Hong Kong is using AI to track rats with thermal cameras, mapping when and where they appear. The system gives officials a new surveillance tool, but its “rodent absence rate” measures what cameras catch, not whether a district is rat-free.
Watch Desk analysis
What happened
The South China Morning Post reports that Hong Kong’s Food and Environmental Hygiene Department takes thermal images every two minutes from 7pm to 7am, over three consecutive nights every six months. The AI detects rats by their heat signatures, counts appearances, identifies peak activity hours and maps dispersal routes. Officials use those results to calculate an absence rate: the share of images in which no rodent was detected.
The report says 87,105 live or dead rodents were caught or collected in the first half of 2026. The annual total rose from 37,169 in 2016 to 157,182 in 2025. Yet absence rates exceeded 90 per cent in all 18 districts in the second half of last year.
Why it matters
Those figures measure different things. A high absence rate means few rats appeared in the snapshots taken at monitored locations and times. It does not establish what is happening outside the camera network, during daylight or between surveys. Urban ecologist Michael H. Parsons told the paper that rats may simply have shifted to areas without surveillance; he suggested daytime sightings over several days as another way to assess the problem.
The cameras can help officials spot activity patterns and adjust placements using complaints, inspections and catch figures. But mapping is not pest control on its own. The report also cites food waste and illegal dumping as contributors, while broken concrete and sewage pipes can give rats routes into public spaces. Better detection helps most when it leads to practical fixes.
Our read
This is a useful, specific AI deployment, not a magic rat-removal button. The technology can make a city’s response more targeted, but the headline metric needs its limits attached. If the system counts only what it sees, the question is whether officials also measure what residents experience and whether infestations stay gone.
What to watch
- Whether camera locations change in response to verified complaints and new hotspots.
- Whether officials publish daytime sightings or other measures alongside absence rates.
- Whether targeted surveillance is matched by action on food waste, dumping and damaged infrastructure.
Discussion spark: Should Hong Kong judge its AI rat-surveillance system by the patterns its cameras detect, or by whether residents see fewer rats?
Sources and evidence
- Deep Dive: Hong Kong turns to AI to tackle rat problem – South China Morning Post (11 October 2026, 14:45 UTC)
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