Adrian H. B. Loo

Wildlife crossing structures and road calming measures are frequently implemented to improve habitat connectivity and mitigate the risks of wildlife–vehicle collisions on roads. Although Southeast Asia is a known biodiversity hotspot, majority of studies assessing effectiveness of such structures were conducted outside the region. Existing studies also tended to be non‐comparative and focused on crossing structures in silo. We addressed this gap by simultaneously surveying and comparing the usage frequency of mammals across three crossing types—culverts, roads and rope bridges—along a road surrounded by forests in Singapore. This allowed us to evaluate the preferences of mammals, assess usage patterns and investigate factors influencing the use of different crossing types. Using camera traps and closed‐circuit televisions, we documented 1133 independent crossing events across a 9‐month study period from March to November 2021. Fourteen mammal species were detected across all crossing types, with wild boar (Sus scrofa) being the most prevalent species (68.2%). Locally critically endangered species such as the Malayan porcupine (Hystrix brachyura), Sunda pangolin (Manis javanica), and Raffles' banded langur (Presbytis femoralis femoralis) were also recorded to use culverts, roads, and rope bridges for crossings, respectively. Although many species used multiple crossing types, most species had a preferred crossing method. Between culverts and roads, factors that influenced crossing preferences included group size for wild boars and time of day and presence of fences for other mammals. Even though such culverts were intended for drainage, they were still widely used by mammals. Overall, all three crossing methods were crucial in facilitating the movement of animals between habitats. Thus, a variety of infrastructure and measures to accommodate the diversity of wildlife moving across forest patches in a fragmented landscape is recommended.

In developed cities, bird communities are typically comprised of a few dominant invasive species that can cause considerable social and economic costs. While various studies advocate restricting anthropogenic food as a suitable management approach, a significant knowledge gap persists regarding how these species interact and respond to such an intervention. Here, we evaluate whether limiting a shared food resource may affect their abundances similarly and assess whether such limitations influence their niche dynamics. In Singapore, open food centres for people, colloquially known as hawker centres, serve as key food sources for three highly adapted urban birds: feral pigeons, Javan mynas and house crows. We counted these three species across 63 hawker centres and analysed their niche dynamics across different phases—before, during COVID‐19 social restrictions when dining‐in was prohibited, and during an enforcement phase mandating the return of crockery. We modelled their counts, diet niche widths and niche overlaps, considering predictors which include the sampling phases, food availability, structural characteristics of hawker centres and spatial attributes such as distance to public housing. During social restrictions, feral pigeon and Javan myna counts showed a significant decline, while the count proportions of the three species compared to each other remained relatively stable. Hawker centres closer to bridges and public housing, and those that structurally more open, attracted more birds. The niche widths of feral pigeons and Javan mynas significantly narrowed during social restrictions due to reduced food availability. However, their niche overlaps remained consistent across sampling phases, indicating resource partitioning strategies to cope with extreme food shortages—feral pigeons adapted by foraging more on grass verges outside, while Javan mynas frequented tray return stations. This resilience in maintaining species proportions and the absence of significant niche overlap suggested the existence of an ecological balance despite substantial reductions in available food. Synthesis and applications. Our study underscores the importance of controlling human‐provided food to collectively manage dominant urban bird commensals. Beyond the two social restriction phases, curbing the availability of anthropogenic food through enforcement also kept nuisance birds away, validating a cost‐effective approach in reducing their counts.

The illegal online trade in wildlife has increased significantly over the last 2 decades. Applying a systematic survey approach, we examined the online trade in elephant ivory before and after the implementation of a domestic trade ban in Singapore, to understand the forms of elephant ivory offered for sale, the e-commerce sites used and the effect of the domestic trade ban. Using elephant ivory and lookalikes in form, shape and colour as proxies for elephant ivory, we found that most of the online listings consisted of bird cages and related accessories such as bird feeding cups and ornaments used to adorn them. After the domestic trade ban in elephant ivory was implemented on 1 September 2021, a 76% drop in total listings was observed. Causal impact analysis indicated a strong causal effect of the domestic trade ban, resulting in an 83% drop in the mean number of new listings found weekly relative to the predicted counterfactual market response based on a Bayesian structural time-series model in the absence of the ban. E-commerce sites play an important role in combatting illegal wildlife trade online by removing flagged listings and sending notifications to raise awareness of the ban. We found textual descriptions of products to be more effective for preliminary differentiation of legal and potentially illegal listings compared to the detection of Schreger lines in images, although this remains a significant challenge for law enforcement. Our findings can inform future efforts to develop automated detection methods for elephant ivory in online markets.

The feral pigeon (Columba livia) is a globally commensal bird that can cause dis‐amenities such as soiling and is a potential vector of various diseases. Aside to limiting food as a management strategy, reducing the availability of roosting and nesting sites can help regulate feral pigeon populations. Despite their prevalence, current knowledge of their roosting and nesting preferences is lacking. Feral pigeons commonly use railway viaduct expansion gaps in Singapore for roosting and nesting. These gaps provided an ideal experimental platform to examine feral pigeon roost and nest site selection while controlling for differing cavity sizes which can significantly affect their reproductive success and site selection decisions. We also conducted an in‐situ experiment to test the efficacy of nest removal as a management option. Our nationwide surveys of 80.3 km of railway viaducts and 6048 gaps revealed that feral pigeon day roosting and nesting preferences are influenced by structural height and more importantly, their proximity to human food sources. There was a significantly higher probability of feral pigeon roosting in a gap if it had more pigeon feeding incidences in its vicinity and was higher. The probability of feral pigeon nesting in gap was higher if it was closer to a railway station, lower and further from water bodies. In our field experiment, we did not find any significant differences in the proportions of the abundances of feral pigeon to other urban commensal bird species at the gaps before and after nests were removed. Overall, our results suggest that a concerted effort to reduce anthropogenic food availability to feral pigeons is central in limiting their reproductive success and controlling their population.