Survey sites
We surveyed four river catchments: i) Danum Valley (5°N, 118°E); ii) Endau (2°N, 103°E); iii) North Selangor peat swamp forest (NSPSF) (4°N, 101°E); and iv) Nee Soon (1°N, 103°E) (Fig. 1). Each catchment was sampled twice, once between 1990–1996 (before ) and once between 2015–2018 (after ).