Work in progress—the treatment of Exotic species in the eBird database is currently being revised. The information below reflects updates made in August 2022. Additional updates are expected later this year; we indicate these anticipated changes below where possible. Watch the eBird homepage for more announcements.
TABLE OF CONTENTS
- What is an "Exotic" Species?
- eBird's Exotic Species Categories
- How are Exotic Species displayed in eBird?
- Frequently Asked Questions about eBird's Exotic Species Policy
- Additional Examples
What is an "Exotic" Species?
eBird considers an Exotic species to be any species that occurs somewhere as a direct result of transportation by humans.
This does NOT include situations where a species' distribution has spread due to human activities, including habitat alteration, such as:
Brown-headed Cowbird (Molothrus ater) which has spread both east and west in North America with increases in agriculture.
Eurasian Collared-Dove (Streptopelia decaocto) in western Europe, which spread westward over the last century.
The spread of open-country species into Amazonia [e.g., Crested Caracara (Caracara plancus), Guira Cuckoo (Guira guira)] and into the isthmus of Panama [e.g., Southern Lapwing (Vanellus chilensis), Cattle Tyrant (Machetornis rixosa)], as forests have been cleared in recent decades.
Why do Exotic Species Matter?
As of August 2022, at least 4.8% of observations in eBird's 1.27 billion bird database involved records of exotic species, indicating that they are a major part of the modern avifauna. Studying how these birds interact with ecosystems is important for conservation, management, and science. Population changes in exotic species can occur at a much faster rate than changes in native species, and eBird provides powerful opportunities for monitoring these changes. Because correctly tallying personal birding lists with respect to exotic species affects how the birding community reports these birds, eBird has developed a revised process and policy to encourage monitoring and facilitate tracking of exotic birds. The eBird Exotic Species Policy supports these goals by incentivizing data collection and ensuring high quality data on exotic species while also supporting the expectations of birders.
Some exotic species are very harmful to native bird populations, competing with them for nest holes and food, aggressively driving them away, or even preying on them. In other cases exotics are more benign, occupying vacant urban niches within ecosystems dominated by composed of non-native vegetation that was already fairly devoid of native species. In an ironic twist and conservation conundrum, some of the most robust free-flying populations of certain species are exotic populations (e.g., United States Red-crowned Parrots Amazona viridigenalis in Los Angeles, California, Brownsville, Texas, and Miami, Florida) while the native populations remain under threat of extirpation via the very cage bird trade that spawned these introduced populations.
eBird's Exotic Species Categories
All observations of exotic species in eBird are assigned to one of three categories which reflect their breeding status and extent of establishment. How a species is categorized may change over time, as non-native populations become established or decline.
Below are examples of Naturalized species in eBird:
About 100 European Starlings (Sturnus vulgaris), also known as Common Starlings, were introduced to New York City in ~1890; throughout the following century, starlings spread across all 50 states, south through Latin America and north to Alaska, and are now one of the most abundant birds on the continent.
Similarly, Canada Goose (Branta canadensis) has been widely released in Europe and breeds in most Western European countries, blurring the question of whether and how much natural vagrancy occurs. Given how widely the population is established, all Canada Goose reports in Europe are treated as Naturalized, although records that suggest trans-Atlantic vagrancy could potentially be recoded as native.
Lesser Redpoll (Acanthis cabaret) was introduced to New Zealand in the 1860's and is now among the more abundant passerines there.
Provisional is often used for species that are established (i.e., occurring in substantial numbers in the wild for many years) but have not yet been declared Naturalized by a local ornithological authority. Provisional species count towards your eBird life list and appear in all public outputs, including Alerts.
One example of a Provisional species in eBird—
Swinhoe's White-eye (Zosterops simplex) was introduced in Costa Mesa, Orange County, California in 2006 and has been spreading widely ever since. Many thousands occur in southern California now and the most intrepid birds have reached the Channel Islands, Baja California, and Santa Barbara. We expect Swinhoe's White-eye to be treated as Naturalized in California once the California Record's Committee's 15-year threshold passes in another year or two. Treating such species as Provisional helps to communicate their true status and prepare birders for their likely future treatment as Naturalized.
Records that could pertain to wild vagrants or to escapees may also appear as Provisional. For example:
In Europe, certain species that could plausibly represent vagrants but also have a known history of being kept in captivity are similarly treated as Provisional, such as Red-headed Bunting ( Emberiza bruniceps ) in the United Kingdom and Falcated Duck (Mareca falcata) in Finland.
Black-backed Oriole (Icterus abeillei) is an interesting case. A Pennsylvania record was accepted as a wild vagrant by the Pennsylvania Records Committee, but the same individual (identified by distinctive aspects of plumage) wandered to Massachusetts and probably Connecticut, where records committees in those states treat it on their "Provenance Uncertain" lists (and thus Provisional in eBird). California records of the species have also been treated as Provisional, given the possibility of escaped individuals accounting for those records.
