Persistence of a locally endangered mouse-deer amidst the re-emergence of two larger ungulates in small urban rainforest fragments

Khoo, Max; Lim, Bryan. T.M.; Soh, Malcolm C. K.; Lua, H.K.; Lee, Benjamin. P.Y.-H.; Loo, Adrian H. B.; Er, Kenneth B. H.

doi:10.1016/j.gecco.2021.e01807

Cited by 6 publications

(7 citation statements)

References 58 publications

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“…Muntjac deer ( Muntiacus muntjak ) has never been recorded with certainty before 2014 in Singapore, although there are some anecdotal and unconfirmed sightings in the late 1990s, supported by local wildlife expert input and literature (Teo & Rajathurai, 1997). However, we confirmed two separate muntjac camera trap capture events in the southern areas of the MacRitchie area of the CCNR, with one photo in 2014 and one in 2015 (Khoo et al, 2021). Subsequent and more intense camera trapping in the same region in 2018, 2019, and 2020 detected no muntjac deer.…”

Section: Resultssupporting

confidence: 78%

“…There was substantial evidence that sambar deer recolonization occurred through escape from private and public zoos in the early 1970s (Chua, 2011; Huiwen, 2019). Other reports have suggested sambar deer escaped from a local captive source (Khoo et al, 2021), potentially the Singapore Zoo which is in the Mandai section of the CCNR (Figure 2b), and the Mandai forest area is also where sambar deer were first spotted in 1973. Sambar deer were not observed outside of the Mandai forested region surrounding the zoo until the 2000s when they progressively occupied the eastern CCNR and finally began appearing in Bukit Timah in 2011 (Figures 2, 3).…”

Section: Resultsmentioning

confidence: 84%

“…captive source (Khoo et al, 2021), potentially the Singapore Zoo which is in the Mandai section of the CCNR (Figure 2b), and the Mandai forest area is also where sambar deer were first spotted in 1973. Sambar deer were not observed outside of the Mandai forested region surrounding the zoo until the 2000s when they progressively occupied the eastern CCNR and finally began appearing in Bukit Timah in 2011 (Figures 2, 3).…”

Section: Sambar Deer Recolonization Dispersal and Relative Abundances...mentioning

confidence: 99%

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Rewilding in Southeast Asia: Singapore as a case study

Lamperty

Chiok

Khoo

et al. 2023

Conservat Sci and Prac

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Re‐establishing extirpated wildlife—or “rewilding”—is touted as a way to restore biodiversity and ecosystem processes, but we lack real‐world examples of this process, particularly in Southeast Asia. Here, we use a decade of aggregated camera trap data, N‐mixture occupancy models, and input from local wildlife experts to describe the unassisted recolonization of two native large herbivores in Singapore. Sambar deer (Rusa unicolor) escaped from captivity (in private or public zoos) in the 1970s and contemporary camera trap data show they have only colonized nearby forest fragments and their abundance remains low. Wild pigs (Sus scrofa), in contrast, naturally recolonized by swimming from Malaysia in the 1990s and have rapidly expanded their range and abundance across Singapore. While wild pigs have not recolonized all viable green spaces yet, their trajectory indicates they soon will. We also note that a third ungulate, the muntjac deer (Muntiacus muntjak), was captured in camera trapping in 2014 and 2015 but was never recorded afterward despite increased sampling effort, and thus we do not focus on their presumably unsuccessful recolonization. The divergent rewilding trajectories between sambar deer and wild pigs suggest different conservation outcomes and management requirements. Sambar deer may restore lost plant–animal interactions such as herbivory and seed dispersal without requiring significant management. Wild pigs, in contrast, have reached high numbers rapidly and may require active management to avoid hyperabundance and negative ecological impacts in regions, such as Singapore that lack both hunting and large predators.

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Section: Resultssupporting

confidence: 78%

Section: Resultsmentioning

confidence: 84%

Section: Sambar Deer Recolonization Dispersal and Relative Abundances...mentioning

confidence: 99%

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Rewilding in Southeast Asia: Singapore as a case study

Lamperty

Chiok

Khoo

et al. 2023

Conservat Sci and Prac

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“…From February 2015 to October 2017, females from the general population in Singapore who were attempting to conceive were recruited to participate in the S-PRESTO prospective cohort study. 7 Recruitment involved social media advertisements, community leaflet distributions, and invitation letters mailed to female patients of reproductive age who were registered at KK Women's and Children's Hospital in the past 5 years and were currently not receiving active treatment. Inclusion criteria were 18 to 45 years of age; Chinese, Indian, or Malay ethnicity (self-identified); and attempting conception within the next 12 months.…”

Section: Study Participants and Proceduresmentioning

confidence: 99%

Modifiable Risk Factor Score and Fecundability in a Preconception Cohort in Singapore

