With widespread poaching throughout Borneo, Sumatran rhinos are running out of time and space. Worse, the fragmented, isolated populations that remain suffer from low rates of reproduction.
"Females do not find a mating partner within the small isolated populations any more," explained Petra Kretzschmar, scientist at the Leibniz Institute for Zoo and Wildlife Research (IZW). "The long non-reproductive periods lead to the development of reproductive tract tumors."
Scientists therefore urge that a combined effort of protective measures and breeding stimulation is needed to save the species from extinction. To do this they recommend relocating remnant populations of less than 15 individuals to highly protected areas, where conservationists can improve female fertility.
Until now, reasons behind the catastrophic decline of Sumatran rhinos have been rather obscure. While poachers have been known the kill rhinoceros for their valuable tusks, low reproduction among isolated females adds to a growing list of threats.
For the recent study, researchers specifically compared historical data with recent developments about the Borneo rhino (Dicerorhinus sumatrensis harrissoni). Today, only two subspecies of the Sumatran rhino exist: D. s. sumatrensis in Sumatra, Indonesia, and D. s. harrissoni, in Borneo in the states of Sabah, Malaysia, and Kalimantan, Indonesia.
While there are an estimated 100 individuals in Sumatra, Borneo rhinos are nearly extinct. In fact, one of the last Borneo rhinos was recently captured in the state of Kalimantan.
"The captured animal was one of the last females of its species," Kretzschmar added. "It died right after capture due to an infection of a snare wound."
Using mathematical models, researchers reconstructed the decline of the rhino population in the Tabin Wildlife Reserve (TWR) in Borneo. This, coupled with a recent study on preferred habitat use, helped researchers paint a clearer picture of Sumatran rhino history.
They conclude that monitoring reproductive health is vital to the species' long-term success. When females are relocated to protected areas, fertility (conception) should be optimized with the use of assisted reproduction techniques.
The recent study provides the data necessary to improve decisions regarding conservation management. Researchers believe their findings could be applied to other species of similar ecological standing.
Their study was recently published in the journal Global Ecology and Conservation.
