Green’s Dictionary of Slang

(US) an inhabitant of Nevada.

1863		Walla Walla Statesman 6 June 1/7: The inhabitants of Nevada are called Sage Hens [DA].
1871		Semi-Wkly Louisianan 31 Aug. 1/3: The Nicknames of the States [...] Nebraska, bug eaters; Nevada, sage hens; New Hampshire, granite boys; New Jersey, blues or clam catchers.
1888		Daily Alto (CA) 2 Apr. 6/1: Nevada, ‘Sage Hen State’.
1894		N.Y. Weekly Trib. 7 Mar. 4/3: Nevada [is] [...] called Sage Hen State [DA].
1909		J. Ware Passing Eng. of the Victorian Era 213/1: Sage hens (American). People of Nevada – probably from the multiplicity of prairie fowl which frequent the sage bushes which cover the prairie in that state.
1911		C.E. Mulford Bar-20 Days 102: You blasted sage-hen!
1924		C.E. Mulford Hopalong Cassidy Returns 294: Hello, Ben, you old sage-hen!
1946		C. McWilliams Southern Calif. Country 172: Nevadans are ‘sage hens’ [DA].