Wilbur-Cruce Horses

A Genetic Time Capsule

In 1989, a rare and genetically important group of horses leapt into the public spotlight when the Wilbur-Cruce ranch on which they had lived for over 100 years became part of the Buenos Aires National Wildlife Refuge in southern Arizona.

Descended from a herd of 26 horses purchased by Dr. Ruben Wilbur in the late 1800’s from Rancho Dolores in Sonora, Mexico, their origins dated back the 14 and 1500’s during the period of Spanish exploration. Jesuit priest and missionary Father Eusebio Francisco Kino (1665-1711) bred and managed some of the largest numbers of Spanish livestock, including horses and cattle.

The Beginning

The story of the Wilbur-Cruce ranch and the horses who were integral to its survival was documented in A Beautiful, Cruel Country written by Dr. Wilbur’s granddaughter, Eva Antonia Wilber-Cruce, who’d been managing the ranch since her father’s death in 1933. Upon the sale of a large portion of the ranch to The Nature Conservancy in 1989, the 86-year-old Wilbur-Cruce donated the herd to the American Minor Breeds Conservancy, (now American Livestock Conservancy) with strict instructions that their rare Spanish bloodlines be protected and maintained.

Through the Conservancy, the unique history and heritage of the Wilbur-Cruce herd came to the attention of several renowned equine geneticists who immediately identified the horses’ characteristics as Old World Spanish, a genetic type thought long gone.

Genetic Evaluation

“The Cruce horses are one of a very small handful of strains of horses derived from Spanish colonial days that persist as purely (or as nearly as can be determined) Spanish to the present day. They are one of very few known ‘rancher’ strain of pure Spanish horses that persists in the southwest. The Cruce horses are of great interest because they are a nonferal strain . . . truly unique. The Cruce population is a most significant discovery of a type of horse thought to be gone forever.”

– Dr. D. Phillip Sponenberg, DVM, PhD, Associate Professor of Pathology and Genetics at the Virginia-Maryland Regional College of Veterinary Medicine and Technical Advisor for The Livestock Conservancy

Preserving the Herd

Dr. Sponenberg’s evaluations were based on phenotype as well as blood typing, supporting the oral and written histories maintained by the Wilbur-Cruce family. Concerned that this rare herd be preserved, the Conservancy contacted breeders with an interest in Spanish horses. Robin Collins, then President of the California Hooved Animal Humane Society and a noted horse trainer and animal behaviorist, was asked to participate. With Eva Wilbur-Cruce’s approval, Collins received a little over one-third of the 50 horses selected to start the W-C conservation program.

Since 1990, Collins has carefully managed a conservation breeding program in California for the Wilbur-Cruce horses at Rancho Del Sueno, the equine division of The Heritage Discovery Center, Inc. According to Dr. E. Gus Cothran, Director of the Equine Genetics Lab at Texas A & M University, “The WC (Wilbur-Cruce) horses have been maintained by Collins in a thoughtful and planned manner and this has allowed the preservation of almost all the genetic diversity that was present when the herd was recovered in 1989.”

    Their Significance

    The importance of these findings cannot be overstated. According to Dr. Sponenberg, interest in rare breed conservation in horses “is limited to those breeds uninfluenced by the modern Arabian and the Thoroughbred.” This is due to the “incredible scarcity of such populations worldwide. The Cruce horses fit in this category very securely, and are therefore of great interest and importance not only in North America, but also in the worldwide efforts to conserve genetically unique populations of livestock.”

    The Wilbur-Cruce horses are important from a historical aspect as well. They represent the horse that settled the Americas, both North and South. Embodied in this breed are the three main types/divisions of Iberian horses brought over from Spain:

    • Carthusian/Villano: Proto-Andalusian; used for war, mounted games, and racing

    • Jinete/Jennet: Elegant riding horse; smaller type with smooth gaits; frequently gaited

    • Gallego/Barb: Agile working horse; used for bullfighting and working cattle.

    Small herds influenced by Spanish blood did survive among Native American tribes, ranchers, and in the wild deserts and mountains of the western United States. But as time went on, even these dwindled to a few remaining unmixed groups, and rarely without the infusion of non-Iberian blood.  The Wilbur-Cruce Spanish Horse is one such group, and its isolation, confirmed by blood typing, DNA, and its phenotype, has preserved the most precious of its Spanish characteristics —intelligence, agility, and hardiness—along with the genetic biodiversity that classifies it as a critical resource in a world growing increasingly homogenous.