How the bird community of 19 rainforest fragments shifted across six survey seasons between 2000 and 2019 — who rose, who declined, and what fragmentation did to forest specialists and endemics.
Each season counted a different number of points, so raw counts can't be compared directly — every analysis below works in proportions or per-point rates to correct for it.
Raw species counts reward whoever counted more birds. Rarefaction rebuilds each season's expected richness as if only the same number of individuals had been sampled, so the seasons become directly comparable. Each curve is one season; the dashed line marks the common sample size all are compared at.
Counted raw, 2019 led with 106 species — but it also logged 10,354 individuals, ten times the smallest season. Rarefied to a common 1,042 birds, 2000 is the most diverse season (82 species) and 2019 falls to mid-pack (~78). The apparent richness gain was a sampling artefact.
Each band is a species' share of all individuals counted that season. The "all other species" pool — every bird outside the 12 commonest — shrank from 55% to 36%, meaning a handful of abundant generalists now dominate.
Pick a species to see its share of the community, its occupancy (the % of survey points where it turned up), and how many individuals were counted each season.
Tracking three signatures of forest health over time: Western Ghats endemics, rainforest specialists vs open-country birds, and the seasonal influx of migrants. The slow erosion of the endemic share is the line to watch.
The species–area relationship, split by habitat. Each bubble is a fragment (bubble size = survey effort), placed by area on a log scale. Rainforest specialists climb steeply with fragment size, while open-country birds run the opposite way — small, edge-dominated patches actually hold more of them. The two trend lines cross, and that divergence is the fingerprint of fragmentation.
Two views. First, an occupancy matrix — every species against every fragment, coloured by the share of points in that fragment where the species turned up. Scroll the species axis to explore all 130. Then a spatial grid for any single species, built from the 732 GPS-tagged survey points of the 2019 season.
Splitting the fragments at the median area (100 ha) into small and large groups, and comparing the share of endemics, forest specialists and migrants in each, across every season.