Loy

Tiong

et al. 2023

JAMA Netw Open

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ImportanceAlthough multiple modifiable risk factors have been identified for reduced fecundability (defined as lower probability of conception within a menstrual cycle), no scoring system has been established to systematically evaluate fecundability among females who are attempting to conceive.ObjectiveTo examine the association of a risk score based on 6 modifiable factors with fecundability, and to estimate the percentage reduction in incidence of nonconception if all study participants achieved a minimal risk score level.Design, Setting, and ParticipantsThis population-based cohort study obtained data from the S-PRESTO (Singapore Preconception Study of Long-Term Maternal and Child Outcomes) prospective cohort study. Females of reproductive age who were trying to conceive were enrolled from February 2015 to October 2017 and followed for 1 year, ending in November 2018. Data were analyzed from March to May 2022.ExposuresA reduced fecundability risk score was derived by giving participants 1 point for each of the following factors: unhealthy body mass index, unhealthy diet, smoking, alcohol intake, folic acid supplement nonuser, and older maternal age. Total scores ranged from 0 to 6 and were classified into 5 levels: level 1 (score of 0 or 1), level 2 (score of 2), level 3 (score of 3), level 4 (score of 4), and level 5 (score of 5 or 6).Main Outcomes and MeasuresFecundability, measured by time to conception in cycles, was analyzed using discrete-time proportional hazards models with confounder adjustment.ResultsA total of 937 females (mean [SD] age, 30.8 [3.8] years) were included, among whom 401 (42.8%) spontaneously conceived within 1 year of attempting conception; the median (IQR) number of cycles before conception was 4 (2-7). Compared with participants with a level 1 risk score, those with level 2, 3, 4, and 5 risk scores had reductions in fecundability of 31% (adjusted fecundability ratio [FR], 0.69; 95% CI, 0.54-0.88), 41% (FR, 0.59; 95% CI, 0.45-0.78), 54% (FR, 0.46; 95% CI, 0.31-0.69) and 77% (FR, 0.23; 95% CI, 0.07-0.73), respectively. Assessment of the population attributable fraction showed that all participants achieving a minimal (level 1) risk level would be associated with a reduction of 34% (95% CI, 30%-39%) in nonconception within a year.Conclusions and RelevanceResults of this study revealed the co-occurrence of multiple modifiable risk factors for lowered fecundability and a substantially higher conception rate among participants with no or minimal risk factors. The risk assessment scoring system proposed is a simple and potentially useful public health tool for mitigating risks and guiding those who are trying to conceive.

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“…Their recolonization has been facilitated by forest restoration efforts in Singapore aiming to restore its degraded biodiversity and ecosystems, which have provided increasing secondary forest cover and thus suitable habitats for pigs (Lamperty et al, 2023;Shono et al, 2006). Singapore's pigs have slowly spread across most parts of the island and have reached high densities in some early recolonized forests (Khoo et al, 2021;Lamperty et al, 2023). Pig densities are expected to rise given the hunting ban, lack of predators, and food subsidies from crops and urban areas, and their accumulated soil and vegetation disturbances can become deleterious to the local forest ecology (Amir et al, 2022;Luskin et al, 2019Luskin et al, , 2021Moore et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

Recolonizing native wildlife facilitates exotic plant invasion into Singapore's rain forests

Ho,

Dehaudt,

Lee

et al. 2023

Biotropica

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Halting biological invasions and rewilding extirpated native fauna are conservation interventions to bolster biodiversity, species interactions, and ecosystems. These actions are often considered separately and the potential for reintroduced wildlife to facilitate invasive plants has been largely overlooked. Here, we investigated the role of Singapore's recolonizing native wild pigs (Sus scrofa) in facilitating an invasive weed Miconia crenata into tropical rainforests, which are normally highly resistant to invasion. We conducted line‐transect surveys in 11 Singaporean rain forests and used generalized linear mixed models to consider the contribution of pigs' soil disturbances, human forest paths, and other environmental covariates, on the density of M. crenata. We found that M. crenata was more abundant at forest edges and invasion into forest interior was facilitated by pigs, paths, and canopy gaps, but that these effects were all additive, not synergistic (i.e., not multiplicative). These results highlight how modern invasions are driven by multiple disturbances as well as propagule pressure (e.g., urban birds dispersing seeds at forest edges where they establish in pig soil disturbances). Singapore's extensive native forest restoration efforts may have provided plentiful edge and secondary forests that are well suited to pigs and M. crenata, which in turn undermine the aims of fostering later‐successional native plant communities. To prevent negative externalities, we suggest that plant restoration and rewilding projects consider the potential role of wildlife in facilitating non‐native plants, and couple these actions with preliminary screening of unintended consequences and continued monitoring, as well as limiting human‐mediated weed invasion to minimize propagule sources.

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Persistence of a locally endangered mouse-deer amidst the re-emergence of two larger ungulates in small urban rainforest fragments

Cited by 6 publications

References 58 publications

Rewilding in Southeast Asia: Singapore as a case study

Rewilding in Southeast Asia: Singapore as a case study

Modifiable Risk Factor Score and Fecundability in a Preconception Cohort in Singapore

Recolonizing native wildlife facilitates exotic plant invasion into Singapore's rain forests

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