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Singapore House Crows Kept Preferred Tree Species but Shifted Other Nest-site Choices

Wild house crow beside a nest in an urban structure
Research · Ecology

A 2026 study found that invasive house crows (Corvus splendens) in Singapore have changed some of their nest-site preferences over the past two decades as the city’s urban landscape and food management have changed.

Researchers surveyed 30 nest trees and 30 non-nest trees in 2022 and compared the results with a similar Singapore study from 2001. The overall proportions of the main nesting tree species had not changed significantly across the two decades. House crows continued to favour particular species, especially yellow flame (Peltophorum pterocarpum) and broad-leafed mahogany (Swietenia macrophylla), while raintrees and other species were used less often than expected.

Distance from buildings had a clear negative relationship with nest-site use in the newer models: nesting probability decreased as trees were farther from buildings. Greater distance from roads and a taller branch-free section of trunk were also positively associated with nesting, while wider branch angles showed a weaker positive relationship. The authors note that wider branch forks may give nests more structural support and stability.

Several factors that had been important in 2001, including crown size and density and distance to bin and food centres, no longer appeared among the strongest predictors. The authors suggest that improved containment of food waste and changes in Singapore’s urban bird community may have altered how crows choose nesting sites. They recommend continued food-waste management together with targeted nest removal, pruning and more varied urban tree planting.

Sources and image credit

  1. Leong, Y. X., Soh, M. C. K., Chia, S. J. M., Samsuri, A. N., Ng, Y. Z., & Er, K. B. H. (2026). Changes in nesting preferences of the invasive house crow (Corvus splendens) after two decades in Singapore’s evolving urban landscape. Frontiers in Ecology and Evolution, 14, 1784788. https://doi.org/10.3389/fevo.2026.1784788Primary open-access research report published 25 May 2026. The study surveyed 60 nesting and non-nesting trees and compared nest-site selection with a 2001 Singapore study.

Image: P. Jeganathan / Wikimedia Commons — wild house crow beside an urban nest at Egmore railway station, Chennai, India, 10 February 2017; representative image, not a bird from the Singapore study · CC BY-SA 4.0 · Source

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