Land use and oriental pied-hornbill occurrence in Singapore

Oriental Pied-Hornbills (Anthracoceros albirostris) disappeared from Singapore in the 1800s but were returned in the 2000s through a combination of active reintroduction and recolonization. Since then, they have multiplied and even thrived in Singapore, spreading throughout much of the country. Singapore is extremely urban and densely populated, and here we examine where hornbills have been seen as a function of land-use. We combine citizen science data from eBird and iNaturalist with GIS information to model hornbill occurrence. We find that vegetation with no canopy, marshy habitat, and built-up areas have strong positive effects on the probability of hornbill sightings. We interpret our results with respect to larger regional patterns.