Walter Rothschild's unusual birds

Hybrid grouse

Hybrid between a black grouse, Lyurus tetri, and a willow grouse, Lagopus lagopus.

Famous for his vast collection of natural history specimens at Tring, Lord Lionel Walter, Baron Rothschild (1868-1937) amassed about 300,000 bird skins and mounts.

3,500                          2,500

skin specimens                mounted specimens


Baron Rothschild is famous for his passion for ornithology. Rothchild's interest in bird hybrids, colour aberrations and the phenomenon of ‘sex reversal’ is less well known. He collected an impressive number of examples of these unusual birds.

Before he died Rothschild sold almost his entire bird skin collection to the American Museum of Natural History in New York in the early 1930s. He kept back about 3,500 skin specimens, as well as his 2,500 or so mounted specimens on display in his public museum.  

When Rothschild died in 1937, his remaining research collections and his public museum passed to the Natural History Museum. Most of the abnormally-coloured specimens and hybrids in his bird collection were mounted, and are still present in the collection today.

Cross breeds

Good examples of both hybridisation and colour aberrations are found among the game birds (of the order Galliformes, including grouse, pheasant and partridges). Rothschild had many rare hybrid specimens, including

  • hybrids between species within the same family,for example:
    • black grouse (Lyurus tetrix) crossed with willow grouse (Lagopus lagopus)
    • common pheasant (Phasianus colchicus) crossed with domesticated chicken (Gallus gallus
  • hybrids between species from different families, for example:
    • black grouse crossed with common pheasant
    • guinea fowl (Numida meleagris) crossed with Indian peafowl (Pavo cristatus). 

Although Rothschild keenly acquired hybrid specimens for his collection he never published on the subject.

Black grouse and ptarmigan hybrid

Hybrid between a black grouse, Lyurus tetri, and a willow grouse, Lagopus lagopus.

Switching sexes

The phenomenon called ‘sex reversal’, when females birds assume male plumage, is also well-illustrated in game birds. 

Normally in female birds only the left ovary, or gonad, fully develops, leaving the tissue of the undeveloped right gonad almost dormant. 

If the developed left ovary stops being active or is damaged, eg due to age, illness or injury, the right gonad then develops along testis-like lines and produces a male-like hormone, resulting in the bird showing male plumage and even male behaviour.

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