A shekara ta 1996, an kiyasta adadinsu ya kai kimanin 3900<unk>6350, daga cikin yawan jama'a na duniya kusan 10,000<unk>20,000. Hakanan shine wurin Cibiyar Kulawa da Bincike ta Epulu, a kan Kogin Epulu. Wannan kayan aikin ya samo asali ne daga 1928 lokacin da masanin kimiyyar ɗan adam na Amurka Patrick Putnam ya kafa sansanin a matsayin tashar kamawa, inda aka kama dabbobin daji kuma aka aika su zuwa gidajen namun daji na Amurka da na Turai. Har zuwa 2012 har yanzu yana aiki da wannan aikin, kodayake tare da wata hanyar daban, kamar yadda okapis ya kasance a Congo.
Patrick Putnam