Keeping Watch

The Florida Scrub-Jay is a species so inextricably bound to its habitat that it’s right there in the name. The intelligent and inquisitive corvid is highly social, and extended family groups act as the connective tissue that ensures the future of the species: Young from breeding seasons past stay local to help their parents raise the next brood.

When younger scrub-jays disperse and claim their own breeding territories, they don’t travel far from where they hatched, and they seem to have an aversion to crossing any areas that aren’t the scrub oak habitat for which they are named. Increased development has created disconnected patches of scrub oak, meaning these socially connected jays, already given to remaining close to home, are adrift on ever-shrinking islands and at serious risk of extinction.

As goes the Florida Scrub, so goes the Florida Scrub-Jay.

“We saw a need for a system that could tell us which habitats the most endangered birds are using and understand what threats those places and birds are up against,” said Michael J. Parr, ABC President.

“Birds relate to habitats, and habitats relate to birds,” explained Wiedenfeld. “Birds are very visible and easy to identify, more so than plants, insects, or mammals. They can be a useful mechanism to get people to understand what habitat they’re looking at.”

For the new Habitats WatchList, Campbell, Chaon, Parr, Wiedenfeld, and ABC partner NatureServe used vegetation and assemblages of bird communities to help identify discrete differences between habitat types, with NatureServe providing vegetation classification expertise and mapping. While some habitats are easily distinguished from others — Florida Scrub and Jack Pine Forests, for example — others are more difficult to define. Bird communities can be the factors that create the boundaries. Early Successional Temperate Forest and Nearctic Temperate Deciduous Forest may even have many of the same plants, but they don’t share the same feathered friends.

Birds are both a defining characteristic of habitats in this model and a metric to be measured. The presence, number, and conservation status of Indicator Species in a given habitat are key factors. The higher the number of Indicator Species (specialist bird species found only in one or very few similar habitats), the greater the conservation risk to that bird habitat.

Other criteria include the extent of the habitat and the amount of habitat that is currently protected. In both cases, the smaller the size, the higher the Threat Score. Parr and Wiedenfeld drew on analytical maps from NatureServe to develop a scoring system for three additional factors contributing to a habitat’s overall Threat Score. They included the condition of the landscape, assessed by NatureServe based on characteristics like the presence of invasive species and alterations to natural hydrology.

The final factors contributing to the ranking system take a longer view of a habitat’s vulnerability. The WatchList incorporates scores for the likelihood that the habitat in question will undergo conversion for agriculture, development, or other purposes. It also draws on NatureServe’s Climate Change Vulnerability Index, which models climate change-related impacts, assessing a habitat’s sensitivity to anticipated changes, its capacity for resilience and adaptation, and its expected exposure to climate stressors.

Scores for these seven criteria are weighted, and their sum can range from 10 to 100. The higher the number, the more threatened that habitat — and the birdlife it supports.

Of over one hundred habitats across the United States (including Hawaiʻi and Alaska) and Canada assessed, 13 comprise the Red WatchList, with Threat Scores of 68 or higher out of 100. Sixteen additional habitats with scores between 67 and 62 make up the Yellow WatchList — the second tier of threatened habitats.

Some results were fairly predictable. Conservationists have worried about some of the Red WatchList’s most highly threatened habitats — places like coastal marshes, Hawaiʻi’s unique wetlands and forests, grasslands and prairies — for decades, and these are indeed well represented on the WatchList. The habitats on the list also happen to be places where some of the most endangered birds in the United States and Canada are found.

The Gulf Coast Salt Marsh habitat, home to the secretive and scarce Black Rail and the winter destination for dozens of the world’s remaining Endangered Whooping Cranes, ranks perilously high — 74 out of 100 — for climate and conversion threats. Its saving grace might be its score for protection: It scored low, a 1, indicating a high proportion of habitat protected. The Salt Marsh habitat on the Atlantic Coast, the only habitat used by the Endangered Saltmarsh Sparrow, a Partners in Flight Red Watch List species, is similarly situated: existential threats offset by some protections.

Likewise, it wasn’t a shock to see Florida Scrub, the exclusive home of the Florida Scrub-Jay, on the Yellow WatchList. Fewer than 10,000 scrubjays hang on in habitat that covers a small area and is in poor condition, at grave risk of conversion, and severely lacking adequate protection.

The analysis did yield some surprises, however.

“The presence of Nearctic Temperate Deciduous Forest on the Red WatchList was unexpected. It’s a habitat that is very extensive — that’s what occurs in my backyard,” said Wiedenfeld. These expansive, oak- and hickory-dominant closed-canopy forests cover much of the eastern United States and Canada, south of the boreal forest. Many large tracts of this forest type are still intact, providing habitat for high-canopy dwellers like the Cerulean Warbler and well-developed mid- and understories where the Wood Thrush is commonly found. (Both birds are on Partners in Flight’s Yellow Watch List.) This habitat is threatened, though, because much of it is in poor condition, and much of it is threatened with conversion to other habitat types.

Another surprise was the ranking of the Prairie Potholes, a type of prairie created in the wake of retreating glaciers that left behind a scarred landscape marked by permanent and ephemeral “potholes” that fill with water in the spring. This prairie type on the northern Great Plains hosts American Bitterns, Blue-winged Teals, Piping Plovers, Willets, Yellow-headed Blackbirds, and scores of other migratory species.

Over the past two centuries, many Prairie Pothole wetlands have been lost to agricultural development, and the surrounding grassland matrix is even more imperiled. Loss of wetlands to development has slowed, though it remains a threat. The most serious looming threat is climate change, as drought could lead to the loss of many more wetlands.

“The Prairie Potholes are known to be an important region, and there has been a lot of conservation effort there, but still, it’s showing up on the Red WatchList,” said Wiedenfeld.

“The 2025 State of the Birds Report reveals that we’re still losing birds at an alarming rate,” said Parr. “ABC developed the Habitats WatchList to help guide our conservation efforts in places like the Shortgrass Prairie in the Great Plains, where we’ve been working for many years. This new tool will aid in further strategizing positive outcomes for the species that need it most.”

While the Habitats WatchList informs ABC’s work with imperiled species such as the Lesser Prairie-Chicken, Mountain Plover, and Thick-billed Longspur, all residents of the highly threatened Shortgrass Prairie, the WatchList has much broader applications.

“Our hope is that other conservation practitioners will use the Habitats WatchList, from someone managing small state parks who is interested in knowing more about the habitats they’re stewarding and which ones are most threatened, to state wildlife managers and threatened species researchers working at a larger scale planning land management or conservation activities,” said Wiedenfeld.

An accompanying GIS map tool allows anyone to search by habitat or find their location and learn about the habitat around them. Beyond serving as a resource for conservation planners, biologists, and land managers, the Habitats WatchList can also be a tool for birders and backyard naturalists, providing a new way to experience the habitats around them with a new level of detail and granularity.

“You can use the Habitats WatchList map to help you identify where you are, understand what birds you might expect to see, and, crucially, to know how important the habitat is,” said Wiedenfeld. The GIS map has information about the composition of the habitat itself, the bird species that use it, and the threats it faces. The Threat Scores for all habitats are available, so any user can learn about the risk factors at play.

By making a tool like the Habitats WatchList available, and making it easy for anyone to learn about the threats habitats are facing, Wiedenfeld hopes birders and naturalists might start asking questions about the habitats they’re in: “Is this habitat in good condition? Does it need protection? What can I do to support this habitat if I want to continue to see those birds?”