Stallion’s attack on newborn foal witnessed by researcher

A stallion near Reno was observed attacking a foal in his herd
Horses in the Sand Wash Basin Wild Horse Herd Management Area in northwestern Colorado. A stallion near Reno was observed attacking a foal in his herd. © BLM

A researcher observing a herd of wild horses in Nevada has described an infanticide attempt by a stallion on a foal estimated to be less than an hour old.

She also saw the spirited and successful defence put up by the mare, which saved her foal.

Meeghan Gray, from the University of Nevada, in Reno, was observing the herd as part of another study when the stallion’s attack unfolded.

Gray, in an article to be published in the journal Biology Letters, said while infanticidal attacks have been documented in several equid species in captivity, it has never been witnessed in free-roaming feral horses.

Gray said a feral horse population in the Virginia Mountain Range outside Reno, Nevada, was observed intensively from 2004 to 2008.

The total population fluctuated from more than 1200 horses down to 1000 horses over the course of those years.

The study included about 300 known horses. The band in which the attack occurred was seen on a weekly basis to determine band membership and fidelity.

At the time of the attack, the band consisted of two adult stallions, two adult mares, a juvenile male and one male foal.

During routine observations on April 12, 2005, the attack was witnessed.

At 4.14pm Gray noted that a mare in the group had recently given birth. A new female foal was covered with mucous and lying on the ground next to her dam.

The foal appeared to be no more than an hour old when the attack occurred and had not attempted to stand up.

The rest of the band, including the dominant band stallion, were all resting near the mare and newborn foal. At 4.20pm, a stallion (stallion B) from a nearby band called out and approached the mare.

She immediately gave a head threat towards stallion B. The foal tried unsuccessfully to stand up.

The band stallion (stallion A) then lunged towards the mare and foal and immediately bit the foal on the neck several times. It picked the foal up by the shoulders twice and shook it around several times. The foal was dropped to the ground and subsequently bitten and kicked by the front legs of the stallion several times, Gray said.

The attack lasted about a minute, during which the mare defended her foal by charging, biting and kicking the stallion, which led to the end of the attack, she said.

After the attack, the stallion that launched the attack had several aggressive interactions with the other stallions and continued to try to herd the mare away from the area.

The mare continued to charge and use head threats against the attacking stallion when he came near her and she remained in her position over the foal.

The mare successfully protected her foal from additional attacks.

“The foal survived the attack and later weaned successfully,” Gray wrote.

“The stallion recently took over the band and was excluded as the sire through genetic analysis.

“While this type of attack is rare, this case lends support to the sexual selection hypothesis and further demonstrates that equids have evolved with the risk of infanticide.

“Furthermore, it shows that maternal protectiveness can be successful against attacks by infanticidal males.”


An infanticide attempt by a free-roaming feral stallion (Equus caballus) Meeghan E. Gray, Program in Ecology, Evolution and Conservation Biology, University of Nevada, Reno, NV 89557, USA. DOI 10.1098/rsbl.2008.0571

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