The liger is a hybrid cross between a male lion (Panthera leo) and a tigress (Panthera tigris). Thus, it has parents with the same genus but of different species. It is distinct from the similar hybrid tiglon. It is the largest of all known extant felines.
Ligers enjoy swimming, which is a characteristic of tigers, and are very sociable like lions. Ligers exist only in captivity because the habitats of the parental species do not overlap in the wild. Historically, when the Asiatic Lion was prolific, the territories of lions and tigers did overlap and there are legends of ligers existing in the wild. Notably, ligers typically grow larger than either parent species, unlike tiglons which tend to be about as large as a female tiger.
The history of ligers dates to at least the early 19th century in India (Asia). In 1798, Étienne Geoffroy Saint-Hilaire (1772–1844) made a colour plate of the offspring of a lion and a tiger.
In 1825, G. B. Whittaker made an engraving of liger cubs born in 1824. The parents and their three liger offspring are also depicted with their trainer in a 19th century painting in the naïve style.
Two liger cubs born in 1837 were exhibited to King William IV and to his successor Queen Victoria. On 14 December 1900 and on 31 May 1901, Carl Hagenbeck wrote to zoologist James Cossar Ewart with details and photographs of ligers born at the Hagenbeck's Tierpark in Hamburg in 1897.
In Animal Life and the World of Nature (1902–1903), A.H. Bryden described Hagenbeck's "lion-tiger" hybrids:
It has remained for one of the most enterprising collectors and naturalists of our time, Mr. Carl Hagenbeck, not only to breed, but to bring successfully to a healthy maturity, specimens of this rare alliance between those two great and formidable felidae, the lion and tiger. The illustrations will indicate sufficiently how fortunate Mr. Hagenbeck has been in his efforts to produce these hybrids. The oldest and biggest of the animals shown is a hybrid born on the 11th May, 1897. This fine beast, now more than five years old, equals and even excels in his proportions a well-grown lion, measuring as he does from nose tip to tail 10 ft 2 inches in length, and standing only three inches less than 4 ft at the shoulder. A good big lion will weigh about 400 lb [...] the hybrid in question, weighing as it does no less than 467 lb, is certainly the superior of the most well-grown lions, whether wild-bred or born in a menagerie. This animal shows faint striping and mottling, and, in its characteristics, exhibits strong traces of both its parents. It has a somewhat lion-like head, and the tail is more like that of a lion than of a tiger. On the other hand, it has no trace of mane. It is a huge and very powerful beast.
In 1935, four ligers from two litters were reared in the Zoological Gardens of Bloemfontein, South Africa. Three of them, a male and two females, were still living in 1953. The male weighed 340 kg (750 lb) and stood a foot and a half (45 cm) taller than a full grown male lion at the shoulder.
Although ligers are more commonly found than tiglons today, in At Home In The Zoo (1961), Gerald Iles wrote "For the record I must say that I have never seen a liger, a hybrid obtained by crossing a lion with a tigress. They seem to be even rarer than tigons."
Size and growth
The liger is the largest known cat in the world. Imprinted genes may be a factor contributing to huge liger size. These are genes that may or may not be expressed on the parent they are inherited from, and that occasionally play a role in issues of hybrid growth. For example, in some dog breed crosses, genes that are expressed only when maternally-inherited cause the young to grow larger than is typical for either parent breed. This growth is not seen in the paternal breeds, as such genes are normally "counteracted" by genes inherited from the female of the appropriate breed.
Other big cat hybrids can reach similar sizes; the litigon, a rare hybrid of a male lion and a female tiglon, is roughly the same size as the liger, with a male named Cubanacan (at the Alipore Zoo in India) reaching 363 kg (800 lb). The extreme rarity of these second-generation hybrids may make it difficult to ascertain whether they are larger or smaller, on average, than the liger.
It is wrongly believed that ligers continue to grow throughout their lives due to hormonal issues. It may be that they simply grow far more during their growing years and take longer to reach their full adult size. Further growth in shoulder height and body length is not seen in ligers over 6 years old, same as both lions and tigers. Male ligers also have the same levels of testosterone on average as an adult male lion, yet are azoospermic in accordance with Haldane's rule. In addition, female ligers may also attain great size, weighing approximately 320 kg (705 lb) and reaching 3.05 m (10 ft) long on average, and are often fertile. In contrast, pumapards (hybrids between pumas and leopards) tend to exhibit dwarfism.
