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The Finch Index 2026 · explainer

What the spring count tells us about the birds in your park

Every spring, volunteers in twelve city parks walk the same routes and write down the songbirds they hear and see. This year's Finch Index is the first full count since 2019, and it gives park officers a plain picture of what has changed on their own ground.

How the count works

Each transect is walked on four mornings between 1 April and 30 June, with observers recording passerine contacts in 50-metre bands either side of the line, and detectability corrected using a distance-sampling model fitted across sites.

Results are then compared with the 2019 survey, park by park, so that a good year in one place does not hide a poor year in another.

What changed

Across the twelve parks, greenfinch numbers fell by 14% and blackbirds held steady. Goldfinches did best, up 9% and now seen in every park on the list.