Moth counts across the Dark Sky Park have fallen by 31% over five years of standardised trapping, in line with declines recorded nationally.
At one location, counts have risen by more than 900%.
The location is a toilet block with a security light that has been on every night since it was installed in 2022.
Why the rise is bad news
The concentration is not a population. It is an aggregation, drawn from the surrounding area, of insects that would otherwise be dispersed across several square kilometres doing the things moths do, which include pollinating a substantial share of night-flowering plants and forming the bulk of the diet of every bat in the district.
Moths at a light do not feed. They do not breed. Many circle until dawn and are then taken by birds, in what researchers describe as an ecological trap: a cue that reads as beneficial and is not.
“It is a very effective moth collector. It has been running for four years and nobody switched it on for that reason. It is there so that people can find a door.”
The survey coordinator
The awkward context
The facility exists because this newspaper, among others, has spent two years reporting that the north and south west need more toilets, which they emphatically do.
The point of this article is not that the block should not be there. It is that a £40 fitting choice made without anyone thinking about it has, in a designated Dark Sky Park, produced the largest single point source of ecological light impact in the district.
The counts
- Park-wide change over 5 years: down 31%
- At the lit facility: up over 900%
- Light in place since: 2022, on dusk to dawn
- Cost of a downward-shielded, warm-spectrum, motion-activated replacement: under £90
- Similar unshielded lights identified across the park: 34
An audit of the other thirty-four has been requested. The park authority has confirmed it will be considered at the next meeting, which is in October.