Below are several examples of Escapee records in eBird:
A wide range of waterfowl and parrots occur semi-regularly as escapees, but some really surprising birds may be found too. A Long-tailed Mockingbird (Mimus longicaudatus) in King County, Washington, US, in June 2014 is one of the more unique outlier records and a reminder to consider escapees whenever you discover or chase a rare bird! Long-tailed Mockingbird is a species of western Ecuador and Peru that we don't think could occur as a vagrant so far from its native range, so transport in a cage or on a ship seems the only plausible explanation.
The same year that an apparently wild Steller's Sea-Eagle (Haliaeetus pelagicus) made news across North America, another Steller's Sea-Eagle escaped from the Pittsburgh Zoo in Pennsylvania; this individual would have been treated as an Escapee if it had been reported to eBird.
Red Avadavat (Amandava amandava) occurs occasionally in small numbers on Puerto Rico, and apparently breeds at least sometimes. They don't occur in sufficient numbers and don't have a stable enough breeding population from year to year to be considered Provisional.
Remember: please only report free-flying, unrestrained birds to eBird. Captive birds in zoos and wild bird parks, as well as free-roaming pets that return to houses and farms each night (such as peafowl and domestic chickens), should not be reported on eBird checklists. Checklists that report multiple captive species on one list may not be eligible for public display and scientific use.
Reintroductions of Native Species
One important exception to the three categories above are reintroductions of native species. When a species is released by humans into its former native range:
- Re-introduced populations will generally be considered native (i.e., not Naturalized) in areas where they are breeding in the wild, even if additional individuals are still being released from captive-breeding or relocation programs.
Populations are treated as Provisional when breeding efforts still are strongly supported by humans and the species is not yet successfully reestablished.
Vagrants or natural colonists from existing populations, or any bird that arrives under its own power, should carry the exotic category from its presumed region of origin. Thus, a stray Eurasian Collared-Dove (Streptopelia decaocto) that reaches northern Venezuela would be considered Naturalized if it was believed to originate without human assistance from Naturalized populations in the Caribbean.
There have long been accounts of seabirds (boobies, gulls, etc.) and landbirds found on ships and staying onboard for prolonged periods as the ships move towards their destination, with some birds riding all the way to port and covering distances that few or no wild individuals could have crossed under their own wing power.
Seabirds (e.g., gulls, albatrosses) should be treated as native when they intentionally follow vessels, especially fishing boats, without landing on them. Vagrants that are known or suspected to be "ship-assisted"—i.e., riding on the ship—should receive either Provisional or Escapee status:
Vagrant records of birds that are restrained, fed, or aided by humans onboard a ship should be treated as Escapees; this is like transporting a bird in a cage on an airplane or in a car.
When ship-riding birds are unrestrained and not fed, those records should be considered Provisional.
Ideally, observers would note such details in their species comments when reporting these observations.
How are Exotic Species displayed in eBird?
Exotic or introduced species are indicated in eBird by the following asterisk icons.
Tap any exotic icon on the eBird website for full Exotic Category definitions. For more information about these categories, see eBird's Exotic Species Categories (above).
Where do these icons appear?
eBird Exotics icons currently appear on observation lists, individual checklists, Hotspot and Regional explore pages, Illustrated Checklists and maps. They will soon appear on your life lists, target lists, bar charts, and Trip Reports.
Exotic species in eBird outputs
Exotic species icons may appear in two different places. For individual observations (a specific sighting by an observer at a specific place on a specific date), we display an Exotic Category as defined above. For regional summaries, which may draw on many observations, we display an Exotic Status, which represents the highest Exotic Category for any observation within the region. Therefore, if there is a single native record of Ruddy Shelduck along with hundreds of records treated as Escapee, the status will be native. If records are split between Provisional or Escapee, then the status displayed on explore pages will be Provisional.
Exotic species in the Escapee and Provisional categories appear in separate sections at the bottom of most eBird outputs such as hotspot and regional species lists (below Naturalized and native species). Provisional species are included in species totals, while Escapee species—similar to hybrids and non-species taxa—are un-numbered and do not count towards regional and hotspot species totals.
Exotic species designations are also provided in raw eBird data downloads in the ‘Exotic Code' column.
Exotic Species on your eBird Life List
eBird Life List adjustments are in progress. Exotic species will soon appear on your eBird Life List the same way they appear on regional and hotspot explore pages, with Escapee and Provisional species grouped in separate sections below Naturalized and native species.
Frequently Asked Questions about eBird's Exotic Species Policy
How are eBird Exotic Categories assigned?
