Conservation of the Red Kite Milvus milvus (Aves: Accipitriformes) Is Not Affected by the Establishment of a Broad Hybrid Zone with the Black Kite Milvus migrans migrans in Central Europe.

Among Accipitriformes sensu stricto, only a few species have been reported to form hybrid zones; these include the red kite Milvus milvus and black kite Milvus migrans migrans. M. milvus is endemic to the western Palearctic and has an estimated total population of 20-24,000 breeding pairs. The species was in decline until the 1970s due to persecution and has declined again since the 1990s due to ingestion of rodenticide-treated baits, illegal poisoning and changes in agricultural practices, particularly in its core range. Whereas F1 M. milvus × M. migr. migrans hybrid offspring have been found, F2 and F3 hybrids have only rarely been reported, with low nesting success rates of F1 hybrids and partial hybrid sterility likely playing a role. Here, we analyzed the mitochondrial (CO1 and CytB) and nuclear (Myc) DNA loci of 184 M. milvus, 124 M. migr. migrans and 3 F1 hybrid individuals collected across central Europe. In agreement with previous studies, we found low heterozygosity in M. milvus regardless of locus. We found that populations of both examined species were characterized by a high gene flow within populations, with all of the major haplotypes distributed across the entire examined area. Few haplotypes displayed statistically significant aggregation in one region over another. We did not find mitochondrial DNA of one species in individuals with the plumage of the other species, except in F1 hybrids, which agrees with Haldane´s Rule. It remains to be investigated by genomic methods whether occasional gene flow occurs through the paternal line, as the examined Myc gene displayed only marginal divergence between M. milvus and M. migr. migrans. The central European population of M. milvus is clearly subject to free intraspecific gene flow, which has direct implications when considering the origin of individuals in M. milvus re-introduction programs

First Year Dispersion of White-tailed Sea Eagles from Central Europe, Based on GPS/GSM Telemetry

Austria, Czech Republic and Hungary are located in central Europe, where the white-tailed sea eagle Haliaeetus albicilla (WTSEs) was one of the most frequent large raptor species during the 19th century, with substantial numbers of breeding pairs and wintering individuals. Due to landscape changes, direct persecution and intensified agriculture the population decreased dramatically in the 20th century. The species completely disappeared as a breeder from Czech Republic since at least 1920s until 1970s or even 1980s (Bělka, Horal, 2009) as well as from Austria since 1960s until the late 1990s (Probst, Peter, 2009; Probst, 2009). In Hungary, population of this once a widespread breeder (in 19th century) continually decreased until 1970s when a population minimum of ca 20 breeding pairs was reached, most of them in southern Danube valley (Bank et al., 2004). Later on, the breeding population began to recover slowly and now the breeding population consists from 35 territorial pairs (30 breeding) in Austria in 2017 (Probst, Pichler, 2017), 116 known breeding pairs in Czech Republic in 2016 (Bělka, 2017) and 279–307 breeding (egg-laying) pairs in Hungary in 2016 (Szelényi, 2016). It seems that WTSEs from Germany and Poland predominated in recolonization of the population in the western and northern part of the Czech Republic, and that the core Danube population was predominant in the recolonization of southeastern part of the Czech Republic and eastern Austria and Hungary. Moreover, ringing data and recent genetic studies suggest that WTSE populations in central Europe may even have been reestablished by eagles from North European populations (Literák et al., 2007, Nemesházi et al., 2016). Because there are only limited data about a dispersion of WTSEs from this recovered Central European population based on ringing data and because GPS/GSM telemetry is much more powerful tool for spatio-temporal studies than ringing activities, the aim of our study was to reveal the first year dispersion of WTE from central Europe using GPS/GSM telemetry

Sympatric wintering of Red Kites and Black Kites in south-east Europe

We characterized the spatiotemporal activities in winter grounds of the tagged Red Kites Milvus milvus originated from Austria, Czech Republic and Slovakia and wintering in south-east Europe. Birds arrived to winter grounds in Hungary, Croatia, and Greece from 10 July to 12 December (median 22 October) and departed from winter grounds between 14 February and 22 May (median 14 March), thus staying at winter grounds from 121 to 229 days (median 145, mean 161±43 SD). If we regarded kernel density estimate 80% (area of main foraging and roosting activities) as the best indicator as to the size of home range, we revealed that the size of a home range for Red Kites staying at one place through the entire winter was from 10 to 108 km2 (median 72, mean 60±36 SD) and that the size of home range for birds with local shift(s) in winter grounds was from 344 to 620 km2 (median 434, mean 466±115 SD). We found not only Red Kites at these places but often also Black Kites Milvus migrans. The numbers of Black Kites wintering together with Red Kites were higher than the number of Red Kites at all Greek winter grounds. At winter grounds in Hungary and Croatia, the number of Black Kites was lower than the number of Red Kites or Black Kites were wholly absent. Sympatric occurrences according to only direct observations of wintering Red and Black Kites were found also in some other locations in Bulgaria, Croatia, Greece and Hungary

Conservation of the Red Kite <i>Milvus milvus</i> (Aves: Accipitriformes) Is Not Affected by the Establishment of a Broad Hybrid Zone with the Black Kite <i>Milvus migrans migrans</i> in Central Europe

