Varanidae Indicator indicator 13 Ecosystems 12 Conservation 7 Forestry 6 Land use 6 anthropogenic effect 6 Biodiversity 5 Climate change 5 detection method 5 Birds 4 China 4 Economic and social effects 4 Indicator species 4 Monitoring 4 Vegetation 4 biodiversity 4 bioindicator 4 climate change 4 environmental monitoring 4 index method 4 Ecology 3 Environmental protection 3 Europe 3 Invertebrata 3 Population statistics 3 Rivers 3 Surveys 3 eDNA 3 endangered species 3