The Verde River Watershed is home to one of the rarest forests on Earth, the Cottonwood-Gooding Willow Gallery. Formed by the connection between the river and its desert surroundings, these forests, when healthy, support an incredible diversity of bird species. To measure riparian forest health, we compared the current number of bird species in a region to a list of species expected to nest in the riparian area of the region.
How is it scored?
A total of 87 unique bird species that nest in the riparian forests of the Verde River Watershed were identified by the Arizona Game and Fish Department's Element Occurrence database and the Arizona Breeding Bird Atlas. Combined, these databases provide what we called a baseline list of bird presence for each watershed zone. To compile data for riparian birds observed in the past two years, we used observations documented in the citizen sicence app eBrid. The final calculation for the Riparian Bird indicator was the fraction of species that were observed by citizen scientists over the past two years.
The Riparian Bird methodology changed slightly between 2020 and 2025. The main changes involved updating the taxonomy to the most recently accepted taxonomy for the species of interest, removing sensitive species from the species list (as exact locations were unavailable from eBird), and correcting errors in the breeding season for some species. The removal of sensitive species for which eBird locations were unavailable resulted in a slightly smaller list of species. Given that in 2020, the species that were removed would have shown no occurrences, their removal in 2025 may explain the slight increase in scores for riparian birds (there was a higher proportion of species that were seen within each watershed region).