Counting foxes without a total
When ecologist Priya Sen began counting foxes in Eastbridge, residents assumed she wanted a total. Local newspapers asked how many animals lived in the city, and councillors wanted to know whether the number was rising. Sen’s project used cameras, reported sightings and samples collected from parks, but its first result was a refusal: the methods could not produce one reliable city-wide figure.
41Cameras recorded places rather than populations. A fox that crossed three gardens might appear on three devices, while an animal living beside an unmonitored railway could remain invisible. Reports from residents were even less even. People noticed foxes after public discussion of foxes, and the same animal became several sightings as it moved along a street.
42Instead of abandoning the data, the team changed the question. They began mapping where different forms of evidence agreed, where they conflicted and which parts of the city produced almost no reports. This revealed not a population map but an observation map: a picture of fox activity entangled with human routines, lighting, property access and willingness to report.
43One apparent hotspot surrounded a late-night bakery. Camera images showed repeated visits, but genetic samples suggested that only two animals were involved. Another area produced many resident reports and no photographs because the cameras faced paths while the foxes moved along garden walls.
44These mismatches became useful when the council proposed sealed rubbish containers in several parks. The original plan targeted locations with the largest number of sightings. Sen argued that sightings reflected both fox behaviour and human visibility, so intervention should follow evidence of food access instead of public attention alone.
45The revised trial combined cameras aimed at bins, inspections of damaged containers and short interviews with maintenance staff. In one park, fox images fell after new lids were installed; in another, they remained stable because food came from nearby restaurants. The same equipment therefore had different effects within a few kilometres.
46At the end of the project, Sen still could not state how many foxes lived in Eastbridge. She could explain where particular interactions were likely, why some evidence appeared persuasive and how a management decision might move rather than remove a problem. The council received fewer dramatic numbers than it had requested, but a more useful account of what those numbers would have hidden. Volunteers were trained to describe where a camera faced and what blocked its view, not only whether a fox appeared. Those negative observations later explained why apparently comparable devices produced different patterns, turning routine maintenance records into part of the ecological evidence. The reporting protocol distinguished a camera that had recorded no fox from a camera whose battery, angle or vegetation made absence uninterpretable, preventing technical silence from being merged with ecological silence in the same empty cell.
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That answer disappointed people who equated scientific seriousness with a precise estimate. Sen argued that precision would be artificial because each method sampled a different relationship between animals, places and observers. Combining them did not automatically cancel their biases; it could merely conceal disagreement inside a larger number.
The team also tested thermal cameras borrowed from a university laboratory. They detected movement through vegetation more effectively at night, but the equipment was too expensive to leave unattended and produced images that volunteers found difficult to classify.
Maintenance workers altered the interpretation again. They knew which lids were routinely left open after events and which containers looked damaged because delivery vehicles struck them. Their practical knowledge converted a photograph of a fox beside a bin into a sequence of opportunities instead of proof of a permanent local concentration.
Seen together, the cases prevented the team from treating visibility as abundance. A place could look busy because a small number of foxes returned repeatedly, while another could appear empty because both cameras and residents watched the wrong routes. The contradictions described how observation worked.
The distinction mattered because the proposed policy was not intended to reduce fox numbers directly. It aimed to reduce access to predictable food, which required evidence about bins, collection schedules and nearby businesses rather than a ranking of neighbourhoods by public sightings.
This was not simply a technical limitation. The desire for a total assumed that the city contained a stable, bounded population, although foxes crossed municipal edges and changed routes as construction or food sources changed. The object being counted was partly created by the boundary of the question.
The bakery owner initially objected to being named in the report, fearing that customers would associate the business with poor hygiene. The final map therefore showed food sources by category rather than identifying individual premises, while inspectors retained the detailed locations for practical work.