Non-passerine Bird Research Articles

Detection of a new avian bornavirus in barn owl (Tyto alba) by pan-viral microarray

A barn owl (Tyto alba) died with neurological signs compatible with a viral infection. After discarding other possible infections caused by circulating viruses in the area, analysis of the central nervous system using a pan-viral microarray revealed hybridization to canary bornavirus 2 (CnBV-2). Subsequent sequence analysis confirmed the presence of a virus sharing more than 83% identity with CnBV-2. Surprisingly, the new sequence corresponds to a new virus, here named Barn owl Bornavirus 1 (BoBV-1), within the Orthobornavirus serini species. Moreover, it is the first member of this species that has been detected in a non-passerine bird, indicating that Orthobornavirus serini species comprises viruses with a wider range of hosts than previously presumed. The use of this microarray has proven to be an excellent tool for viral detection in clinical samples, with capacity to detect new viral variants. This allows the diagnosis of a great range of viruses, which can cause similar disease symptoms and which identification by PCR methods might be tedious, probably unsuccessful and, in the long run, expensive. This platform is highly useful for a fast and precise viral detection, contributing to the improvement of diagnostic methods.

High functional allelic diversity and copy number in both MHC classes in the common buzzard

BackgroundThe major histocompatibility complex (MHC), which encodes molecules that recognize various pathogens and parasites and initiates the adaptive immune response in vertebrates, is renowned for its exceptional polymorphism and is a model of adaptive gene evolution. In birds, the number of MHC genes and sequence diversity varies greatly among taxa, believed due to evolutionary history and differential selection pressures. Earlier characterization studies and recent comparative studies suggest that non-passerine species have relatively few MHC gene copies compared to passerines. Additionally, comparative studies that have looked at partial MHC sequences have speculated that non-passerines have opposite patterns of selection on MHC class I (MHC-I) and class II (MHC-II) loci than passerines: namely, greater sequence diversity and signals of selection on MHC-II than MHC-I. However, new sequencing technology is revealing much greater MHC variation than previously expected while also facilitating full sequence variant detection directly from genomic data. Our study aims to take advantage of high-throughput sequencing methods to fully characterize both classes and domains of MHC of a non-passerine bird of prey, the common buzzard (Buteo buteo), to test predictions of MHC variation and differential selection on MHC classes.ResultsUsing genetic, genomic, and transcriptomic high-throughput sequencing data, we established common buzzards have at least three loci that produce functional alleles at both MHC classes. In total, we characterize 91 alleles from 113 common buzzard chicks for MHC-I exon 3 and 41 alleles from 125 chicks for MHC-IIB exon 2. Among these alleles, we found greater sequence polymorphism and stronger diversifying selection at MHC-IIB exon 2 than MHC-I exon 3, suggesting differential selection pressures on MHC classes. However, upon further investigation of the entire peptide-binding groove by including genomic data from MHC-I exon 2 and MHC-IIA exon 2, this turned out to be false. MHC-I exon 2 was as polymorphic as MHC-IIB exon 2 and MHC-IIA exon 2 was essentially invariant. Thus, comparisons between MHC-I and MHC-II that included both domains of the peptide-binding groove showed no differences in polymorphism nor diversifying selection between the classes. Nevertheless, selection analysis indicates balancing selection has been acting on common buzzard MHC and phylogenetic inference revealed that trans-species polymorphism is present between common buzzards and species separated for over 33 million years for class I and class II.ConclusionsWe characterize and confirm the functionality of unexpectedly high copy number and allelic diversity in both MHC classes of a bird of prey. While balancing selection is acting on both classes, there is no evidence of differential selection pressure on MHC classes in common buzzards and this result may hold more generally once more data for understudied MHC exons becomes available.

