When should you add breeding codes to your checklist? Always!
Report behaviors you see in the blocks where you see them. If you aren’t sure, be conservative and add notes. Don’t overthink it, just do your best and use common sense.
When you’re out atlasing, you should always enter the highest breeding code observed for each species during that checklist. You should use breeding codes every time you observe breeding behavior, whether it’s peak breeding season or not.
The ‘highest’ code is the furthest down the list of breeding codes as displayed during data entry. The further down the list, the stronger the breeding evidence. By reporting the highest code each time you observe breeding behavior, you’re collecting valuable information about not just where birds breed, but also when birds breed. Your data help us understand breeding phenology or the timing of when each species breeds.
This graphic from the Wisconsin BBA shows the value of reporting behaviors throughout the season. You can see how birds are primarily building nests (CN, NB) in May-June, and then feeding young (CF, FY) later in June and into July. This information is really valuable to understand populations throughout the breeding cycle.
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 can also contact your regional coordinator or pose the question on the NY BBA III Facebook Discussion Group.