Status of the Daito Scops Owl on Minami-daito Island, Japan

Takagi, Masaoki; Akatani, Kana; Matsui, Shin; Saito, Atsushi

doi:10.3356/0892-1016(2007)41[52:sotdso]2.0.co;2

Cited by 21 publications

(28 citation statements)

References 3 publications

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“…Taking IBD pattern into account, significant between‐cluster differences in geographic position detected by AMOVA also supports clusters being groups of relatives. Our samples include relatives because of the following properties: (1) The entire population consists of a relatively small number of individuals (estimated to be about 210 pairs; Takagi et al ., ); (2) We sampled as many individuals as we could from this small population; (3) Because their life span is 3 to 4 years and they breed every year, many familial individuals coexist in the population at the same time.…”

Section: Discussionmentioning

confidence: 99%

“…(1) The entire population consists of a relatively small number of individuals (estimated to be about 210 pairs; Takagi et al, 2007a); (2) We sampled as many individuals as we could from this small population; (3) Because their life span is 3 to 4 years and they breed every year, many familial individuals coexist in the population at the same time.…”

Section: Discussionmentioning

confidence: 99%

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Fine‐scale spatial genetic structure in the Minami‐daito Island population of the Ryukyu scops owl Otus elegans

2018

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Multiple factors can give rise to population genetic structure. Therefore, the generating process of genetic structure should be examined from multiple aspects simultaneously. We describe the fine‐scale genetic structure of the Ryukyu scops owl Otus elegans interpositus population on Minami‐daito Island and test isolation‐by‐distance, isolation‐by‐adaptation and assortative mating as candidates for its underlying mechanisms. Spatial principal component analysis detected a spatial autocorrelation structure for males, but not for females. Discriminant analysis of principal components and STRUCTURE analysis allowed us to classify the owl population into six genetically distinct groups. These clustering results were associated with relatedness. In addition, to these descriptive analyses, analyses of mechanisms preferred isolation‐by‐distance to others. Therefore, we inferred that isolation by distance and kinship structure are the most important underlying processes leading to their genetic structure.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Fine‐scale spatial genetic structure in the Minami‐daito Island population of the Ryukyu scops owl Otus elegans

2018

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“…Owls tend to be more vocally responsive during the breeding season (Haug & Didiuk 1993;Moulton et al 2004) but such behaviour decreases throughout the nesting season (Boal & Bibles 2001). Males may cease singing almost immediately after pairing in courtship (Konig & Weick 2008) while females may become less vocally responsive during the incubation period (Haug & Didiuk 1993;Takagi et al 2007a). This is likely to happen when territories and nest have already been established and thus conspecific intruders may no longer be a threat.…”

Section: Discussionmentioning

confidence: 99%

“…Density overestimation may occur when: Individuals lured by call playback moved to a different location (Moulton et al 2004;Wiens et al 2011) and thus counted more than once (Borges et al 2004;Hannah 2009) and/or; An owl species may have different vocal responses to playback and this can influence the actual count (Borges et al 2004;Wiens et al 2011). On the other hand, underestimation of density may occur when certain individuals did not react to call playback (Hannah 2009;Haug & Didiuk 1993;Takagi et al 2007a). In our study, several measures were taken to minimise the risk of density overestimation such as positioning the speaker at chest level and rotating it at 360° to ensure the call was broadcasted to all directions and within the forest understory level at which the owls were active (Konig & Weick 2008).…”

Section: Discussionmentioning

confidence: 99%

“…passive listening and/or active call broadcasting) are frequently used in detecting elusive species (Johnson et al 1981;Marion et al 1981) including owls which often react to the conspecific call playbacks (Pardieck et al 1996;Wiens et al 2011). These vocal responses from owls could also aid in assessing their sexes (Odom & Mennil 2010;Takagi et al 2007a) and breeding success (Hardouin et al 2009). …”

Section: Introductionmentioning

confidence: 99%

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Sunda Scops-Owl Density Estimation via Distance Sampling and Call Playback

Pilla

Chong

Lim

et al. 2018

JSM

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Missing piece of top predator‐based conservation: Demographic analysis of an owl population on a remote subtropical island

et al. 2021

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Top predators are frequently the target of conservation programs. Owls are such predators. However, previous studies of owls are biased to species occurring in temperate regions, whereas most owl species occur in tropical or subtropical regions and are understudied. Furthermore, owls are often endemic to islands and of unknown conservation status. Demographic data for such species are especially scarce although they are essential for initiating and promoting their conservation. As a case study of demographic analysis of owls in a tropical or subtropical area and on islands, we applied an integrated population model to 7‐year monitoring data (2012–2018) of the Ryukyu Scops Owl population on Minami‐daito Island, Japan. We used survival history data from 903 individuals, reproduction and sex ratio data from 213 broods, and count data of 2,526 individuals in total. Long‐term averages of annual survival rates were 0.73 for adult females and 0.74 for adult males, although the sexual difference was not significant. Sex ratio estimates fluctuated annually and long‐term averages were slightly skewed to males: 0.51 among fledglings, 0.54 among yearlings, and 0.52 among adults. Long‐term averages of population size were estimated to be 273.4 females and 296.8 males. The long‐term average of population growth rate was 0.98, suggesting a slightly declining trend. It was fortunate to recognize the declining trend during the early phase. Considering the general lack of fundamental ecological data on owls of tropical or subtropical areas and on islands, it seems likely that many endangered owl populations await conservation efforts.

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Status of the Daito Scops Owl on Minami-daito Island, Japan

Cited by 21 publications

References 3 publications

Fine‐scale spatial genetic structure in the Minami‐daito Island population of the Ryukyu scops owl Otus elegans

Fine‐scale spatial genetic structure in the Minami‐daito Island population of the Ryukyu scops owl Otus elegans

Sunda Scops-Owl Density Estimation via Distance Sampling and Call Playback

Missing piece of top predator‐based conservation: Demographic analysis of an owl population on a remote subtropical island

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