From that wikipedia article on jayhawkers:
"When the University of Kansas fielded their first football team in 1890, the team was called the Jayhawkers.[28] Over time, the name was gradually supplanted by its shorter variant, and KU's sports teams are now almost exclusively known as the Jayhawks.
In the traditions promoted by KU, the jayhawk is said to be a combination of two birds, "the blue jay, a noisy, quarrelsome thing known to rob other nests, and the sparrow hawk, a stealthy hunter."[29]
Historic descriptions of the ornithological origin of the "jayhawker' term have varied. Writing on the troubles in Kansas Territory in 1859, one journalist stated the jayhawk was a hawk that preys on the jay.[30] One of the "Jayhawkers of '49" recalled that the name sprung from their observation of hawks gracefully sailing in the air until
"the audience of jays and other small but jealous and vicious birds sail in and jab him until he gets tired of show life and slides out of trouble in the lower earth."[5] In the Pat Devlin stories, the jayhawk is described more in terms of its behavior (bullying, robbing, and killing) than the type of bird it is.[31]"
