eBird is a popular citizen science project created by the Cornell Lab of Ornithology which allows bird watchers to record and share their bird sightings. When submitting bird sightings to eBird, users have the option to include breeding codes which provide information about the breeding status of the birds observed.
What are breeding codes?
Breeding codes in eBird allow users to specify information related to breeding bird behavior and status. The breeding code indicates whether there is evidence of possible, probable, or confirmed breeding for the reported species. This helps provide valuable data to scientists studying avian breeding biology and phenology.
There are 7 breeding codes that can be used in eBird:
| Breeding Code | Meaning |
|---|---|
| ON | Observed, no breeding evidence |
| PY | Possible breeding |
| PR | Probable breeding |
| CO | Confirmed breeding |
| NB | Nest building by wrens, swallows, etc. |
| DD | Distraction display or injury feigning |
| UN | Used nest or egg shells found (occupied or laid within period of use) |
The most commonly used codes are ON, PY, PR, and CO. The ON code is used when birds are observed but there are no signs of breeding activity. PY, PR, and CO indicate increasing evidence of possible, probable, and confirmed breeding respectively.
When should you use breeding codes?
Breeding codes should be used whenever there are behavioral cues or physical evidence that indicate possible, probable, or confirmed breeding for the reported species. Here are some examples of when breeding codes would be appropriate:
- PY – Birds observed carrying nesting material, copulating, or investigating possible nest cavities.
- PR – Agitated behavior or alarm calls suggesting a nearby nest or young. Adults observed carrying food or fecal sacs.
- CO – Active nest found with eggs or young. Adults observed feeding nestlings.
- NB – Wrens building nests, swallows carrying mud for nest construction.
- DD – Birds feigning injury to distract from nest or young.
- UN – Used nests or eggshells from current breeding season found.
The ON code should be used if birds are observed but there is no indication of breeding activity. However, the lack of evidence does not preclude possible breeding, especially for cryptic, nocturnal, or secretive species.
Why are breeding codes useful?
Breeding codes provide valuable ancillary data for researchers studying avian breeding biology including:
- Phenology – First egg dates, onset of nesting period, etc.
- Productivity – Number of successful nests, fledglings, etc.
- Distribution – Expansion or contraction of breeding ranges.
- Trends – Change in breeding populations over time.
- Habitat – Associations between breeding success and habitat type.
Inclusion of breeding codes allows eBird data to be analyzed to look for changes and trends in breeding productivity and distribution over time. This information helps identify vulnerable populations, improve conservation efforts, and expand knowledge of bird breeding ecology.
How to enter breeding codes in eBird
Entering breeding codes in eBird is easy!
When reporting a bird sighting, simply:
- Check the “Add breeding code” box
- Select the appropriate breeding code from the dropdown menu
- Add any relevant notes about breeding evidence observed
Breeding codes can be entered when reporting complete bird checklists or individual bird sightings. The codes are displayed alongside the species on your lists and sightings. You can also filter eBird data by breeding code to analyze breeding records.
Examples of breeding codes in eBird
Possible Breeding
PY code – American Crow observed carrying sticks, possibly gathering nest material.
Probable Breeding
PR code – Western Scrub-Jay observed with food in bill, likely carrying to nestlings.
Confirmed Breeding
CO code – Found nest of Black-chinned Hummingbird with two eggs.
Nest Building
NB code – Barn Swallow observed repeatedly carrying mud back to nest site under eaves.
Distraction Display
DD code – Killdeer flapping and calling loudly, feigning injury to distract from nearby nest.
Conclusion
In summary, breeding codes allow birders to provide important details about avian breeding activity when submitting records to eBird. This contributes valuable data to our knowledge of bird distribution, productivity, trends, phenology, and conservation. The 7 breeding codes cover the range of breeding evidence from no indication (ON) to confirmed breeding (CO). Adding codes is simple when entering eBird checklists or reports. So next time you observe evidence of breeding behavior, be sure to make use of eBird’s breeding codes!
