Jungle Giants: Assessing Sustainable Harvesting in a Difficult-to-Survey Species (Python reticulatus)

Abstract

Sustainability of wildlife harvests is critical but difficult to assess. Evaluations of sustainability typically combine modelling with the measurement of underlying abundances. For many taxa harvested in developing countries, however, abundances are near-impossible to survey and a lack of detailed ecological information impedes the reliability of models. In such cases, repeated surveys of the attributes of harvested individuals may provide more robust information on sustainability. If the numbers, sizes and other demographic attributes of animals taken for the commercial trade do not change over biologically significant time intervals (decades), there is a prima facie case that the harvest is indeed sustainable. Here, we report the results of examinations of > 4,200 reticulated pythons (Python reticulatus) taken for the commercial leather industry in northern and southern Sumatra, Indonesia. The numbers, mean body sizes, clutch sizes, sizes at maturity and proportion of giant specimens have not decreased between our first surveys (1995) and repeat surveys (2015). Thus, despite assumptions to the contrary, the harvest appears to be sustainable. We use our data to inform the design of future monitoring programs for this species. Our study underpins the need for robust science to inform wildlife trade policy and decision-making, and urges wildlife managers to assess sustainability of difficult-to-survey terrestrial wildlife by drawing inferences directly from the harvest itself.

The Plight of Reptiles as Ecological Actors in the Tropics

“…Opposed to the opinions of those who study mammalian carnivores, crocodilians are the largest predators in tropical regions on all continents. Indeed, within a given area, pythons and crocodilians can surpass mammalian carnivores both in numbers and biomass by several orders of magnitude Natusch et al, 2016). Squamate reptiles, like snakes, are capable of overpowering bird and mammalian prey ( Figure 1B).…”

“…Squamate reptiles, although capable of sustaining high cropping rates (Natusch et al, 2016), have also lost several species. Besides the widespread extirpation of the relictly insular Komodo dragon, the largest lizard species (Varanus priscus, averaging 320 kg and toping 7 m in length; Molnar, 2004) was eliminated in Sahul during human colonization (Flannery, 2002).…”

“…In tropical ecosystems reptiles can achieve standing biomasses that equal or surpass that of any other air-breathing vertebrate Natusch et al, 2016). We can only wonder how abundant they were before humanity's extraordinary capacity as a predator (Darimont et al, 2015) overexploited these populations, in many cases terminally.…”

Snapshot of an On-Going Trade in Reptile Wholesaler, Kebumen, Central Java: Preparation, Trading, and Conservation Implications

“…The high demand of accessories and products derived from reptiles correlates with the level of trafficking in the wild, which is on the same time, the evaluation of reptile's population and distribution is difficult to conduct [1]. In this case, wholesaler plays a vital role by distributing the captured animals to poacher, trader, and exporter in regional and national level.…”

“…Indonesia, as one of the biggest country in illegal trading and exporting products derivated from reptiles, receives an enormous economic benefits from trading activities [1]. On the other hand, Indonesia has been registered in CITES (Convention on International Trade in Endangered Species of Wild Fauna and Flora) treaty which regulates the export of endangered and threatened species since 1979 [3].…”