374 B. Tapley et al.


degradation through anthropogenic modification of fresh- water habitats, including through pollutant emissions and the alteration of flow regimes andwater turbidity from dam- ming (e.g. Liang et al., 2004; Wang et al., 2004; Dai et al., 2009). However, there has been no systematic attempt to de- termine the extent to which these two threat processes have each contributed to giant salamander declines in China. This limitation is compounded by a general lack of pub- lished data on the habitat requirements of giant salamanders in China, especially with regard to water parameters. Using environmental data associated with historical lo-


cality records, Chen et al. (2018) developed a habitat suitabil- ity model for Chinese giant salamanders based on elevation, forest cover, mean annual temperature and mean annual precipitation, which was broadly congruent with the esti- mated IUCN range map for Andrias davidianus (Liang et al., 2004). Anecdotally, Chinese giant salamanders are thought to inhabit clear, cool, slow to swift flowing streams of pH 6–7 in steep-sided, well-vegetated valleys that have caves in rocky banks (Wang et al., 2004). Water parameters, such as dissolved oxygen, alkalinity and nitrate, are among the known predictors of cryptobranchid salamander distri- bution in the USA (Pugh et al., 2016). Siltation is known to cause the loss of specific cryptobranchid microhabitats by embedding boulders (under which these salamanders find refugia) in stream substrate (Fobes, 1995); turbidity could therefore be an additional predictor of suitable habitat for cryptobranchid salamanders (Quinn et al., 2013).Water tem- perature (Buckley&Jetz, 2007;Grant et al., 2014), pH (Freda & Dunson, 1986; Grant et al., 2014), ammonia concentration (Weyrauch & Grubb, 2004), and flow rate (Welsh& Olivier, 1998) are known to influence the distribution and/or sur- vivorship of all life stages of other salamander species. Robust understanding of the microhabitat requirements


of Chinese giant salamanders and of the drivers of their de- cline in China is essential if appropriate conservation strat- egies are to be formulated and implemented. We therefore gathered a novel large-scale dataset during amulti-year field survey programme in China, obtaining data from both ecological surveys and community-based surveys of local ecological knowledge. Together, these multidisciplinary and independent data provide an important new baseline for understanding Chinese giant salamander microhabitat re- quirements, and for identifying the significance of habitat degradation and/or overexploitation as the primary drivers of population declines across their range.


Methods


We randomly selected 50 Chinese counties containing his- torical giant salamander records (Fei et al., 2006), and 50 further counties from a sample of all counties lacking historical records that contained .50% predicted suitable


FIG. 1 Sites in China surveyed for Chinese giant salamanders Andrias spp., with sites where salamanders were detected and not detected, the opportunistic survey site where a giant salamander was detected, and sites where direct evidence of giant salamander exploitation was detected.


giant salamander habitat based on the habitat suitability model ofChen et al. (2018).These siteswere distributed across 16 Chinese provinces or equivalent administrative units (Fig. 1; Supplementary Table 1).We selected sites with intact natural habitat (i.e. fast-flowingmountain streamswith ripar- ian forest cover and rocky substrates) for surveys in all coun- ties, with specific site selection for those most likely to be occupied by Chinese giant salamanders determined through discussion with local government fisheries offices or protect- ed area managers. Logistical issues prevented survey work in three of the randomly selected counties, so only 97 of the 100 selected sites were surveyed. In addition, we opportunis- tically surveyed an additional site within Guangwushan- Nuoshuihe Geopark National Nature Reserve in Nanjiang County, Sichuan Province, which contained .50% pre- dicted suitable habitat and had recent reports of giant salamanders. Fieldwork was conducted during 2013–2016 by teams


trained to undertake standardized field surveymethodology (Tapley et al., 2017), with surveys during May–October each year to coincide with inferred peak activity periods of Chinese giant salamanders (Okada et al., 2008). Ecological surveys covered a cumulative 1 km transect of suitable habi- tat at each site. At some sites, geographical barriers (e.g. waterfalls) prevented the completion of a continuous 1 km transect; in such cases, the survey teamcontinued the survey beyond the obstruction until a cumulative transect of 1 km had been completed. Surveys included trapping (passive searching) using baited crab traps set for a 48-hour period (see Tapley et al., 2017 for details), and active survey


Oryx, 2021, 55(3), 373–381 © The Author(s), 2021. Published by Cambridge University Press on behalf of Fauna & Flora International doi:10.1017/S0030605320000411


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