Live/2024/Data & visualisation
Saltmarsh Atlas
Twenty-two years of local bird survey records turned into a migration atlas, made for the volunteers who collected the data rather than for researchers.
A local ornithology group had 22 years of paper and spreadsheet survey records in about nine incompatible formats. Saltmarsh Atlas is the cleaned dataset plus a set of views that let a volunteer find the species they personally count and see how its arrival dates have moved.
The unglamorous half
Most of the work was reconciliation: species naming conventions changed twice over the period, two observers used different site boundaries, and one year of records existed only as scanned notebooks. The Python pipeline is documented heavily because the group needs to keep running it without me.
Visualisation choices
- Arrival timing is shown as a ridgeline per species per decade, which reads more honestly than a trend line over sparse data.
- Counts are deliberately not normalised; observer effort varied and pretending otherwise would flatter the data.
- Every chart links back to the underlying rows, because the volunteers will and should check it.
Outcome
The dataset is now the group's reference copy, and two arrival-date shifts it surfaced were written up in their annual report.