Sunda scops-owl density estimation via distance sampling and call playback

Nocturnal birds in the tropics remain little studied primarily due to the logistical difficulties of surveying these birds at night. While call playback has been widely employed in the temperate regions, its practicality has not been adequately demonstrated on tropical owl species. This study aimed to test the feasibility of estimating the density of the Sunda scops-owl (Otus lempiji) in a lowland forest in Peninsular Malaysia based on call playback and distance sampling. From a total of 58 detections of the owl species from October 2012 to May 2013, 72.41% (42 detections) were made when the birds were breeding. The densities of the owl were estimated at 1.6 individuals and 2.6 individuals per 10 ha based on spontaneous and provoked calls (i.e. before and after call playback), respectively. Broadcasting of the calls significantly increased the numbers of detections (χ2 = 16.038, p<0.001) during both breeding and non-breeding seasons of the birds. The combination of call playback and distance sampling improved the detectability as well as precision of the owl’s density estimation and can be potentially applied on other little known owl species in Southeast Asia

Home range and activity patterns of Sunda scops owl in Peninsular Malaysia

The Sunda scops owl Otus lempiji is commonly found in many wooded habitat types in Malaysia. However, as with other owl species in Southeast Asia, there is a lack of published ecological studies. We examined the home range and activity patterns of six adult Sunda scops owls based on radio-telemetry in an isolated forest, namely Ayer Hitam Forest Reserve, Selangor, Peninsular Malaysia from December 2012 to June 2013. Mean minimum convex polygon and harmonic mean home range areas of the owls were 2.40 ± 0.28 SD ha and 4.00 ± 0.78 SD ha, respectively. The birds exhibited territorial behaviour with little overlapping of home ranges. Movements (the means of inter-fix speed) were not associated with lunar illumination nor with time. This study provided baseline information on the spatial requirements of the Sunda scops owl in a lowland forest

Sunda scops-owl density estimation via distance sampling and call playback

Nocturnal birds in the tropics remain little studied primarily due to the logistical difficulties of surveying these birds at night. While call playback has been widely employed in the temperate regions, its practicality has not been adequately demonstrated on tropical owl species. This study aimed to test the feasibility of estimating the density of the Sunda scops-owl (Otus lempiji) in a lowland forest in Peninsular Malaysia based on call playback and distance sampling. From a total of 58 detections of the owl species from October 2012 to May 2013, 72.41% (42 detections) were made when the birds were breeding. The densities of the owl were estimated at 1.6 individuals and 2.6 individuals per 10 ha based on spontaneous and provoked calls (i.e. before and after call playback), respectively. Broadcasting of the calls significantly increased the numbers of detections (χ2 = 16.038, p<0.001) during both breeding and non-breeding seasons of the birds. The combination of call playback and distance sampling improved the detectability as well as precision of the owl’s density estimation and can be potentially applied on other little known owl species in Southeast Asia

Can forest associated nocturnal birds persist in oil palm agroecosystem?

A high demand for palm oil has led to the continued expansion of oil palm agriculture at the expense of tropical forests and forest biotic communities in many developing countries. The response of wildlife to oil palm establishment has been shown to vary according to taxa, and many forest species may not be able to adapt to the altered landscape. Many nocturnal bird species have been recorded in oil palm agriculture. Whether such forest species can also thrive in such a landscape is not known, and their responses to habitat complexity are poorly understood. We conducted point surveys of nocturnal birds (Tytonidae, Strigiformes and Caprimulgiformes over 80 points spaced at least 800 m apart and revisited five times) in oil palm smallholdings at Tanjung Karang, Kuala Selangor. Environmental factors measured at each point included: average height of oil palm stands, palm density, crop richness, and distances to the nearest forest, river and road. We recorded a total of 577 individuals of seven species. Palm density and distance to river were found to positively influence nocturnal bird species richness, whereas distance to the nearest forest was found to negatively influence avian species richness. In the case of abundance, number of oil palms, crop richness, and distance to the nearest river were found to influence nocturnal bird abundance positively in the smallholdings; however, distance to the nearest forest was found to influence bird abundance negatively. These findings suggest that maintaining key vegetation structure while reducing manmade structures such as roads may benefit nocturnal bird species in the smallholdings particularly those of open and semi-open habitats. However, the number of forest-associated species remained low in the smallholdings, which may only serve as suboptimal habitat for these birds. This implies that forest-associated species may not be able to persist in such landscapes

Contribution of illegal hunting, culling of pest species, road accidents and feral dogs to biodiversity loss in established oil-palm landscapes