Using de novo genome assembly and high-throughput sequencing to characterize the MHC region in a non-model bird, the Eurasian coot

Genes of the Major Histocompatibility Complex (MHC) form a key component of vertebrate adaptive immunity, as they code for molecules which bind antigens of intra- and extracellular pathogens (MHC class I and II, respectively) and present them to T cell receptors. In general, MHC genes are hyper-polymorphic and high MHC diversity is often maintained within natural populations (via balancing selection) and within individuals (via gene duplications). Because of its complex architecture with tandems of duplicated genes, characterization of MHC region in non-model vertebrate species still poses a major challenge. Here, we combined de novo genome assembly and high-throughput sequencing to characterize MHC polymorphism in a rallid bird species, the Eurasian coot Fulica atra. An analysis of genome assembly indicated high duplication rate at MHC-I, which was also supported by targeted sequencing of peptide-binding exons (at least five MHC-I loci genotyped). We found high allelic richness at both MHC-I and MHC-II, although signature of diversifying selection and recombination (gene conversion) was much stronger at MHC-II. Our results indicate that Eurasian coot retains extraordinary polymorphism at both MHC classes (when compared to other non-passerine bird species), although they may be subject to different evolutionary mechanism.

Dear-enemy effect between two sympatric bird species

Although interspecific interactions appear to be less competitive than intraspecific ones, interspecific territoriality is much more frequent and more stable than is commonly believed. When territorial interactions between competing species are repeated, discrimination between heterospecifics can allow for a more precise allocation of resources and risk. An example of such a strategic approach is the dear-enemy effect, according to which individuals are less aggressive to familiar than unfamiliar individuals. We investigated the occurrence of the dear-enemy effect in territorial interactions between two nonpasserine bird species: water rail, Rallus aquaticus , and little crake, Zapornia parva , which compete for food and nest site resources. We used a cross-species playback experiment where water rails received calls of strangers and neighbouring little crakes, while little crakes received calls of water rails in the same manner. In addition, each focal pair was exposed to control calls of little grebes, Tachybaptus ruficollis . In both species, territory holders produced more calls in response to heterospecific strangers than heterospecific neighbours, and the response to control stimuli was the weakest. Furthermore, little crakes often approached and attacked the loudspeakers and mostly when they heard the calls of stranger water rails. Our results indicate that both species were able to distinguish not only each other from the control species, but also specific individuals of the second species. In line with the dear-enemy effect, water rails and little crakes adjusted their territorial response according to the intruder's status, being most aggressive to heterospecific strangers. These findings suggest an adaptive territorial response to resource competition that is commonly confirmed among conspecifics but rarely between individuals of different species. • We studied the dear-enemy effect between two competing bird species. • Water rails and little crakes recognized specific individuals of the other species. • Both species responded with lower vocal intensity to heterospecific neighbours. • Stronger nonvocal response to stranger calls was observed only in little crakes.

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How hornbills handle heat: sex-specific thermoregulation in the southern yellow-billed hornbill.

At a global scale, thermal physiology is correlated with climatic variables such as temperature and aridity. There is also evidence that thermoregulatory traits vary with fine-scale microclimate, but this has received less attention in endotherms. Here, we test the hypothesis that avian thermoregulation varies with microclimate and behavioural constraints in a non-passerine bird. Male and female southern yellow-billed hornbills (Tockus leucomelas) experience markedly different microclimates while breeding, with the female sealing herself into a tree cavity and moulting all her flight feathers during the breeding attempt, becoming entirely reliant on the male for provisioning. We examined interactions between resting metabolic rate (RMR), evaporative water loss (EWL) and core body temperature (Tb) at air temperatures (Ta) between 30°C and 52°C in male and female hornbills, and quantified evaporative cooling efficiencies and heat tolerance limits. At thermoneutral Ta, neither RMR, EWL nor Tb differed between sexes. At Ta >40°C, however, RMR and EWL of females were significantly lower than those of males, by ∼13% and ∼17%, respectively, despite similar relationships between Tb and Ta, maximum ratio of evaporative heat loss to metabolic heat production and heat tolerance limits (∼50°C). These sex-specific differences in hornbill thermoregulation support the hypothesis that avian thermal physiology can vary within species in response to fine-scale microclimatic factors. In addition, Q10 for RMR varied substantially, with Q10 ≤2 in some individuals, supporting recent arguments that active metabolic suppression may be an underappreciated aspect of endotherm thermoregulation in the heat.

Характеристика видимых миграций птиц в дельте Днестра в 1974 -1976 гг.

