Eurasian Capercaillie x Black Grouse

Eurasian Capercaillie x Black Grouse hybrid, Sweden?, 6th December 2008 - copyright Carl Gunnar Gustavsson

(photo ID: 1032)

This is one hybrid well enough known to have earnt itself its own name: Rackelhahn.

Carl Gunnar estimates the size of these males to be comparable to a female Capercaillie and describes the behaviour at lek as being rather similar to that of Capercaillie.  He notes the quality of sound as being more growling and lower frequency compared to Capercaillie.  Henry Lehto has also found their calls to be different, citing 8 individuals whose calls were very different from either parent - built from about six detached calls of growling with lower frequency. He notes that the tone could recall Carrion Crow Corvus corone or even Raven Corvus Corax.  A ninth bird apparently sounded more like a Capercaillie.

Carl Gunnar refers to a study (Höglund NH & Porkert J, 1989*) which finds that these birds should be crosses between a male Black Grouse and a female Capercaillie.  Crosses the other way round, male Capercaillie x female Black Grouse, were only possible by insemination (but look the same).  Male hybrids have poor sperm quality but still produced F2-hybrids in an enclosure with a female capercaillie.  Female hybrids exist but were considered sterile.

Apparently female hybrids inherit their colour pattern from the fathers.  Offspring of a male Black Grouse thus lack orangey-brown breast area and have tighter barring whereas the male Capercaillie x female Black Grouse offspring has the orangey-brown breast and broader barring resembling a Capercaillie hen.  The latter hybrid is however presumed not to occur in the wild.

* Experimetal crossing of capercaillie and Black Grouse: Zeitschrift für Jagdwissenschaft 35:221-234


The first Rackelhahn shown here was at a lek.

Eurasian Capercaillie x Black Grouse hybrid (same bird as in photo ID 1032 above), Sweden?, 6th December 2008 - copyright Carl Gunnar Gustavsson

(photo IDs: 1033-1034)

The next one was not at a lek.

Eurasian Capercaillie x Black Grouse hybrid, Sweden?, 6th December 2008 - copyright Carl Gunnar Gustavsson

(photo ID: 1035)

Henry Lehto has contributed that male Rackelhahns have elongated outer tail feathers and so a longer tail in flight compared to Capercaillies.  He thinks the Rackelhahn's body is narrower compared to Capercaillie (breast and body not so heavily built) and so this gives a different shape and enforces the impression of a "longer" tail.  A presumed female hybrid he once saw had the same impression.  The shape of this flying female did not fit female Capercallie.

This male is clearly shorter tailed than Black Grouse but in the flight shot you get a good view of the white wing-bar that's absent in Capercaillie.  Henry notes that these hybrids always show a lilac breast colour despite this being absent on the parent species.

Eurasian Capercaillie x Black Grouse hybrid, Kaskinen (Finland), 30th October 2010 - copyright Henry Lehto

(photo IDs: 2536-2540)

Finally here's one from a museum in Germany:

mounted Eurasian Capercaillie x Black Grouse hybrid (with female Capercaillied), Senckenberg Museum, Frankfurt, Hesse (Germany), March 2015 - copyright Joern Lehmhus

(photo IDs: 2314-2316)

Eurasian Capercaillie Tetrao urogallus
Black Grouse Tetrao tetrix