<div><p>Among Accipitriformes sensu stricto, only a few species have been reported to form hybrid zones; these include the red kite <i>Milvus milvus</i> and black kite <i>Milvus migrans migrans</i>. <i>M</i>. <i>milvus</i> is endemic to the western Palearctic and has an estimated total population of 20–24,000 breeding pairs. The species was in decline until the 1970s due to persecution and has declined again since the 1990s due to ingestion of rodenticide-treated baits, illegal poisoning and changes in agricultural practices, particularly in its core range. Whereas F1 <i>M</i>. <i>milvus</i> × <i>M</i>. <i>migr</i>. <i>migrans</i> hybrid offspring have been found, F2 and F3 hybrids have only rarely been reported, with low nesting success rates of F1 hybrids and partial hybrid sterility likely playing a role. Here, we analyzed the mitochondrial (<i>CO1</i> and <i>CytB</i>) and nuclear (<i>Myc</i>) DNA loci of 184 <i>M</i>. <i>milvus</i>, 124 <i>M</i>. <i>migr</i>. <i>migrans</i> and 3 F1 hybrid individuals collected across central Europe. In agreement with previous studies, we found low heterozygosity in <i>M</i>. <i>milvus</i> regardless of locus. We found that populations of both examined species were characterized by a high gene flow within populations, with all of the major haplotypes distributed across the entire examined area. Few haplotypes displayed statistically significant aggregation in one region over another. We did not find mitochondrial DNA of one species in individuals with the plumage of the other species, except in F1 hybrids, which agrees with Haldane´s Rule. It remains to be investigated by genomic methods whether occasional gene flow occurs through the paternal line, as the examined <i>Myc</i> gene displayed only marginal divergence between <i>M</i>. <i>milvus</i> and <i>M</i>. <i>migr</i>. <i>migrans</i>. The central European population of <i>M</i>. <i>milvus</i> is clearly subject to free intraspecific gene flow, which has direct implications when considering the origin of individuals in <i>M</i>. <i>milvus</i> re-introduction programs.</p></div

Review of past observations of hybrid <i>M</i>. <i>milvus</i> and <i>M</i>. <i>migr</i>. <i>migrans</i> individuals, and records of the nesting success of hybrid pairs and their offspring.

<p>The table was compiled based on [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159202#pone.0159202.ref010" target="_blank">10</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0159202#pone.0159202.ref029" target="_blank">29</a>].</p

Variable sites within the analyzed <i>CO1</i> haplotypes of <i>M</i>. <i>milvus</i> and <i>M</i>. <i>migr</i>. <i>migrans</i>.

<p>Variable sites within the analyzed <i>CO1</i> haplotypes of <i>M</i>. <i>milvus</i> and <i>M</i>. <i>migr</i>. <i>migrans</i>.</p

Nest sites of both <i>M</i>. <i>milvus</i> and <i>M</i>. <i>migr</i>. <i>migrans</i> co-localized with the distribution of forest patches.

<p>The nests of both species were localized to forest edges and to small forest fragments (including hedgerows and oak alleys at dams). Both avoided large forest complexes, and the nests of both species were frequently close to one another. The species occupied identical habitat across central Europe despite the landscape differing substantially between the agricultural lowlands of South Moravia <b>(A)</b>, heath and pond landscape of Saxonian Upper Lusitania <b>(B)</b> and hilly landscape of Thuryngia with many forest complexes and linear forest fragments <b>(C)</b>. Red dots denote <i>M</i>. <i>milvus</i> sampling nest sites, blue dots denote <i>M</i>. <i>migr</i>. <i>migrans</i> sampling nest sites, black dots show major cities, and green areas show the extent of forests.</p

Statistical parsimony network among <i>Milvus milvus</i> × <i>Milvus migrans migrans</i> complex <i>CytB</i> locus haplotypes (numbered) constructed in TCS 1.21.

<p>Country-specific observed frequencies of each haplotype are indicated within the circles. Lines indicate a single mutational step between haplotypes. Small black circles represent hypothesized unsampled or extinct haplotypes. Frames indicate species or subspecies identities.</p

Location of study sites and haplotypes, the distribution of which was not uniform across the sampled region.

<p>Each dot represents one or more nests sampled at the indicated coordinates (with a precision to the nearest 0.01°N and 0.01°E. Samples were collected in Germany (172 individuals, 89 families), Czech Republic (136 individuals, 56 families) and Slovakia (3 individuals, 1 family). <b>(A)</b> <i>M</i>. <i>milvus</i> of <i>CytB</i>-2 haplotype (red dots) and other haplotypes (black dots). <b>(B)</b> <i>M</i>. <i>migr</i>. <i>migrans</i> of the <i>CytB</i>-12 haplotype (red dots), <i>CO1</i>-11 haplotype (blue dots) and other haplotypes (black dots). <b>(C)</b> Sampling site of the hybrid <i>M</i>. <i>milvus</i> × <i>M</i>. <i>migr</i>. <i>migrans</i> offspring (red dot) and of <i>M</i>. <i>milvus</i> individuals with the mitochondrial haplotype <i>CO1</i>-1, <i>CytB</i>-2, which was identical to that of the hybrids (black dots). Abbreviations of countries are indicated.</p