The article deals with the results of observations of diurnal bird migrations and counts on a fixed route in the spring and autumn of 1974-1976, in the Dniester Delta. The total number of observation days was 82 (32 in spring and 50 in autumn, respectively). For this period, during observations and counts on the route, 135 bird species from 11 orders were registered, the total number of which exceeded 600 000 individuals. The study of migrations was carried out according to the E. Kumari method (1955). At the observation site, 80 species were counted, including 52 in spring and 60 in autumn. The Jaccard similarity coefficient (Jaccard index) was quite low between seasons and amounted to only 0.59. The frequency of occurrence of the majority of registered species was low. This may have been due to the area of the floodplains themselves, as well as to the weak extent of their anthropogenic transformation observed in the late 70s of the 20th century, which contributed to the bird migrations over the Delta in a wide front. The density of the spring migration flow was maximum in March and averaged 1077.4 ind. (n=32) per a daylight, while the autumn migration flow was 1926.2 ind. (n=50). There were interannual differences in the density of migrations in March. In the spring of 1975, the flight density was 900.3 ind. (n=15), and in 1976 it was almost twice more and amounted to 2094.7 ind. (n=11). There were no interannual differences in the intensity of autumn migrations. The maximum migration density was 2585.2 ind. (n=23) in October. The majority of non-passerine bird species flew in the morning: in spring up to 43.8%, in autumn - 64.1%. The diurnal activity of Passeriformes varied by season: in spring, morning migrations prevailed (56.1%), and in autumn, with the same ratio in the evening (56.1%). The vast majority of flocks (87 - 90%) amounted from 1 to 50 individuals. At altitudes up to 50 m, 37.0% flew, 51-150 m – 24.9% and above 150 m – 38.1% of birds. For a number of species, it was proved that the height of their flights in the general for the season migration sector of directions was higher than in the reverse directions.127 bird species were registered on all routes, of which 106 were registered on a permanent (fixed) route. Maximum species diversity was observed in March – 85, in April − 65, in September − 60, in October − 61 and in November – 40 species. The dynamics of the species composition of birds on a fixed route can be used as an additional characteristic of day transit migrations.

Hissing of geese: caller identity encoded in a non-vocal acoustic signal.

Non-vocal, or unvoiced, signals surprisingly have received very little attention until recently especially when compared to other acoustic signals. Some sounds made by terrestrial vertebrates are produced not only by the larynx but also by the syrinx. Furthermore, some birds are known to produce several types of non-syrinx sounds. Besides mechanical sounds produced by feathers, bills and/or wings, sounds can be also produced by constriction, anywhere along the pathway from the lungs to the lips or nostrils (in mammals), or to the bill (in birds), resulting in turbulent, aerodynamic sounds. These noises often emulate whispering, snorting or hissing. Even though hissing sounds have been studied in mammals and reptiles, only a few studies have analyzed hissing sounds in birds. Presently, only the hissing of small, nesting passerines as a defense against their respective predators have been studied. We studied hissing in domestic goose. This bird represents a ground nesting non-passerine bird which frequently produces hissing out of the nest in comparison to passerines producing hissing during nesting in holes e.g., parids. Compared to vocally produced alarm calls, almost nothing is known about how non-vocal hissing sounds potentially encode information about a caller’s identity. Therefore, we aimed to test whether non-vocal air expirations can encode an individual’s identity similar to those sounds generated by the syrinx or the larynx. We analyzed 217 hissing sounds from 22 individual geese. We calculated the Potential for Individual Coding (PIC) comparing the coefficient of variation both within and among individuals. In addition, we conducted a series of 15 a stepwise discriminant function analysis (DFA) models. All 16 acoustic variables showed a higher coefficient of variation among individuals. Twelve DFA models revealed 51.2–54.4% classification result (cross-validated output) and all 15 models showed 60.8–68.2% classification output based on conventional DFA in comparison to a 4.5% success rate when classification by chance. This indicates the stability of the DFA results even when using different combinations of variables. Our findings showed that an individual’s identity could be encoded with respect to the energy distribution at the beginning of a signal and the lowest frequencies. Body weight did not influence an individual’s sound expression. Recognition of hissing mates in dangerous situations could increase the probability of their surviving via a more efficient anti-predator response.

