How this list is made

The species lists

Every species list comes from iNaturalist, where naturalists upload photographed sightings and the community identifies them. For each hike, a script drops search circles of 3 km radius along the route, one and a half radii apart, and asks iNaturalist for every animal recorded inside each circle. Long trails are sampled at up to 60 points along their length.

The survey keeps only records that are:

• research grade, meaning the community agrees on the identification;
• wild, not captive or cultivated;
• at their true location. Records whose coordinates are obscured to protect a sensitive species are left out, because their pin could be 20 km away;
• located to within the size of a search circle.

Subspecies are counted as their species. The lists keep the species in the Tracks catalogue — birds, mammals, reptiles, amphibians and fish — with the same rarity tiers as the app. Plants, insects and fungi are not listed yet. A species missing from a list may simply not have been recorded there yet: the busiest routes have the longest lists.

“Observations” counts the records in the survey circles. Neighbouring circles overlap, so on long routes treat it as a measure of how often a species is recorded, not an exact number of sightings. “Along route” says at how many of the route's search points a species turned up: one seen at most points lines the whole trail.