The Urban Avifauna Assemblage and Ecology of Selected Invasive Species in Western Sarawak, Borneo

Nurul Ashikeen, Ab Razak (2022) The Urban Avifauna Assemblage and Ecology of Selected Invasive Species in Western Sarawak, Borneo. PhD thesis, Universiti Malaysia Sarawak.

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Abstract

The general trend in urban biodiversity declines across the urban-rural gradient, which tends to accelerate as habitats become more urbanised. This study's primary purpose is to understand better the urban bird assemblage in Kuching and Kota Samarahan Divisions concerning how to manage invasive myna populations (Common myna and Javan myna). Increasing in some species may contribute to declining or rising of the other. It plays a significant role in improving the quality of the urban environment. It can also aid in predicting and possibly mitigating the effects of future urbanisation. The first component of this research is to quantify and compare the population density and habitat utilisation of urban birds. The focus is then shifted to determining the spatial and temporal variation of home range in Common and Javan mynas in human-modified environments. The resource partitioning and assemblage structure of the urban bird population and the behavioral ecology of both invasive mynas are described next. Finally, this research involves gathering information about the human community's perceptions on urban pest birds and how they are managed in Western Sarawak, Borneo. For the bird survey, line transect method, scan, and focal observation were used. At the same time, radio telemetry was used to determine the home range of the two invasive species. The result shows that the most abundant species recorded were invasive species, namely Rock pigeon, Common myna, Javan myna and Eurasian tree sparrow, while 39 indigenous species were observed throughout a 13-month sampling period. The result was congruent with the urban setting characterized by high buildings architectonically favorable for pigeon settlement. Exotic species mainly were limited to the metropolitan area, where the diversity and abundance of native species were poor. Exotic species have a higher density than indigenous species. It is indeed reasonable to infer that in nature; the species rarely interact. The Common myna has a slightly greater home range than the Javan myna. The result suggests that Common myna prefers to explore more resources than their cousin species. Frugivore, granivore, insectivore, nectarivore, omnivore, and purgamenovore are the six dietary guilds found among urban passerines in all 15 sampling locations in Kuching and its outskirts. Birds that have adapted successfully to human environments tend to forage near the ground in open areas. Indigenous and forest species, on the other hand, prefer to feed on trees away from predators and humans. From the human communities’ survey, 76% of local authorities in Kuching and Kota Samarahan district had verified non-native species and were aware of nuisance birds. Even still, only a few of the responders thought the birds were pests. Foraging activity, particularly food centers, has a significant impact on invasive species' home range. If the populations of these two invasive mynas continue to overgrow, their ranges may spread to include Sarawak's neighbouring divisions. Furthermore, because food is scarce in urban areas, indigenous feeding guilds may have evolved. Continuous monitoring of urban bird populations (both native and invasive species) and public awareness efforts are essential to maintain an equilibrium between urban growth and the sustainability of the natural environment.

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