Quantitative Interspecific Approach to the Stylosphere: Patterns of Bacteria and Fungi Abundance on Passerine Bird Feathers

Feathers are the habitat of a myriad of organisms, from fungi and bacteria to lice and mites. Although most studies focus on specific taxa and their interaction with the bird host, anecdotal data glimpse feathers as holders of a system with its own ecology, what we call here the stylosphere. A major gap in our knowledge of the stylosphere is the ecology of the total abundance of microorganisms, being also rare to find studies that analyze abundance of more than one group of microorganisms at the bird interspecific level. Here, we quantified bacterial and fungi abundances through qPCR on the wing feathers of 144 birds from 24 passerine and one non-passerine bird species from three localities in Southern Spain. Bacteria and fungi abundances spanned three orders of magnitude among individual birds, but were consistent when comparing the right and the left wing feathers of individuals. Sampling locality explained ca. 14% of the variation in both bacteria and fungi abundances. Even when statistically controlling for sampling locality, microbial abundances consistently differed between birds from different species, but these differences were not explained by bird phylogeny. Finally, bird individuals and species having more bacteria also tended to held larger abundances of fungi. Our results suggest a quite complex explanation for stylosphere microorganisms' abundance, being shaped by bird individual and species traits, as well as environmental factors, and likely bacteria-fungi interactions.

Vocal Response to Traffic Noise in a Non-Passerine Bird: The Little Bustard Tetrax tetrax

Anthropogenic noise is spreading worldwide and can interfere with the acoustic communication of multiple animal groups. Species communicating in low-frequency ranges (having large sound production structures) and with limited vocal learning are expected to be especially vulnerable to human noise-induced masking interference. Yet how such species may confront this emerging impact has scarcely been explored. Here we examined the effect of anthropogenic noise on the calling behaviour of a sizeable non-passerine bird, the Little Bustard Tetrax tetrax, across a gradient of road traffic noise and in relation to male position within the lek. Using directional recordings and noise mapping, we determined inter– and intra-individual variation in call parameters and their relationship with noise level and frequency at both spatial and temporal scales, defined respectively as (i) variation of noise according to the position of the calling sites of each male within the lek (spatial scale) and (ii) fine temporal variation of noise experienced by individual males immediately prior to each call (temporal scale). Little Bustard males increased their call rate at sites exposed to higher average noise levels and at those located further from the nearest neighbour within the lek, whereas temporal changes in noise showed no effect on call rate. In contrast, call duration decreased with relative increases in noise level prior to each call, being unaffected by spatial changes in noise. Peak call frequency showed no significant variation over time and among sites. Our findings reveal that, despite its supposedly limited vocal learning, this species seems to exhibit fine-scale vocal adjustment, which implies some capacity to cope with anthropogenic noise. However, the lack of frequency shift suggests behavioural constraints that may compromise communication as the species uses low-pitched calls. This study provides insights into how some non-passerine birds may adjust their vocal sexual display to anthropogenic noise.—Barrero, A., Llusia, D., Traba, J., Iglesias-Merchan, C. & Morales, M.B. (2021). Vocal response to traffic noise in a non-passerine bird: the Little Bustard Tetrax tetrax. Ardeola, 68: 143-162.

Biomass, abundances, and abundance and geographical range size relationship of birds along a rainforest elevational gradient in Papua New Guinea.

The usually positive inter-specific relationship between geographical range size and the abundance of local bird populations comes with exceptions. On continents, the majority of these exceptions have been described from tropical montane areas in Africa, where geographically-restricted bird species are unusually abundant. We asked how the local abundances of passerine and non-passerine bird species along an elevational gradient on Mt. Wilhelm, Papua New Guinea relate to their geographical range size. We collected data on bird assemblages at eight elevations (200–3,700 m, at 500 m elevational increments). We used a standardized point-counts at 16 points at each elevational study site. We partitioned the birds into feeding guilds, and we obtained data on geographical range sizes from the Bird-Life International data zone. We observed a positive relationship between abundance and geographical range size in the lowlands. This trend changed to a negative one towards higher elevations. The total abundances of the assemblage showed a hump-shaped pattern along the elevational gradient, with passerine birds, namely passerine insectivores, driving the observed pattern. In contrast to abundances, the mean biomass of the bird assemblages decreased with increasing elevation. Our results show that montane bird species maintain dense populations which compensate for the decreased available area near the top of the mountain.