Context: Understanding the ecological impacts of the palm-oil industry on native fauna requires information on anthropogenic threats that may cause species decline or local extinction. Aim: The main aim of the study was to assess wildlife deaths caused by illegal hunting, road accidents and introduced predators in established oil-palm landscapes in Peninsular Malaysia. Methods: Between April and October 2009, we interviewed 362 oil-palm workers at 36 sites, including large industrial estates and semi-traditional smallholdings. Key results: Our results showed that (1) illegal hunting by oil-palm workers in different oil-palm management systems was not statistically significant (P = 0.097), (2) native fauna were more often destroyed as pests in smallholdings than in conventional and eco-friendly plantation estates (P = 0.005), (3) non-local poachers conducted illegal activity more often in smallholdings than in conventional and eco-friendly plantation estates (P = 0.011), (4) road accidents were reported to kill more native fauna in conventional plantation estates than in smallholdings and eco-friendly plantation estates (P < 0.001) and (5) feral dogs were reported as killing more native fauna in eco-friendly plantation estates than in conventional plantation estates and smallholdings (P = 0.034). Conclusion: In addition to the conversion of native forest to oil-palm monocultures, various other anthropogenic threats can have a substantial effect on wildlife in oil-palm landscapes. Implications: To improve the conservation value of oil-palm landscapes, we recommend that palm-oil stakeholders should implement anti-poaching patrols, organise conservation programs to educate workers, reduce vehicle speeds on roads within oil-palm landscapes, and control local populations of feral dogs

Cattle grazing benefits farmland bird community composition in oil palm plantations

Oil palm expansion has caused considerable biodiversity loss as rainforest has been converted to plantation. However, it is still possible to mitigate such biodiversity losses and increase agricultural sustainability by introducing sustainable oil palm farming practices. One such method is the use of biological control agents for understory weed management in place of herbicides. Integrating cattle into oil palm plantation management to control undergrowth is expected to improve biodiversity (including avian diversity) in oil palm plantations. This study investigated the association between cattle grazing and farmland bird species composition in oil palm plantations. We used point transect sampling to survey farmland birds in 45 oil palm plantations which were divided into systematically and non-systematically cattle grazed plantations and control plantations (without cattle grazing). We found that both oil palm plantations with systematic (P=0.001) and non-systematic (P=0.005) cattle grazing had greater avian diversity than plantations without cattle grazing. Based on feeding guild, avian insectivores made up the majority of farmland birds observed. Bird species composition was determined by four attributes in our model: number of cattle, selective weeding frequency, age of oil palm stand, and palm height. We conclude that systematic grazing can improve avian diversity in oil palm plantations. We stress, that cattle integration into oil palm agriculture can provide an excellent means of maximising agricultural land use efficiency as well as increasing biodiversity in agricultural landscapes by increasing habitat complexity

Effects of monoculture and polyculture farming in oil palm smallholdings on terrestrial arthropod diversity

Oil palm agriculture has become one of the economic mainstays for biodiversity-rich countries in the tropics. The conversion of native forests to oil palm monoculture plantation has caused unprecedented biodiversity loss in Southeast Asia. Little is known about the effects of oil palm polyculture farming on arthropod diversity. In this study, arthropods were sampled using pitfall traps at 120 sites in Peninsular Malaysia. We examined how arthropod biodiversity responded to different oil palm farming practices and local-scale vegetation structure characteristics. We found that the number of arthropod orders was significantly greater in polyculture than monoculture smallholdings. However, we did not detect a significant difference in arthropod order composition nor abundance between monoculture and polyculture practices. In situ habitat characteristics explained 16% of the variation in arthropod order richness, with key predictor variables including farming practice, height of oil palm stands, and number of immature palm. The findings of this study suggest that polyculture farming together with management for in situ habitat complexity may be a useful strategy in supporting biodiversity within in oil palm plantations

Effects of in situ habitat quality and landscape characteristics in the oil palm agricultural matrix on tropical understory birds, fruit bats and butterflies

The expansion of commercial oil palm crop has modified much of the natural landscape, subsequently leading to biodiversity loss in Southeast Asia. Aside from large-scale oil palm monoculture plantations, self-managed oil palm smallholdings are also becoming common in palm oil producing countries, but less is known about how management of the smallholdings affects faunal biodiversity. We argue that it is critically important to understand the role of habitat complexity at the local and landscape scales for maintaining faunal biodiversity in oil palm smallholdings. We used passive sampling methods to survey understory birds, fruit bats, and butterflies in oil palm smallholdings on the west coast of Peninsular Malaysia. We quantified the diversity in each taxon and measured in situ habitat quality and landscape metrics. We found that oil palm smallholdings located near rice fields supported fewer bird species. Proximity to roads can give rise to bird and fruit bat richness. Bird and fruit bat richness declined at sites with high crop density. Fruit bat richness declined, but butterfly richness increased, with the height of oil palm stands. Butterfly richness declined with distance from riparian habitats. Decreased coverage and height of ground vegetation also negatively affected butterfly species richness. We also found that the number of farm houses is positively related to bird, fruit bat, and butterfly species richness. Of the three taxa, only butterfly richness was positively influenced by crop diversity. We found that habitat complexity enables smallholdings to support a diverse community of birds and butterflies, but not fruit bats. These findings imply that oil palm smallholdings can be managed in a conservation agricultural matrix, as the smallholdings were able to maintain farmland biodiversity