The main difference between atlasing and normal birding is the focus on observing and reporting bird behaviors that indicate attempted breeding. Atlasing demands paying attention to the behaviors of individual birds. Once you observe a breeding behavior, you should add the breeding code that describes the behavior to your eBird checklist. Breeding behaviors are divided into four categories of breeding evidence: Observed, Possible, Probable, and Confirmed. There are multiple codes in each category, which are explained below.
Here are a couple points to remember when applying breeding codes.
Additional materials are provided to help you determine when a species is likely to be breeding and which codes are appropriate to use for each species. If you are in doubt about which code to use, please describe the behavior(s) you observed in the comments field for that species in your eBird checklist. You may also wish to contact your regional coordinator or pose the question on the Facebook Discussion Group.
Observed (no code) – Species present but without evidence of breeding and outside of its breeding season or suitable nesting habitat. No code is required. Any bird you enter on your eBird checklist without a breeding code will automatically be considered Observed. We ask that you submit complete checklists by reporting all species you observe; thus, most checklists will contain a mix of Observed species and species with higher level breeding codes.
F Flyover – Birds flying high overhead or in direct flight. This is not a breeding code, but can be a useful behavioral distinction. Tree Swallows foraging for insects are not considered a flyover because they are not in direct flight. Please see this page for more detail.
H In Appropriate Habitat -Adult in suitable nesting habitat during its breeding season. Avoid using this code if the bird in question may still be a migrant or wintering. Also avoid using this code for resident birds outside their breeding season.
S Singing Male – Singing male present in suitable nesting habitat during its breeding season. This code is also used for non-songbirds giving their primary vocalization during the breeding season, such as woodpecker drumming, owl calls, rail vocalizations, and woodcock peenting. If in doubt, refer to the Acceptable Codes Chart. In some species, both males and females sing (e.g., Northern Cardinal, Bicknell’s Thrush). You can still use this code for these species if the bird is in suitable habitat during the breeding season as song indicates the bird is getting ready to breed. If a bird is heard singing at the same place on a second trip during the breeding season, it may qualify as S7.
S7 Singing Male Present 7+ Days – Singing male present at same location on at least two occasions 7 or more days apart. Do not use if you observed the species singing a week earlier elsewhere in your block. This behavior presumes a permanent territory. This code should only be used if the initial observation was made after migration ceased. Observations must be made within the same breeding season; observations from different years do not apply.
M Multiple (7+) Singing Males – Multiple (7 or more) singing or territorial birds of a species detected within a block at clearly different locations within a single breeding season. If you are submitting separate checklists for different locations and habitats in your block (recommended) and you don’t have all 7 birds on a single checklist, use this code on the checklist where you reach a total of 7 birds and make a note in the comment field that you are including birds from other checklists in the block.
P Pair in Suitable Habitat – Pair observed in suitable nesting habitat during the breeding season. Only use this code when you are fairly certain that a mated pair of birds has been observed. Look for behavioral cues to determine if you have a male-female pair, particularly in species where males and females look the same.
T Territorial Defense – Permanent territory presumed through defense of breeding territory by fighting or chasing. While this is generally used for individuals of the same species, an interaction between members of different species may fall under this code when it appears to be territorial defense. Also see “A – Agitated Behavior.” Because territoriality involves the defense of a fixed area, it may be useful to map locations of individuals to determine if they are defending the same general area when surveying the block on future visits.
C Courtship, Display or Copulation – Courtship behavior or copulation between a male and a female. Courtship behavior includes transfer of food, displays, and grooming between a pair of birds.
N Visiting Probable Nest Site – Repeated visits to a probable nest site. This is especially useful for cavity nesters or for a shrub-nesting species that flies into the same thicket and disappears on several occasions.
A Agitated Behavior – Agitated behavior or anxiety calls from adults indicating a nest site or young in the vicinity. This code refers to a stronger reaction to intruders than those exhibited by “T – Territorial Defense,” usually against brood parasites, nest predators, and humans. Do not use this code for agitation induced by “pishing” or playing recordings. This code also excludes mobbing behavior that species engage in year-round (e.g., mobbing an owl).
B Wren/Woodpecker Nest Building – Nest-building by wrens or excavation of cavities by woodpeckers. Wrens may build “dummy” nests before the female selects a nest. Woodpeckers often drill holes for roosting.
PE Physiological Evidence – Physiological evidence of breeding based on a bird in the hand. This code is used primarily by bird banders and includes evidence such as a highly vascularized swollen incubation (brood) patch, cloacal protuberance, or an egg in the oviduct.
CN Carrying Nesting Material – Adult carrying nesting material to an unseen nest, such as sticks, grass, mud, and cobwebs. For raptors, be sure the material is not simply incidental to prey capture/transport. For wrens, use B.
NB Nest Building – Nest-building observed at the actual nest site, excluding wrens and woodpeckers.
DD Distraction Display – Distraction displays and injury feigning in attempt to draw intruder away from nest or young.
UN Used Nest – Used nest found, but no adult birds seen nearby. Use only if the nest was used during the Atlas period and you are certain of the species (i.e., the nest is inactive). Add comments detailing how you identified the nest. Do not collect the nest, but do take a photograph if possible. Enter ‘0’ if no individuals of that species are observed during your visit.
ON Occupied Nest – Occupied nest indicated by adult sitting in nest in incubating position, adult entering nest site and remaining, or exchange of incubation duties by the pair. This code is useful for nests high in trees, on cliffs, and in chimneys where the contents of the nest and incubating or brooding adult cannot be seen.
FL Recently Fledged young – Recently fledged or downy young still dependent upon adults and presumed incapable of extended flights from nest site. Look for retained downy feathers, a yellow gape, a short tail (shorter than the wings), clumsy flight and landings, and a bird incapable of feeding itself. Beware of family groups late in the breeding season which may still be interacting but are far from the breeding location. Young cowbirds begging for food confirm both the cowbird and the host species. If you find a dead fledgling and don’t see an adult of the same species, use a count of ‘0’ and enter the FL code.
CF Carrying Food -Adult carrying food for young or incubating partner. This code should not be used for corvids, raptors, terns, and certain other species that regularly carry food for courtship, caching, or other purposes. One of the best signs to look for is the repeated carrying of food in the same direction.
FY Feeding Young – Adult feeding young that have left the nest but are not yet flying and independent. This code should not be used for species that may move many miles from the nest site, such as raptors and terns. Use the NY code for nestlings being fed by an adult.
FS Carrying Fecal Sac – Adult carrying fecal sac or egg shell fragments. Many passerine adults keep their nests clean by carrying membranous, white fecal sacs and broken eggshells away from the nest. Note that only songbirds and woodpeckers produce fecal sacs and this code should only be applied to these groups of species.
NE Nest with Eggs – Nest with eggs. Be careful not to disturb the vicinity of the nest. Confirm the species by waiting at a distance until adult returns. If no birds are seen, use the UN code. If a cowbird egg is found in the nest, use code NE for both the cowbird and the host species; if no individual cowbirds were seen that day, then enter a “0” in the Brown-headed Cowbird number field during data entry.
NY Nest with Young – Nest with young seen or heard. Keep your distance so nestlings are not prematurely flushed from the nest. Include the nestlings in your species count. Presence of cowbird young confirms both the cowbird and the host species.