Approximately 15% of all mammal species are categorized as Data Deficient on the IUCN Red List (Schipper et al., 2008, Science, 322, 225–230), a status that potentially hampers conservation planning, prioritization and action (Bland et al., 2015, Conservation Biology, 29, 250–259). The Annamite striped rabbit Nesolagus timminsi is a forest-dwelling lagomorph restricted to the Annamite mountain range on the border of Viet Nam and Lao. The species was discovered by science just over 20 years ago (Surridge et al., Nature, 1999, 400, 726) and, until recently, little was known about its ecology or population status. It was thus categorized as Data Deficient in 2002 and 2008 (Abramov et al., 2008, The IUCN Red List of Threatened Species: e.T41209A10412274) although, like all terrestrial mammals in the Annamites, this species has probably declined as a result of the snaring prevalent in the region (Gray et al., 2018, Biodiversity & Conservation, 27, 1031–1037).
Recent studies, in particular using camera trapping, have provided new insights into the status of the Annamite striped rabbit across much of its range. Although some studies in Viet Nam have detected the species, mostly at only a small per cent (≤ 5%) of camera-trap stations, others have failed to record it, despite considerable camera-trapping effort. Many of these studies have also failed to record other species known to be highly susceptible to snaring, suggesting these results are a consequence of snaring-driven declines rather than naturally low densities. Landscape-scale camera trapping across a protected area complex in central Viet Nam has recorded low Annamite striped rabbit occupancies, with most detections in the less accessible and better patrolled parts of the surveyed area (Tilker et al., 2018, Oryx, 54, 178–187). The species appears to be approaching local extinction in one protected area where snaring has probably been more intensive, providing further evidence for snaring-driven declines.
Together, this body of information indicates that Annamite striped rabbit populations have almost certainly declined by > 50% over the past 10 years and, given increasing levels of snaring, will probably decline by a similar rate over the next decade, triggering a categorization as Endangered based on criteria A2d + 3d + 4d (Tilker et al., 2019, The IUCN Red List of Threatened Species: e.T41209A45181925). Without effective conservation actions this species is in danger of extinction. In addition to underscoring the tenuous existence of the Annamite striped rabbit, the new categorization is a cautionary lesson highlighting the risk of silent extinction that many Data Deficient species face (Howard & Bickford, 2014, Diversity and Distributions, 20, 837–846).
What will it take to save the Annamite striped rabbit? As with most threatened Annamite mammals, the highest priority action is to reduce snaring, especially within strategic core areas. This will be a difficult undertaking as most protected areas in Viet Nam and Lao fail to provide effective protection for ground-dwelling mammal species (Corbet, 2008, IUCN, lad.nafri.org.la/fulltext/2142-0.pdf). Given the difficulties of halting snaring, it may be prudent to start a captive population of the Annamite striped rabbit as it is not currently held in captivity.
Conservation stakeholders must act quickly to protect this little-known lagomorph. There is little doubt that, with continued extensive snaring across the Annamites, the species could drift silently into extinction.