Hercules and Sinbad
Jungle Island, an interactive animal theme park in Miami, is home to a liger named Hercules, the largest non-obese liger, who is recognized by the Guinness Book of World Records as the largest living cat on Earth, weighing over 410 kg (904 lb). Hercules was featured on the Today Show, Good Morning America, Anderson Cooper 360, Inside Edition and in a Maxim article in 2005, when he was only 3 years old and already weighed 408.25 kg (900 lb). Hercules is completely healthy and is expected to live a long life. The cat's breeding is said to have been a complete accident. Sinbad, another liger, was shown on the National Geographic Channel. Sinbad was reported to have the exact weight of Hercules.
Shasta, a ligress (female liger) was born at the Hogle Zoo in Salt Lake City on 14 May 1948 and died in 1972 at age 24. The 1973 Guinness World Records reported an 18-year-old, 798 kg (1,759 lb) male liger living at Bloemfontein Zoological Gardens, South Africa in 1888 (this is not accurate as the zoo opened in 1920), (there are claims the liger was 756 lbs. and the year was actually 1953). Valley of the Kings animal sanctuary in Wisconsin had a male liger named Nook who weighed around 550 kg (1,213 lb), and died in 2007, at 21 years old. Hobbs, a male liger at the Sierra Safari Zoo in Reno, Nevada, lived to almost 15 years of age before succumbing to liver failure and weighed in at 410 kilograms (900 lb).
The fertility of hybrid big cat females is well documented across a number of different hybrids. This is in accordance with Haldane's rule: in hybrids of animals whose sex is determined by sex chromosomes, if one sex is absent, rare or sterile, it is the heterogametic sex (the one with two different sex chromosomes e.g. X and Y).
According to Wild Cats of the World (1975) by C. A. W. Guggisberg, ligers and tiglons were long thought to be sterile: in 1943, a fifteen-year-old hybrid between a lion and an 'Island' tiger was successfully mated with a lion at the Munich Hellabrunn Zoo. The female cub, though of delicate health, was raised to adulthood.
Ligers have a tiger-like striping pattern that is very faint and a lion-like tawny background. In addition they may inherit rosettes from the lion parent (lion cubs are rosetted and some adults retain faint markings). These markings may be black, dark brown or sandy. The background color may be correspondingly tawny, sandy or golden. In common with tigers, their underparts are pale. The actual pattern and color depends on which subspecies the parents were and on how the genes interact in the offspring.
White tigers have been crossed with lions to produce "white" (actually pale golden) ligers. In theory, white tigers could be crossed with white lions to produce white, very pale or even stripeless ligers. There are no black ligers. Very few melanistic tigers have ever been recorded, most being due to excessive markings (pseudo-melanism or abundism) rather than true melanism; no reports of black lions have ever been substantiated. As blue or Maltese Tigers probably no longer exist, gray or blue ligers are exceedingly improbable. It is not impossible for a liger to be white, but it is very rare.
Keeping the two species separate has always been standard procedure. However, ligers have occurred and do occur by accident in captivity. Several AZA zoos are reported to have ligers.
- "Liger cubs nursed by dog in China's Xixiakou Zoo". BBC News Asia-Pacific. 24 May 2011. http://www.bbc.co.uk/news/world-asia-pacific-13520472. Retrieved 25 May 2011.
- Bryden, A.H. (contributor). "Animal Life and the World of Nature" (1902–1903, bound partwork).
- Iles, G. At Home In The Zoo (1961).
- "Growth dysplasia in hybrid big cats". http://www.messybeast.com/genetics/growth-dysplasia.htm. Retrieved 23 June 2006.
- Howard Hughes Medical Institute (30 April 2000). "HHMI News: Gene Tug-of-War Leads to Distinct Species". http://www.hhmi.org/news/tilghman.html. Retrieved 23 June 2006.
- "Tigon". messybeast.com. http://www.messybeast.com/genetics/hyb-tigon.htm. Retrieved 21 July 2010.
- "Jungle Island: Mammals". http://www.jungleisland.com/about_mammals.php. Retrieved 5 November 2008.
- Guggisberg, C. A. W. "Wild Cats of the World." (1975).
- Peters, G. "Comparative Investigation of Vocalisation in Several Felids" published in German in Spixiana-Supplement, 1978; (1): 1–206.
- Courtney, N. The Tiger, Symbol of Freedom. Quartet Books, London, 1980.