Exotics categories are assigned and refined by regional volunteer reviewers in collaboration with eBird Central based on local knowledge, published articles, and birding records committee decisions, where available. As of August 2022, the fine-tuning process of assigning accurate eBird Exotic Categories to individual records remains a work-in-progress and is expected to take some time.
What if I only want to "count" native and Naturalized species?
Some birding groups consider only native and Naturalized populations to be ‘countable' for regional records and life lists, while eBird also includes Provisional species in official totals.
If you value your native and Naturalized total, or report listing totals to a group that observes listing rules different from eBird, don't worry—eBird makes it easy to find that number. With updates coming later this year, Provisional species (species that are established but not yet considered Naturalized) will be grouped below fully ‘countable' Naturalized and native species on your eBird Life List so it will be very easy to see your eBird listing totals with and without Provisional species.
Report ALL free-flying species—including Provisional and Escapee species—whenever you find them!
It is important to remember that many Provisional species are well-established in the wild and have great potential to become Naturalized in the future. In fact, some Provisional species might already meet the criteria for Naturalized right now, and are simply pending formal Records Committee acceptance.
eBird is an incredibly valuable tool for tracking the establishment of introduced species. eBird can monitor the establishment/spread of exotic populations on a faster timeframe than most ornithological societies operate.
By reporting Provisional and Escapee species to eBird you help the scientific and birding communities more accurately determine when and which species have reached the point that they can be considered fully Naturalized.
What about ‘Domestic type' taxa?
eBird has separate ‘domestic type' taxa for 15 species. When you see these in eBird they will always have an Exotic Code, which can range from Escapee (most often) to Naturalized (for some species) depending on their level of establishment.
Importantly, domestic type taxa should be thought of as taxonomic entities—sort of like subspecies. They are a sub-population of the parent species with a unique and specific evolutionary history and appearance. Many domestic types are larger and have more variable plumage (often white, black, or mottled) compared to their parent species. In most cases the domestic types don't form self-sustaining populations and don't occur near the native range of the parent species, but there are notable exceptions (Graylag Goose, Mallard, Muscovy Duck, and Feral Pigeon have the most overlap in the range of native and domestic type forms).
When reporting to eBird, please report wild-type birds as the parent species and use "domestic type" for individuals that show clear signs of domestication. These two types are generally identifiable in the field, so identify them as you would any other species, but also take note of their behavior and habitat.
For example, if you see two dark-plumaged Muscovy Ducks along a wooded river in Central or South America that flush on your approach, please report those as Muscovy Duck (as they meet the description of wild type, native populations); if you later see some mottled white-and-black Muscovy Ducks with extra large, red warty faces at a park, those are identifiable as "Muscovy Duck (Domestic type)", so please report them that way.
For Rock Pigeons in parts of Europe, Asia and northern Africa, it can be hard to separate wild type from Feral Pigeon types. We encourage specific reporting of Rock Pigeon (wild type) only in Europe, Asia, and northern Africa and only when you are certain; otherwise, using the generic Rock Pigeon is the best option. In places where there are only Feral Pigeons, such as North and South America or Oceania, please only ever use "Rock Pigeon (Feral Pigeon)".
See here for more information on domestic type taxa in eBird.
Species distributions are complex and dynamic. eBird's Exotic Species codes are designated based on expert knowledge and input from regional partners. Below are some additional examples of how eBird's Exotic species codes are currently applied to introduced species in regions throughout the world.
This Paddyfield Pipit—a mostly resident species typically found in South and Southeast Asia—was observed in Cornwall, United Kingdom in the fall of 2019. While similar species of pipit have been known to occur as vagrants in Britain, Paddyfield Pipits also have a history of being kept in captivity. After careful consideration, the British Ornithologists' Union Records Committee was unable to determine whether the Paddyfield Pipit in Cornwall was of captive or wild origin (see Bird Guides discussion), and all reports of this species in the UK are treated as Provisional. Similar cases of rarity records of uncertain provenance may be shown as Provisional.
No. 492 (AKA "Pink Floyd") the Greater Flamingo–a species native to Eurasia and Africa–escaped from a Kansas zoo in 2005 and is now regularly spotted on the Texas coast. Despite widespread distribution, Greater Flamingos do not occur as vagrants in the United States; reports of "Pink Floyd" (along with free-roaming Greater Flamingos in Florida and California) are treated as Escapee.
Bar-headed Goose, Mandarin Duck, and Wood Duck are just three examples of a wide range of striking waterfowl that are popular with waterfowl fanciers worldwide. They escape regularly and pepper the planet with Escapee records. eBird range maps for these species clearly indicate the native range (in purple) and all three species have some portions of their ranges treated as Provisional or Naturalized. Explore the maps for Bar-headed Goose (map), Mandarin Duck (map), and Wood Duck (map) and try the Escapee toggle to show or hide grid cells that have only Escapee records; click points to see Exotic Status at a location.