Kathmandu, Nov. 29 -- Despite Nepal achieving zero rhino poaching for the past five years, conservationists say the country should not let its guard down given the official extinction of the Sumatran rhinoceros in Malaysia last week.

There has been a rise in rhino deaths in Nepal recent years, for various reasons such as natural death, overcrowding in protected areas and human-animal conflict due to habitat encroachment. But the biggest threat to rhino conservation in the post-poaching era is the growing infrastructure that crisscrosses nature reserves.

Conservationists interviewed for this article said sustaining rhino numbers will be even more challenging because the animal's floodplain habitat is affected by upstream infrastructure d...