“Jayhawker” originated in Kansas, and according to some authorities, it came into use in the late 1840s. The name was inspired primarily by the predatory habits of the hawk, but it implied, too, the noisy, mischievous nature of the jay. The combination became the “jayhawk,” a bird unknown to ornithology. The name was widely accepted in Kansas by the late 1850s, when anti-slavery advocates intent on defending Kansas Territory against pro-slavery “border ruffians” from Missouri adopted it. Kansans liked the tough image it conveyed during those bloody days of pre-Civil War violence, and they continued to use it once the war began. Missourians applied the name to Kansans, too, but negatively. They thought it fit the destructive raiders who plundered and destroyed their property before and during the war.
This usage was so widely known by the time of the war that Arkansans called any Kansas troops who entered the state jayhawkers. That happened most often in northwest Arkansas, although several Kansas regiments also served prominently around Pine Bluff (Jefferson County) and in the Camden Expedition. However, so notorious did the destructive behavior of the Kansans become that Confederate Arkansans also used the name as an epithet for any marauder, robber, or thief. This included Union guerrillas from Missouri who raided communities in northern Arkansas. It even applied to rebel guerrillas. Confederates reacted to plundering by their own guerrilla chiefs by chastising them as “jayhawking captains” and decrying their “system of ‘jayhawking.’” A Confederate calvaryman, worried about the ill effect that depredations by rebel guerrillas was having upon public morale in northern Arkansas, declared in October 1862, “I have always opposed these little Jaw Hawker Parties, and now think if men who wanted to do any thing, the army is the place to act.” Indeed, “jayhawk” become a verb implying theft. Even Union soldiers spoke of “jayhawking” the property of Southern civilians….
The more brutal and senseless their deeds, the more likely men were to be called jayhawkers or bushwhackers. Bushwhacker received more universal usage, since guerrillas could be found everywhere fighting for the Union or the Confederacy. Jayhawkers would always be linked to Kansas, but so notorious had the violence perpetrated by early Kansas raiders become that the nature of the deed, rather than any geographical place, came to define the name. The slippery meanings of both names serve to underscore the bitterness and confusion of all civil wars.