Bighorner

Bighorners are mutated bighorn sheep found in the Mojave Desert around New Vegas.

Characteristics
Evolved from Bighorn Sheep, Bighorners are dedicated herbivores and are primarily found in wild herds of three to seven members in the Mojave Desert, or in domesticated drifts of varying size in settlements such as Goodsprings, Jacobstown, or around Cottonwood Cove. While settlers use them for their horns, meat, and fur, it has been observed that the alpha male, or Bull, can usually be found in close proximity to a Banana Yucca Fruit, making for effective VATS herb tracking. They are generally laid-back beasts with surprisingly docile dispositions, in spite of being quite capable of being extremely dangerous when provoked. According to Easy Pete, Bighorners can't be used as pack animals.

Combat
In combat situations, Bighorners are unique in that they are rarely outright hostile. Unprovoked Bighorners will not actively pursue the Courier like other monsters, and, if left alone, are content to graze and mind their own business. Getting too close to wild Bighorners agitates them; they will growl and snort if someone gets too close, and will turn hostile if the offender doesn't back away from them fast enough. Bighorners with young, however, become enraged if their young are approached, and will fight to the death with very little provocation in order to protect their offspring.

Bighorners can't take a huge amount of abuse (they are squarely on par with a Radscorpion in terms of health), but their head-butting attacks are absolutely devastating, capable of sending enemies flying backwards or knocking them down. Throw in the fact that Bighorners can inflict heavy damage and run very fast, and they can make an intimidating foe for the unprepared.

A critical head shot is a killing blow against a Bighorner, and such a 'sneak critical' is easily achieved with a scoped Varmint Rifle. Note that hitting their horns will count as a headshot.

Bugs

 * Bighorners can commonly be found in a glitch where they are bouncing up and down rapidly on the spot, this could be due to bighorners spawning on each other.
 * Their knockdown attack can affect the player even when the bighorner is at a considerable distance. Observed with the animal being approximately another bighorner away. This could be caused by the player standing atop rocks or other irregular terrain.
 * Some may appear in the NCRCF near the entrance, when attacked the powder gangers will attack them but most of the Bighorners are Bulls and may kill all the powder gangers.