Journal Article

Abundance and Projected Control of Invasive House Crows in Singapore

Sodhi, Navjot S., Brook, Barry W., Malcolm C. K. Soh, Lim, Haw Chuan

2003

Overview

The Indian house crow (Corvus splendens) has successfully invaded tropical and subtropical regions well beyond its native range, reaching pest proportions in many areas. The invasive population of house crows in Singapore (Southeast Asia) has increased at least 30-fold since 1985 and now numbers in excess of 130,000 birds. To understand the population ecology and behavior of the house crow in Singapore, we undertook regular population size and roost surveys, dissections of birds shot (to provide age structure and breeding status), detailed nestsite observations, and monitoring of coastal dispersal. Using a discrete-time, density-dependent population model to synthesize this information, we demonstrated that at least 41,000 crows will need to be culled in the first year of a control program, and equivalent effort committed each year thereafter, to be confident of suppressing the Singapore population from its 2001 density of 190 birds/km2to the management target of <10 birds/km2within a 10-year period. This figure drops to 32,000 if culling is combined with other management strategies such as resource limitation and nest destruction. Complete eradication of the house crow from Singapore may be an unrealistic goal due to potential difficulties in detecting crows at low population densities and influx of migrants from neighboring Malaysia. Our study has implications for pest-bird management in other cities in Asia, Africa, and the Middle East, and presents a surrogate population-dynamics management tool for use in regions where the house crow has become established as a pest species, but where limited local field data is available.

• Publisher: The Wildlife Society,Wildlife Society,Blackwell Publishing Ltd
• Subject: Animal behavior / Animal populations / Animal, plant and microbial ecology / Applied ecology / Biological and medical sciences / Bird nesting / Bird pests / Birds / Breeding / Breeding status / Conservation, protection and management of environment and wildlife / Corvus splendens / Crows / Culling / Environmental monitoring / Fundamental and applied biological sciences. Psychology / Invasive species / Parks, reserves, wildlife conservation. Endangered species: population survey and restocking / Pest control / Pests / Phytopathology. Animal pests. Plant and forest protection / Population density / Population ecology / Population estimates / Population number / Population size / Vertebrates / Wildlife management