Vocal and non-vocal behavior interact differently in territorial strategies of two sympatric Rallidae species

Territorial interactions between animals involve correlated signaling and direct actions, yet different species vary in how they utilize each component. In theory, opponents should balance costs and benefits of territorial interactions, and restrict their conflicts to signaling when physical interactions are likely to escalate to serious injuries. We tested these predictions by simulating territorial intrusions in two sympatric non-passerine bird species: the Water Rail (Rallus aquaticus) and Little Crake (Zapornia parva). These species differ physically and behaviorally, with the former being larger and more aggressive, and known to cause serious or fatal injury to other birds. We measured vocal signals and approach behavior of each species towards conspecific and heterospecific playbacks (Little Grebe Tachybaptus ruficollis). Both species increased their calling rate in response to their conspecific treatments; however, Water Rails produced louder call variants, decreased the fundamental frequency of their calls, and produced more duets. In contrast, Little Crakes did not modify the acoustic structure of their calls and rarely participated in duetting. In addition to differences in vocal behavior, Water Rails approached the speaker exceptionally, whereas Little Crakes did it regularly. We conclude that while settling territorial conflicts, Water Rails utilized a purely signaling strategy involving reliable vocal signals and thus the avoidance of direct actions, whereas Little Crakes relied primarily on direct actions.

Relaxation of selective constraints shapes variation of toll-like receptors in a colonial waterbird, the black-headed gull

Nonspecific innate immune response is activated by toll-like receptors (TLRs), which recognize conserved molecular motifs characteristic for a broad spectrum of pathogens. In this study, we examined nucleotide substitution patterns and allelic diversity at five TLR genes in a wild nonpasserine bird, the black-headed gull Chroicocephalus ridibundus. We hypothesized that balancing selection can maintain high allelic diversity of TLR genes in the black-headed gull because of its ecological characteristics, coloniality, and migratoriness, which are associated with increased exposure and transmission of pathogens. Although we found moderately high levels of sequence polymorphism (8–49 haplotypes retrieved per locus within a sample of 60 individuals), most of these haplotypes were recorded at low frequencies within our study population. At the same time, we found no convincing evidence for the role of balancing selection in the maintenance of this variation (Tajima’s D < 0.5), and sites with a significant excess of nonsynonymous mutations (dN/dS > 1) were recorded only at two loci (TLR5 and TLR7). This pattern is consistent with relaxation of selective constraints, where most mutations are slightly deleterious and usually removed by purifying selection. No differences in the diversity and nucleotide substitution rates were found between endosomal loci responsible for viral RNA sensing and loci responsible for the recognition of extracellular pathogens. Our study provides the first information on evolutionary mechanisms shaping polymorphism of TLRs in a species from Lari suborder (gulls and allies) and suggests that TLR genes may be poorly responsive to ecological and life-history characteristics of hosts.

Prehistoric avifaunas from the Kingdom of Tonga

AbstractAvifaunas derived from Lapita archaeological sites excavated between 2004 and 2014 from four sites in the Vava'u Group and two on Tongatapu, Kingdom of Tonga are described, revealing birds encountered by the first human arrivals. A total of 741 identifiable bones revealed 24 avian taxa, among which terrestrial birds, especially rails, pigeons and parrots, were the most abundant. At a minimum, eight taxa, or 50% of the original non-passerine land bird diversity in the sample, are globally extinct. These include two megapodes (Megapodius alimentum and a larger unnamed megapode), three pigeons (a large Caloenas sp. indet., Didunculus placopedetes and Ducula shutleri sp. nov.), two rails (Hypotaenidia vavauensis sp. nov. and an unnamed one) and the parrot Eclectus infectus. The rail H. vavauensis was restricted to Vava'u and was flightless, with reduced wings, and larger than Hypotaenidia woodfordi of the Solomons, the largest congener hitherto found in the Pacific. The pigeon Du. shutleri was volant, but was the largest species in its genus and was widespread in the Kingdom. The evolution of Tongan avifaunas is related to varying ages (Pliocene to Pleistocene) of the island groups, where geological youth apparently precluded true giantism in the fauna.

