Hybrid (biology) are the mule, a cross between a female horse and a male donkey, and the hinny, a cross between a female donkey and a male horse. Pairs of complementary types like the mule and hinny are called reciprocal hybrids. Among many other mammal crosses are hybrid camels, crosses between a bactrian camel and a dromedary. The first known instance of hybrid speciation in marine mammals was discovered in 2014. The clymene dolphin ("Stenella clymene") is a hybrid of two Atlantic species, the spinner and striped dolphins. Cagebird breeders sometimes breed bird hybrids known as mules between species of finch, such
Mule the foal was indeed her offspring. A 1939 article in the "Journal of Heredity" describes two offspring of a fertile mare mule named "Old Bec", which was owned at the time by the A&M College of Texas (now Texas A&M University) in the late 1920s. One of the foals was a female, sired by a jack. Unlike its mother, it was sterile. The other, sired by a five-gaited Saddlebred stallion, exhibited no characteristics of any donkey. That horse, a stallion, was bred to several mares, which gave birth to live foals that showed no characteristics of the donkey. In the