Harrer, S., P. Ginal, W. C. Tan, J. W. Binaday, A. C. Diesmos, R. Manalo, T. Ziegler & D. Rödder

Disappearing archosaurs – an assessment of established protected areas in the Philippines to save the critically endangered, endemic Philippine Crocodile (Crocodylus mindorensis). pp. 29-41 plus Supplementary Table S1 and Supplementary Table S2.

Abstract. Once distributed all over the Philippines, the endemic Philippine Crocodile (Crocodylus mindorensis) is nowadays threatened with extinction. It is estimated that less than 140 mature individuals live in the wild. Human activities like fishing and poaching, as well as land-use change and habitat conversion cause a continuing threat to the remaining populations. Therefore, designated protected areas (PAs) were evaluated with species distribution models (SDMs) and also to see if most suitable areas are covered by PAs in order to improve future conservation efforts. For this purpose, the existing IUCN-reserves were analysed for potential habitat suitability (combining bioclimatic and remote sensing variables), wetland occurrences and the human footprint index by using MaxEnt and QGIS. Based on species records, our final SDM showed high performance and revealed the climatically most suitable areas for the species, which were mostly on Luzon and Mindanao. However, only small parts of the climatically suitable wetlands are currently covered by reserves (0.3–46.3%). In addition, none of the species’ records was located within a PA. The anthropogenic pressures in the reserves measured by human footprint index (considering eight variables i.e. ‘population density’, ‘navigable waterways’, ‘crop lands’ and ‘roads’) were diverse and varied between a low and moderate level. Most of the records were found in areas with a moderate human footprint. Considering the three criteria, ‘Lake Lanao Watershed Reservation’, ‘Angat Watershed Forest Reserve District (Metro Water District)’, ‘Northern Sierra Madre Natural Park’, ‘Talaytay Protected Landscape’ and ‘Agusan Marsh Wildlife Sanctuary’ revealed to be the most suitable conservation areas for C. mindorensis, whereas suitable areas outside PAs are highly recommended for further surveys. We recommend to declare Ligawasan Marsh, Mindanao as a PA as this area harbours a large population of C. mindorensis. The declaration of more climatically suitable areas with low level of human footprint to PAs is a necessary step for the long-term conservation of this endemic crocodile species. The current network of existing PAs needs improvement in order to provide well-suited and long-term protection for C. mindorensis. More surveys are also necessary to find hidden, so far overlooked populations and to assess C. mindorensis tolerance level for human impacts.

Key words. Crocodylia, species distribution modelling, human footprint index, wetlands, IUCN, MaxEnt, conservation, reptiles.