionally invaded by individuals from the west

Blood parasites in vectors reveal a united blackfly community in the upper canopy.

Chakarov N, Kampen H, Wiegmann A, Werner D, Bensch S. Blood parasites in vectors reveal a united blackfly community in the upper canopy. Parasites & vectors. 2020;13(1): 309.BACKGROUND: The behaviour of blood-sucking arthropods is a crucial determinant of blood protozoan distribution and hence of host-parasite coevolution, but it is very challenging to study in the wild. The molecular identification of parasite lineages in vectors can be a useful key to understand the behaviour and transmission patterns realised by these vectors.; METHODS: In this study, we collected blackflies around nests of three raptor species in the upper forest canopy in central Europe and examined the presence of vertebrate DNA and haemosporidian parasites in them. We molecularly analysed 156 blackfly individuals, their vertebrate blood meals, and the haemosporidian parasite lineages they carried.; RESULTS: We identified nine species of Simulium blackflies, largely belonging to the subgenera Nevermannia and Eusimulium. Only 1% of the collected specimens was visibly engorged, and only 4% contained remains of host DNA. However, in 29% of the blackflies Leucocytozoon lineages were identified, which is evidence of a previous blood meal on an avian host. Based on the known vertebrate hosts of the recorded Leucocytozoon lineages, we can infer that large and/or abundant birds, such as thrushes, crows, pigeons, birds of prey, owls and tits are the main targets of ornithophilic blackflies in the canopy. Blackfly species contained similar proportions of host group-specific parasite lineages and thus do not appear to be associated with particular host groups.; CONCLUSIONS: The Leucocytozoon clade infecting thrushes, crows, and pigeons present in most represented blackfly species suggests a lack of association between hosts and blackflies, which can increase the probability of host switches of blood parasites. However, the composition of the simuliid species differed between nests of common buzzards, goshawks and red kites. This segregation can be explained by coinciding habitat preferences between host and vector, and may lead to the fast speciation of Leucocytozoon parasites. Thus, subtle ecological preferences and lack of host preference of vectors in the canopy may enable both parasite diversification and host switches, and enforce a habitat-dependent evolution of avian malaria parasites and related haemosporidia

Blood parasite infections in a wild population of ravens (Corvus corax) in Bulgaria

Shurulinkov P, Spasov L, Stoyanov G, Chakarov N. Blood parasite infections in a wild population of ravens (Corvus corax) in Bulgaria. Malaria journal. 2018;17(33): 33.Background: Blood parasites have been studied intensely in many families of avian hosts, but corvids, a particularly cosmopolitan family, remain underexplored. Haemosporidian parasites of the common raven (Corvus corax) have not been studied, although it is the largest, most adaptable, and widespread corvid. Genetic sequence data from parasites of ravens can enhance the understanding of speciation patterns and specificity of haemosporidian parasites in corvids, and shed light how these hosts cope with parasite pressure. Methods: A baited cage trap was used to catch 86 ravens and a nested PCR protocol was used to amplify a 479 bp fragment of the haemosporidian cytochrome b gene from the samples. The obtained sequences were compared with the MalAvi database of all published haemosporidian lineages and a phylogenetic tree including all detected raven parasites was constructed. An examination of blood smears was performed for assessment of infection intensity. Results: Twenty blood parasite lineages were recovered from ravens caught in a wild population in Bulgaria. The prevalence of generalist Plasmodium lineages was 49%, and the prevalence of Leucocytozoon lineages was 31%. Out of 13 detected Leucocytozoon lineages six were known from different corvids, while seven others seem to be specific to ravens. A phylogenetic reconstruction suggests that Leucocytozoon lineages of ravens and other corvids are not monophyletic, with some groups appearing closely related to parasites of other host families. Conclusions: Several different, morphologically cryptic groups of Leucocytozoon parasites appear to infect corvids. Ravens harbour both generalist corvid Leucocytozoon as well as apparently species-specific lineages. The extraordinary breeding ecology and scavenging lifestyle possibly allow ravens to evade vectors and have relatively low blood parasite prevalence compared to other corvids

Genetic diversity and relatedness amongst captive saker falcons (Falco cherrug) in the Green Balkans’ Wildlife Rehabilitation and Breeding Centre in Bulgaria

The globally endangered saker falcon (Falco cherrug) is currently being re-introduced in Bulgaria, where the falcons are bred in captivity and released through the hacking method. We relied on the birds’ pedigree when forming the breeding pairs from 2011. In 2021-2022, we had the opportunity to evaluate our captive population via DNA tests. We performed the first genetic assessment of the sakers in the WRBC through a genome evaluation of the most important founders (n = 12) and, in 2022, we executed a microsatellite analysis on 30 saker falcons from the programme. We compared the results with the known pedigree and history of the saker falcons. The genetic tests helped to assign relatedness to some birds with missing or incomplete pedigrees, indicating the test can complement that information and lead to better management of the captive group. One pair was separated as a precaution as it was indicated by one the tests that the two birds are more closely related than expected. The research could be beneficial to other raptor captive breeding programmes dealing with a similar group composition

Landscape homogenization due to agricultural intensification disrupts the relationship between reproductive success and main prey abundance in an avian predator

