Investigations into the relative abundance of Intersexual pigs (Sus sp.) in the Republic of Vanuatu.
James K. McIntyre Zoologist
Southwest Pacific Research Foundation
1009 White Street
Fernandina Beach, Florida 32034 USA
Phone/Fax (904) 261-5630
This article was originally published in "Science in New Guinea" vol. 22(3); 1997
The existence and great abundance of a unique form of pig intersexuality was verified on the northernmost islands of Vanuatu.
Morphological examinations were conducted on 54 pigs from the islands of Malo, Ambae, and Aore. Through blood analysis, estradiol and testosterone levels were derived. Subsequent comparisons of the estradiol/testosterone ratio yielded results consistent with "maleness". Fifty-one dental and mandibular measurements of the Vanuatu Sus. sp. specimens plotted within the feral swine target group.
Behaviorally, the Vanuatu intersex pig exhibits periods of aggressiveness that generally coincide with a sow in heat. When encountered in the "bush", the naravé (local name for the intersexual pig) is a stronger and more aggressive adversary than the "normal" native wild pig. Six gross dissections yielded totally male internal sex organs. Four separate graduations or phases of the intersexual condition are described according to their external genitalia. The phases of intersexuality appeared to be an inherited trait. Certain sows (called falé-ravé) are known intersex producers and 20% of their offspring will be intersexual.