Western Palearctic black-and-white flycatchers
Encyclopedia
The term Western Palearctic black-and-white flycatchers is used to refer to a group of similar-looking bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s in the genus
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Ficedula:
  • Atlas Flycatcher
    Atlas Flycatcher
    Atlas Pied Flycatcher or Atlas Flycatcher is a bird in the an Old World flycatcher family, one of the four species of Western Palearctic black-and-white flycatchers; it is endemic as a breeding species to North-west Africa....

     F. speculigera which breeds in Northwest Africa
  • Collared Flycatcher
    Collared Flycatcher
    The Collared Flycatcher, Ficedula albicollis, is a small passerine bird in the Old World flycatcher family, one of the four species of Western Palearctic black-and-white flycatchers. It breeds in southeast Europe and southwest Asia and is migratory, wintering in sub Sahara Africa...

     F. albicollis which breeds in Eastern Europe
    Eastern Europe
    Eastern Europe is the eastern part of Europe. The term has widely disparate geopolitical, geographical, cultural and socioeconomic readings, which makes it highly context-dependent and even volatile, and there are "almost as many definitions of Eastern Europe as there are scholars of the region"...

  • European Pied Flycatcher
    European Pied Flycatcher
    The Pied Flycatcher, Ficedula hypoleuca, is a small passerine bird in the Old World flycatcher family, one of the four species of Western Palearctic black-and-white flycatchers. It breeds in most of Europe and western Asia. It is migratory, wintering mainly in western Africa. It hybridizes with...

     F. hypoleuca which breeds in Western Europe
    Western Europe
    Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...

  • Semi-collared Flycatcher
    Semi-collared Flycatcher
    The Semi-collared Flycatcher , Ficedula semitorquata, is a small passerine bird in the Old World flycatcher family, one of the four species of Western Palearctic black-and-white flycatchers. It breeds in the southeastern corner of Europe, the Middle East and southwestern Asia. It is migratory,...

     F. semitorquata of Southeast Europe
    Southeast Europe
    Southeast Europe or Southeastern Europe is a relatively recent political designation for the states of the Balkans. Writers such as Maria Todorova and Vesna Goldsworthy have suggested the use of the term Southeastern Europe to replace the word Balkans for the region, to minimize potential...

     and Southwest Asia
    Southwest Asia
    Western Asia, West Asia, Southwest Asia or Southwestern Asia are terms that describe the westernmost portion of Asia. The terms are partly coterminous with the Middle East, which describes a geographical position in relation to Western Europe rather than its location within Asia...



European Pied and Collared Flycatchers hybridise to a limited extent where their ranges meet; the hybrids have reduced fitness
Fitness (biology)
Fitness is a central idea in evolutionary theory. It can be defined either with respect to a genotype or to a phenotype in a given environment...

 and usually do not survive their first winter (Parkin 2003). Female hybrids are usually sterile
Infertility
Infertility primarily refers to the biological inability of a person to contribute to conception. Infertility may also refer to the state of a woman who is unable to carry a pregnancy to full term...

 (Gelter et al. 1992; see also Haldane's Rule
Haldane's rule
Haldane's rule or Haldane's law was formulated in 1922 by the British evolutionary biologist J.B.S. Haldane. It describes hybrid sterility in species and is extended to describe speciation in evolutionary theory, in two parts: the rule of hybrid sterility and the rule of hybrid inviability...

).

All species leave their breeding grounds to winter in Sub-Saharan Africa
Sub-Saharan Africa
Sub-Saharan Africa as a geographical term refers to the area of the African continent which lies south of the Sahara. A political definition of Sub-Saharan Africa, instead, covers all African countries which are fully or partially located south of the Sahara...

.

Identification of these birds, especially in female and immature plumages is considered difficult, and several identification papers have been published on the subject.
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