11/11/2026
On April 12, 2005, a feral mare turned on the lead stallion of her own harem, driving him back with her teeth and hooves. Her daughter was less than an hour old and still unable to stand when the band’s dominant male grabbed the newborn by the shoulders.
That afternoon in the Virginia Range outside Reno, Nevada, University of Nevada researcher Meeghan E. Gray passed a band of free-roaming feral horses at 3:40 p.m. and saw no new foals. When she passed the group again at 4:14 p.m., one of the mares had just given birth.
The newborn filly lay on the ground beside her mother, still coated in birth mucus and not yet steady enough to try standing. Around them, the rest of the harem and the band’s dominant stallion rested quietly.
Six minutes later, at 4:20 p.m., a second stallion from a nearby band called out and walked toward the mother and her foal. The mare immediately gave a head threat toward the outsider as her filly tried and failed to get to her feet.
Then the danger came from inside her own group.
Instead of merely intercepting the rival male, the mare’s own lead stallion lunged at the mother and newborn. He bit the filly on the neck several times, picked her up by the shoulders twice, shook her, dropped her to the dirt, and bit and kicked her with his front legs.
In feral horse society, the dominant band stallion normally holds unchallenged rank over his mares. This mother did not submit to him.
The mare charged straight into her lead stallion, biting and kicking him until he broke off the attack. She positioned herself directly over her daughter on the ground. Over the minutes that followed, the resident stallion clashed with the neighboring stallion and repeatedly tried to herd the mare away from the birth site.
She refused to leave her filly behind. Standing over the newborn, the mare continued to charge and give head threats toward her lead stallion every time he came near, forcing the dominant male of her own band to give ground.
At 5:39 p.m., just over an hour after the attack, the shaken filly stood up on her own legs for the first time. Eight minutes later, at 5:47 p.m., she nursed from the mother that had just fought for her life.
Gray tracked the band over the next year as the filly healed from her superficial scrapes and grew beside her dam. Later microsatellite DNA testing helped explain why the resident male had turned on a newborn inside his own harem. The stallion had recently taken over the band, and genetic analysis excluded him as the filly’s sire.
While DNA established that he was not the father, his motive remains an inference grounded in evolutionary biology. Under the sexual selection hypothesis, an incoming male that kills an unrelated infant can shorten the mother’s nursing period and bring her back into breeding condition sooner to carry his own offspring. Infanticide had been recorded among captive equids, including domestic horses and Przewalski’s horses, but Gray’s report in Biology Letters marked the first documented infanticide attempt in free-roaming feral horses.
It also proved what maternal defense can do against a dominant male. Because the mare held her ground over a newborn that could not yet stand, the filly survived her first afternoon in the Nevada hills and was successfully weaned the following year.
Image is for illustration purposes only
Source: Gray, M. E. (2009), "An infanticide attempt by a free-roaming feral stallion (Equus caballus)," Biology Letters 5(1): 23-25, DOI: 10.1098/rsbl.2008.0571
