The term berdache originates from the Arabic word bardaj (“slave” or “kept boy”). That word spread into western Europe, as a result of contact with the Muslim world, and became the Spanish term bardaxa/bardaje (person engaging in sodomy) and then the French term bardache (a boy kept by a pederast). While the Spanish and French originally used the term for male transvestites or the passive partner in sex between males, anthropologists later applied the term berdache to American Indians who assumed the dress, social status, and role of the opposite sex.      britannica.com

Citation
Callender, C., & Kochems, L. M. (1983). The North American berdache. Current Anthropology, 24(4), 443–470. https://doi.org/10.1086/203030
Abstract
Describes the berdache among North American Indians as a person, usually male, who was anatomically normal but assumed the dress, occupations, and behavior of the other sex to effect a change in gender status. This shift was not complete; rather, it was a movement toward a somewhat intermediate status that combined social attributes of males and females. The ritual roles of male berdaches rested on their definition as nonwomen. While it was not a status instituted for homosexuals, homosexuality was a reflex of assuming the status rather than a factor promoting its assumption. The authors' discussion focuses on issues of distribution, numbers, transvestism, occupations, warfare, sexuality, ontogeny, and social positions concerning the berdache. Comments by 15 authors are included, to which the present author responds by grouping the information and opinions into 3 topical categories: the berdache institution itself, methodology, and explanatory hypotheses. (French, Spanish & Russian abstracts) (231 ref) (PsycINFO Database Record (c) 2017 APA, all rights reserved)

Biologically male berdache were also themselves often sexually active with male tribal members, these interactions being considered something separate from normal homosexual encounters. This is because Native American sexual encounters were often split into procreative and non-procreative categories, as opposed to hetero/homosexual, and male encounters with berdache were simply seen as non-procreative (Roscoe 1998).