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

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

Estimating Sunda Scop Owl (Otus lempiji horsfield) density based on distance sampling and call playback, Peninsular Malaysia

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 distance sampling and call playback.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 0.17 ± 0.04 or 0.28 ± 0.06 individuals/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. Based on logistic regression analysis, the probability of detections was also significantly associated with the owl’s breeding period.The combination of call playback and distance sampling can be potentially applied on other little known and threatened owl species in Southeast Asia

Estimating density of Sunda Scops Owl using the call playback method

Owls are an important predator in the food web and their density may reflect their prey populations in an ecosystem. However, the density of owls in a forest is often very difficult to estimate. The objective of the study was to estimate the density of Sunda Scops Owl (Otus lempiji) at Ayer Hitam Forest Reserve, Puchong, Selangor using the call playback method. Nocturnal survey was conducted at 60 sampling points that were located 150-170 m apart. At each point, a 10-min silent listening was made before the broadcasting of owl calls for 2 min. Preliminary results indicated that the density of the owls was five individuals per 10 ha based on silent listening and two birds per 10 ha using the call playback method. The results implied that the owl density in the forest estimated based on the call playback method may be different as compared to that obtained through silent listening. Such a difference may be due to the behaviour of the owls in responding to their call during the breeding and non-breeding seasons

Preliminary estimation of Sunda Scops Owl home range in an isolated forest

The patterns of spatial usage by animals are often associated with their morphological, physiological and behavioural adaptations to environmental changes. The spatial requirements of most owl species in Malaysia are little known. This paper presented the preliminary results on the home range of Sunda Scops Owl (Otus lempiji) based on the radio-telemetry method conducted in the Ayer Hitam Forest Reserve, Puchong. The home range size of a single male owl based on 95 % Mean Harmonic calculation was 0.57 ha. The core area size based on 50 % Mean Harmonic calculation was 0.22 ha. After nine nights of tracking, one roosting site within the home range was identified. A better understanding of home range and ranging behaviour of a species such as owls is essential in their conservation as well as the management of protected areas