Background: Selecting high-quality habitat and the optimal time to reproduce can increase individual fitness and is a strong evolutionary factor shaping animal populations. However, few studies have investigated the interplay between land cover heterogeneity, limitation in food resources, individual quality and spatial variation in fitness parameters. Here, we explore how individuals of different quality respond to possible mismatches between a cue for prey availability (land cover heterogeneity) and the actual fluctuating prey abundance. Results: We analyse timing of breeding and reproductive success in a migratory population of Eurasian kestrels (Falco tinnunculus) breeding in nest-boxes, over a full three-year abundance cycle of main prey (voles), and consider several components of individual quality, including body condition, blood parasite infection, and genetic diversity (n = 448 adults) that act on different time scales. Older individuals, and kestrel parents in higher body condition started egg-laying earlier than younger birds and those in lower body condition. Additionally, egg-laying was initiated earlier during the increase and decrease phases (2011 and 2012) than during the low phase of the vole cycle (2013). Nestling survival (ratio of eggs that fledged successfully) was higher in early nests and in heterogeneous landscapes (i.e., mosaic of different habitat types), which was evident during the increase and decrease phases of the vole cycle, but not during the low vole year. Conclusions: We found a strong positive effect of landscape heterogeneity on nestling survival, but only when voles were relatively abundant, whereas a difference in the timing of breeding related to territory landscape heterogeneity was not evident. Therefore, landscape heterogeneity appeared as the main driver of high reproductive performance under favourable food conditions. Our results show that landscape homogenization linked to agricultural intensification disrupts the expected positive effect of vole abundance on reproductive success of kestrels.</div

Early sexual dimorphism in the developing gut microbiome of northern elephant seals

The gut microbiome is an integral part of a species’ ecology, but we know little about how host characteristics impact its development in wild populations. Here, we explored the role of such intrinsic factors in shaping the gut microbiome of northern elephant seals during a critical developmental window of six weeks after weaning, when the pups stay ashore without feeding. We found substantial sex-differences in the early-life gut microbiome, even though males and females could not yet be distinguished morphologically. Sex and age both explained around 15% of the variation in gut microbial beta diversity, while microbial communities sampled from the same individual showed high levels of similarity across time, explaining another 40% of the variation. Only a small proportion of the variation in beta diversity was explained by health status, assessed by full blood counts, but clinically healthy individuals had a greater microbial alpha diversity than their clinically abnormal peers. Across the post-weaning period, the northern elephant seal gut microbiome was highly dynamic. We found evidence for several colonisation and extinction events as well as a decline in Bacteroides and an increase in Prevotella, a pattern that has previously been associated with the transition from nursing to solid food. Lastly, we show that genetic relatedness was correlated with gut microbiome similarity in males but not females, again reflecting early sex-differences. Our study represents a naturally diet-controlled and longitudinal investigation of how intrinsic factors shape the early gut microbiome in a species with extreme sex differences in morphology and life history

Territory quality and plumage morph predict offspring sex ratio variation in a raptor

Parents may adapt their offspring sex ratio in response to their own phenotype and environmental conditions. The most significant causes for adaptive sex-ratio variation might express themselves as different distributions of fitness components between sexes along a given variable. Several causes for differential sex allocation in raptors with reversed sexual size dimorphism have been suggested. We search for correlates of fledgling sex in an extensive dataset on common buzzards Buteo buteo, a long-lived bird of prey. Larger female offspring could be more resource-demanding and starvation-prone and thus the costly sex. Prominent factors such as brood size and laying date did not predict nestling sex. Nonetheless, lifetime sex ratio (LSR, potentially indicative of individual sex allocation constraints) and overall nestling sex were explained by territory quality with more females being produced in better territories. Additionally, parental plumage morphs and the interaction of morph and prey abundance tended to explain LSR and nestling sex, indicating local adaptation of sex allocation However, in a limited census of nestling mortality, not females but males tended to die more frequently in prey-rich years. Also, although females could have potentially longer reproductive careers, a subset of our data encompassing full individual life histories showed that longevity and lifetime reproductive success were similarly distributed between the sexes. Thus, a basis for adaptive sex allocation in this population remains elusive. Overall, in common buzzards most major determinants of reproductive success appeared to have no effect on sex ratio but sex allocation may be adapted to local conditions in morph-specific patterns

De novo assembly of the dual transcriptomes of a polymorphic raptor species and its malarial parasite

Pauli M, Chakarov N, Rupp O, et al. De novo assembly of the dual transcriptomes of a polymorphic raptor species and its malarial parasite. BMC Genomics. 2015;16(1): 1038

Mesopredator Release by an Emergent Superpredator: A Natural Experiment of Predation in a Three Level Guild

Chakarov N, Krüger O. Mesopredator Release by an Emergent Superpredator: A Natural Experiment of Predation in a Three Level Guild. PLoS ONE. 2010;5(12): e15229.Background: Intraguild predation (IGP) is widespread but it is often neglected that guilds commonly include many layers of dominance within. This could obscure the effects of IGP making unclear whether the intermediate or the bottom mesopredator will bear higher costs from the emergence of a new top predator. Methodology/Principal Findings: In one of the most extensive datasets of avian IGP, we analyse the impact of recolonization of a superpredator, the eagle owl Bubo bubo on breeding success, territorial dynamics and population densities of two mesopredators, the northern goshawk Accipiter gentilis and its IG prey, the common buzzard Buteo buteo. The data covers more than two decades and encompass three adjacent plots. Eagle owls only recolonized the central plot during the second decade, thereby providing a natural experiment. Both species showed a decrease in standardized reproductive success and an increase in brood failure within 1.5 km of the superpredator. During the second decade, territory dynamics of goshawks was significantly higher in the central plot compared to both other plots. No such pattern existed in buzzards. Goshawk density in the second decade decreased in the central plot, while it increased in both other plots. Buzzard density in the second decade rapidly increased in the north, remained unchanged in the south and increased moderately in the center in a probable case of mesopredator release. Conclusions/Significance: Our study finds support for top-down control on the intermediate mesopredator and both top-down and bottom-up control of the bottom mesopredator. In the face of considerable costs of IGP, both species probably compete to breed in predator-free refugia, which get mostly occupied by the dominant raptor. Therefore for mesopredators the outcome of IGP might depend directly on the number of dominance levels which supersede them