Phylogeography of the blue-winged kookaburra Dacelo leachii across tropical northern Australia and New Guinea

ABSTRACTPhylogeographic studies of northern Australian birds frequently detect the influence of the Carpentarian Barrier in vicariantly structuring present-day genetic variation. Several barriers further west (e.g. Canning Barrier), and, where data are available, the Arafura Sea and Torres Strait separating Australia and New Guinea have an overall lesser effect. Using sequence data from mitochondrial (mtDNA) and nuclear DNA, we tested whether the Blue-winged Kookaburra (Dacelo leachii), widespread in monsoonal northern Australia and southern New Guinea, shows evidence of vicariance by these barriers. Viewed in phylogenetic context of other Australo-Papuan kookaburras (D. novaeguineae, D. gaudichaud, D. tyro), clear phylogeographic subdivisions were absent within the range of D. leachii. Subspecies groupings explained a significant amount of molecular variance within D. leachii, the most distinct being New Guinean D. l. intermedia. Genealogical relationships among mtDNA haplotypes suggest a recent connection between New Guinea and Western Australia, a history recently proposed for at least one other bird species of similar open woodland habitat. Species distribution modelling similarly indicated that climatic conditions during the last glacial maximum (LGM) may have facilitated a connection between New Guinea and present-day Western Australia along the exposed Arafura shelf, and that suitable conditions remained continuous across the Carpentarian Barrier during the LGM. This work adds to a growing body of data on population genetic structuring of Australia’s birds in relation to biogeographic barriers and it is the first such analysis of a large-bodied, non-passerine bird having an extensive geographic range in tropical and subtropical Australia and New Guinea.

Risk-based alarm calling in a nonpasserine bird

Recent studies have demonstrated the presence of risk-based variation in alarm calling in many vertebrate species. Most of the studies on birds, however, have focused on passerine systems perhaps due to the traditional view that passerine vocalizations are more complex. We investigated the presence of a risk-based alarm calling system in a nonpasserine, the herring gull, Larus argentatus, by recording birds presented with varying degrees of threat, and experimentally exposing and quantifying responses to manipulated alarm calls. We found that herring gulls communicate threat urgency in their alarm calls using both frequency and time parameters. Sound recordings indicated that herring gulls change centre frequency modulation patterns of their alarm calls, generate frequency discontinuities in notes and increase the rate of calling with increases in perceived threat level. Playback experiments showed that conspecifics pay attention to both frequency and time parameters and respond most urgently to playbacks of high-threat calls at a high call rate. A less urgent response to high-threat calls at a low call rate and to low-threat calls at a high call rate suggests that threat urgency information is reinforced by both call type and call rate in the herring gull system. This study is one of the first demonstrations of a risk-based alarm calling system in a nonpasserine.

An Annotated Checklist of Amblyceran Chewing Lice (Phthiraptera: Amblycera) from Wild Passerine Birds (Passeriformes) in South Africa

A total of 778 individuals of 150 bird species were examined: 123 (16 %) individuals of 40 non-passerine bird species belonging to 16 orders; and 655 (84 %) individuals of 110 passerine bird species (Passeriformes) belonging to 28 families. A total of 2041 chewing lice belonging to nine genera were found on passerine birds. Amblyceran lice were less frequent than ischnoceran lice (32.8 % vs 67.2 %, n = 2041). A total of 670 amblyceran lice (mean intensity = 5.0) were found on 133 passerine birds (20.3 %) of 43 species. The dominant amblyceran genus was Menacanthus with a dominance of 59.3 %, while the other two genera were less frequent: Myrsidea (36.9 %) and Ricinus (3.9 % ). A total of 50 amblyceran louse-host associations were recorded. An equal overall sex ratio as well as age ratio was found among the collected lice. An updated checklist of the species of amblyceran lice from passerine birds from South Africa is included and discussed. Two families, five genera and 32 species of lice are listed from 42 passerine bird hosts.

