Biology subjects

Koane, B.

Publications and source records attributed to Koane, B..

5 recordsLinked to original sources

bioRxiv2025

Checklist of the birds of Wanang Conservation Area, Papua New Guinea

The Wanang Conservation Area in Papua New Guinea represents a large, community operated protected lowland rainforests. Based on surveys conducted in both the wet (November) and dry (July) seasons between 2010 and 2011, we report a total of 147 bird species known in the area around Swire station. Based on these surveys, we provide abundances of 120 bird species recorded during the standardized point-counts and mist-netting. Further, we add notes on the observations of another 27 bird species which we detected in the region outside of the standardized surveys. Finally, we compare our results with previous (2009) and later shorter surveys conducted in the region (2013 and 2019). In total, we document a cumulative total of 153 bird species recorded in the area to date.

zoology↗

bioRxiv2022

Reorganization of bird communities along a rainforest elevation gradient during a strong El Nino event in Papua New Guinea

The El Nino 2015 event, most extreme since 1997, led to severe droughts in tropical wet Papua New Guinea (PNG), reducing May to October dry season rainfall by - 75% in the lowlands and 25% in the highlands. Such droughts are likely to have significant effects on terrestrial ecosystems, but they have been poorly explored in Papua New Guinea. Here we report changes in bird community composition prior, during and after 2015 El Nino event along the elevational gradient ranging from 200 m to 2,700 m a.s.l. at the Mt. Wilhelm rainforest in PNG. The abundance of birds in lowlands dropped by 60% but increased by 40% at elevations above 1700m during El Nino year. In the following year, the individual bird species reached mean population sizes similar to pre-El Nino years but did not fully recover. Species richness roughly followed the pattern of observed abundance and quickly and fully re-established after the event to the pre-El Nino values. Thus, at least some terrestrial birds seem to react quickly to the extreme droughts in lowlands and shifted to less affected mountain habitats. We recorded upper elevational range limits to shifts by more than 500m asl in 22 bird species (out of 237 recorded in total) during El Nino year, in contrast to their typical ranges. Our study suggests that a strong El Nino event can have strong but reversible effects on bird communities as long as they have an opportunity to move to more favourable sites through undisturbed habitats.

ecology↗

bioRxiv2022

Vertebrates but not ants protect rainforest trees from herbivorous insects along an elevational gradient in Papua New Guinea

AimThe theory on trophic interactions between plants, insect herbivores, and their predators predicts that predators increase plant biomass by feeding on herbivores. However, it remains unclear whether different types of predators regulate herbivores to the same degree, and how the trophic interactions affect lower trophic levels along elevational gradients where predator communities differ significantly. Therefore, we aimed to investigate the impact of vertebrate predators and ants (individually and in combination) on arthropod communities and leaf herbivory along a complete tropical forest gradient. LocationPapua New Guinea TaxonMulti-taxon MethodsWe excluded predators from 560 saplings in two six-month long predator exclusion experiments spanning wet and dry seasons. Saplings were spread across 8 study sites which were evenly spaced at 500 m elevational increments from 200 to 3700m a.s.l.. ResultsOn average the density of arthropods increased significantly by 37% and 33% respectively when vertebrate predators, and both ants and vertebrates predators, were removed. Both season and elevation mediated this effect significantly. At lower trophic levels, both the exclusion of both vertebrates alone, and exclusion of vertebrates plus ants, led to a significant increase in leaf damage by 50% and 36% respectively. In contrast, the exclusion of ants alone had no significant effect on arthropod density or leaf damage, which increased by 12% and 9% respectively. Main conclusionsOur results indicate that the relative contribution of birds and bats changes at different elevational sites, while the overall effect of vertebrate predators remains consistent along the whole elevational gradient. This contrasts with ant driven trophic cascades which brought about increased herbivory only at the most productive sites of the elevational gradient, where ant abundance is highest. We conclude that disappearance of insectivorous vertebrate predators can lead to substantial negative consequences for plants.

ecology↗

bioRxiv2022

Population genomics of the island thrush elucidates one of earth's great archipelagic radiations

Tropical islands are renowned as natural laboratories for evolutionary study. Lineage radiations across tropical archipelagos are ideal systems for investigating how colonization, speciation, and extinction processes shape biodiversity patterns. The expansion of the island thrush across the Indo-Pacific represents one of the largest yet most perplexing island radiations of any songbird species. The island thrush exhibits a complex mosaic of pronounced plumage variation across its range, and is arguably the worlds most polytypic bird. It is a sedentary species largely restricted to mountain forests, yet it has colonized a vast island region spanning a quarter of the globe. We conducted comprehensive sampling of island thrush populations and obtained genome-wide SNP data, which we used to reconstruct its phylogeny, population structure, gene flow, and demographic history. The island thrush evolved from migratory Palearctic ancestors and radiated explosively across the Indo-Pacific during the Pleistocene, with numerous instances of gene flow between populations. Its bewildering plumage variation masks a biogeographically intuitive stepping stone colonization path from the Philippines through the Greater Sundas, Wallacea and New Guinea to Polynesia. The island thrushs success in colonizing Indo-Pacific mountains can be understood in light of its ancestral mobility and adaptation to cool climates; however, shifts in elevational range, degree of plumage variation and apparent dispersal rates in the eastern part of its range raise further intriguing questions about its biology.

evolutionary biology↗

bioRxiv2019

Biomass, abundances, and abundance and range size relationship of birds along a rainforest elevational gradient in Papua New Guinea

The usually positive inter-specific relationship between geographical range size and the abundance of local bird populations comes with exceptions. On continents, the majority of these exceptions have been described from tropical montane areas in Africa, where geographically-restricted bird species are unusually abundant. We asked how the local abundances of passerine and non-passerine bird species along an elevational gradient on Mt. Wilhelm, Papua New Guinea relate to their geographical range size. We collected data on bird assemblages at eight elevations (200 - 3,700 m, at 500 m elevational increments). We used a standardized point-counts at 16 points at each elevational study site. We partitioned the birds into feeding guilds, and we obtained data on geographical range sizes from Bird-Life International data zone. We observed a positive relationship between abundance and geographical range size in the lowlands. This trend changed to a negative one towards higher elevations. The total abundances of the assemblage showed a hump-shaped pattern along the elevational gradient, with passerine birds, namely passerine insectivores, driving the observed pattern. In contrast to abundances, the mean biomass of the bird assemblages decreased with increasing elevation. Our results show that montane bird species maintain dense populations which compensate for the decreased available area near the top of the mountain.

ecology↗