key: cord-0332633-w7ikplxz authors: Mynott, Holly Isabelle; Lee, David Charles; Santillan, Rhea Aranas; Jürgen Schwarz, Christian; Tacud, Benjamin; Fernandez, Arcel Dryden; Kerhoas, Daphne title: Population assessment and habitat associations of the Visayan Hornbill Penelopides panini in Northwest Panay, Philippines date: 2021-09-01 journal: bioRxiv DOI: 10.1101/2021.08.31.458333 sha: 77dcf18a758bbb050036190c9d14978920d1ef72 doc_id: 332633 cord_uid: w7ikplxz Background Seven out of 10 hornbill species in the Philippines are threatened with extinction. Among these is the Endangered Visayan hornbill Penelopides panini, found on Panay and Negros islands. Threatened by habitat loss and hunting, its population size is thought to have declined from 1,800 individuals 20 years ago to less than 1,000. However, a recent study on Negros estimated 3,564 individuals across three core forest blocks. This study aims to quantify the Visayan hornbill population size in and around the Northwest Panay Peninsula Natural Park (NWPPNP) on Panay, the largest contiguous low-elevation forest landscape remaining across its range, and its broad habitat associations across a gradient of environmental degradation. Methods Hornbills were surveyed using 10-minute Distance sampling point counts (n = 362) along transects (average length 1.1 km). Habitat variables were recorded, while habitat was classified into: primary forest, secondary forest, plantation or open habitat. Using Distance software, population densities were estimated for, and post-stratified by habitat, with the overall population estimate taken as a mean of habitat density estimates weighted by habitat area. Using logistic binary regression, hornbill occurrence was modelled against reduced habitat factors extracted from factor analysis of the habitat data. Results Surveys covered 204.4 km2 of the 374.8 km2 Northwest Panay Peninsula. Hornbills were not recorded in plantation or open habitats. The estimated density of hornbills was significantly higher in primary forest (17.7 individuals km−2 ± 29.7% CV) than in secondary forest (5.0 individuals km−2 ± 36.7 %CV; z = 9.538, P < 0.001). The overall population estimate is 2,231 individuals ± 24.4 %CV for the NWPPNP and environs, and 2,949 individuals ± 23.1 %CV for the entire Northwest Panay Peninsula. One habitat factor, described by increasing numbers of large trees, elevation and distance from the Park’s boundary, had a significant positive effect in explaining hornbill occurrence, with hornbills significantly more likely to occur in primary forest than the other habitat types. Conclusions Our study demonstrates the habitat preference of the Visayan hornbill, highlights the importance of the NWPPNP for the species’ conservation, and provides strong evidence for re-assessing the global population size. Estimates are given for the dataset truncated at w = 60 m. Three PCA factors explained 62.3% of the variance in the nine original habitat variables (Table 2 ; Figure 2 ). Factor 1 (27.5% of the explained variance in the original habitat variables) was associated with increasing numbers of large tree stems indicative of a closed canopy forest history, increasing elevation and distance from the Park's boundary, and decreasing prevalence of trees indicative of closing canopy or regenerating forest histories. Factor 2 (21.9%) explained a habitat gradient of increasing numbers of tree stems of all size classes, but particularly trees <100 cm DBH, and increasing elevation, canopy cover, and trees indicating a regenerating forest history. Factor 3 (12.9%) described a gradient of decreasing habitat recovery, with tree structures characteristic of past open canopy forest alongside a decreasing prevalence of trees indicative of a closed canopy or regenerating forest history. Factor 1 scores were significantly higher for both primary and secondary forest than plantation and open habitat, and higher for primary forest than secondary forest (F 3,86 = 32.000, P <0.001, with Bonferroni post hoc test). Factor 2 scores were significantly higher for both primary and secondary forest than plantation and open habitat (F 3,86 = 17.636, P <0.001, with Bonferroni post hoc test). Field Conservation Projects: Deforestation PESCP's Protection Program from 2002 to 2008 for the last substantial sized population of the Dulungan Hornbill Convention on Biological Diversity. Philippines -Main Details. 2020 Population density and habitat preferences of the Black-cheeked ant-tanager Habia atrimaxillaris Zum Bedrohungs-Status endemischer Vögel auf den Philippinen: eine Expedition der Ruhr-Universität Bochum United Nations Environment Programme World Conservation Monitoring Centre 2021 Notes on two species of endangered Philippine hornbills with an emphasis on breeding biology Panay Eco-Social Conservation Project (PanayCon) Nineteenth Annual Report Mousebirds to Hornbills Are populations of large-bodied avian frugivores on Luzon, Philippines, facing imminent collapse? Large avian frugivores in the Philippines show linear responses to improvements in forest quality Proclamation No. 414, s Tree cover in the Philippines United Nations Environment Programme World Conservation Monitoring Centre 2021 The wildlife snaring crisis: an insidious and pervasive threat to biodiversity in Southeast Asia Impacts of hunting on tropical forests in Southeast Asia Uncontrolled hunting and habitat degradation decimate and extirpate forest hornbills in Ghana Applied logistic regression Understanding the drivers of Southeast Asian biodiversity loss We would like to thank the Philippine Department Environment of Natural Resources, and especially Mr Andres Untal (PENRO) and Mme Cynthia Blancia (CENRO) and their staff. Special thanks for the data collection to the dedicated Ilke Geladi and the rest of the team.