Low establishment success of alien non-passerine birds in a Central Italy wetland (Selva di Paliano: Latium)

The establishment success of exotic populations is typically analyzed as a binary response (success/failure), with the route taken by populations to their eventual outcome only rarely considered. This is especially true for wild populations, as well as for failed introductions. Therefore, we present a brief analysis of failed introductions of non-passerine bird species in a wetland of Central Italy. Only four species were able to reproduce independently from humans, but three of them went rapidly extinct because of poaching. The grey-headed swamphen Porphyrio p. poliocephalus, native to Western India and Pakistan, is the only species still present within the study area, despite the fact that it is in substantial decline. This high extinction rate may be due to (i) low propagule pressure, (ii) strict dependence on food supplied by man, (iii) poaching and (iv) lack of suitable nesting sites. Our study provides new evidence for the hypotheses that establishment success has been long overestimated, and that propagule pressure is a critical parameter in promoting the establishment of a non-native species in a new territory.

Extraordinary MHC class II B diversity in a non-passerine, wild bird: the Eurasian Coot Fulica atra (Aves: Rallidae).

The major histocompatibility complex (MHC) hosts the most polymorphic genes ever described in vertebrates. The MHC triggers the adaptive branch of the immune response, and its extraordinary variability is considered an evolutionary consequence of pathogen pressure. The last few years have witnessed the characterization of the MHC multigene family in a large diversity of bird species, unraveling important differences in its polymorphism, complexity, and evolution. Here, we characterize the first MHC class II B sequences isolated from a Rallidae species, the Eurasian Coot Fulica atra. A next-generation sequencing approach revealed up to 265 alleles that translated into 251 different amino acid sequences (β chain, exon 2) in 902 individuals. Bayesian inference identified up to 19 codons within the presumptive peptide-binding region showing pervasive evidence of positive, diversifying selection. Our analyses also detected a significant excess of high-frequency segregating sites (average Tajima's D = 2.36, P < 0.05), indicative of balancing selection. We found one to six different alleles per individual, consistent with the occurrence of at least three MHC class II B gene duplicates. However, the genotypes comprised of three alleles were by far the most abundant in the population investigated (49.4%), followed by those with two (29.6%) and four (17.5%) alleles. We suggest that these proportions are in agreement with the segregation of MHC haplotypes differing in gene copy number. The most widespread segregating haplotypes, according to our findings, would contain one single gene or two genes. The MHC class II of the Eurasian Coot is a valuable system to investigate the evolutionary implications of gene copy variation and extensive variability, the greatest ever found, to the best of our knowledge, in a wild population of a non-passerine bird.

Corncrake males learn new signal meanings during aggressive interactions

For many animals, the repertoires of songs or calls are relatively small and static during a lifetime. One reason for this is that there are different physiological limitations in the respiratory, phonatory and filter systems in different phylogenetic groups. Nevertheless, learning does not have to be associated exclusively with the acquisition of new vocalizations; individuals may recombine a limited number of elements already present in an individual's repertoire into new sequences. I tested the possibility of learning timing of calls in the corncrake, Crex crex , a nonpasserine bird with an extremely low repertoire of calls, using temporal patterns of calls during territorial interactions. I tested whether male are able to comprehend and use a new pattern by connecting known syntax with a new meaning through experience. Experiments with playback demonstrated that males were able to comprehend a new association between the temporal pattern and approaching behaviour of the intruder only after a few minutes of exposure to new circumstances. Additionally, apart from comprehending, males acquired a new signalling strategy; they began signalling their aggressive motivation using the new association. Because comprehension and usage of associations between the syntax of vocalizations and the approaching behaviour of males were modifiable as a result of experience, these results indicate that corncrakes' innate call structures and lack of complex and variable songs allow them to learn the temporal distribution of their calls. This suggests a much broader application and a vital role of contextual learning for the evolution of simple acoustic signalling systems.