Frequently Asked Questions


Breeding Codes


When should I use breeding codes?

You should use a breeding code whenever you see behavior that indicates the bird might be breeding, which generally depends on the time of year. Some breeding codes are strong evidence of breeding and can be used at any time of year, like code NE (nest with eggs). Other breeding codes are best used during a bird’s breeding season, like code P (pair in suitable habitat). You can use the Breeding Timeline to see when each species nests in Maryland and DC and when each species is overwintering or migrating. Avoid using weak codes like code H (in suitable habitat) or code S (singing in suitable habitat) during the species’ overwintering or migratory season.


When should the flyover code be used?

Code F (flyover) should be used when a bird is flying overhead and not using the habitat below it. You should not use it when a bird is just flying. As you can imagine, this can be quite subjective, so if in doubt it is better not to use the code. This code is primarily used to help develop habitat association models, so one way to think about it is whether you would expect to see that species in the habitat you are in. If you would not expect this—say, a Double-crested Cormorant flying over while you are in a forest—it may qualify for code F.


What does ‘suitable habitat’ refer to?

Suitable habitat is the general ecosystem that a species would be expected to nest in. If you see a Rock Pigeon in the city, you can give it code H (in suitable habitat); it does not need to be under a bridge near an appropriate nesting site to receive this code. This code, despite being one of the most frequently used codes, is one that requires some basic knowledge of what each species uses for nesting habitat. Year-round residents may be in suitable nesting habitat all year, so code H should not be used during their non-breeding, overwintering season. Suitable nesting habitat for migratory species is found within their breeding range, not along their migratory route.


What is considered singing?

While there is considerable overlap, there are two main categories of bird vocalizations: songs and calls. Songs are generally considered to be loud, often long and complex vocal displays of territorial birds. They are often important for courtship and maintaining pair bonds. Calls are considered to be short and simple vocalizations used to communicate, among other things, distress, warnings, flight, or to maintain flock cohesion. For atlasing purposes, don’t get hung up too much on technical definitions. Basically, if it sounds like a song, you can use code S (singing). You can also use code S for woodpecker drumming or other territorial sounds.


When should I use the S7 or M codes?

Code S7 (a bird singing in the same place for 7+ days during its breeding season) should be used to describe a bird that you are reasonably sure is the same individual because it describes a bird that is likely to have a nesting territory. Some birds maintain winter territories, and some birds sing during migration, so it’s important to use this code at the right time of year. For example, a Song Sparrow singing in February may just be overwintering there, so using code S7 for that observation would not be a good choice.

Code M (7+ birds singing during their breeding season) is a good code to use for common birds. Similar to code S7, it should only be used during a species’ breeding season. If you hear seven or more birds singing in the same day and in the same block and it is during their nesting season, you can use code M.


How do I know when I see a pair and not just two birds together?

Knowing the difference between two birds that are nesting together (a pair) and two birds that are just close to each other can be difficult. First, consider time of year. Most birds do not maintain pair bonds during the winter, so using code P (pair in suitable habitat) outside of a bird’s breeding season is not usually a good choice. Next, try to determine their sex and age; if they are juveniles or the same sex, you can safely rule out code P. If you cannot determine sex or age, you will have to rely more heavily on their behavior. A pair should be two birds that are on their own and not part of a larger flock and are generally moving together or perched close together. If you are watching a species that is normally solitary, two individuals close together is generally enough indication that they are a pair. If you are unsure about the birds in question, it’s better not to use code P.

Waterfowl are an exception to the general rule. They routinely display, form pairs, and even copulate well before they migrate north to their breeding grounds. Wait until after their migration is complete to use code P (and code C) for waterfowl.


What is the difference between agitated and territorial behavior?

An agitated bird (code A) is upset by a different species, generally because that species is perceived as a predator close to the nest. A territorial bird is upset that a competitor is inside its territory. Use code T (territorial) when a bird is upset by an individual of the same species and code A when a bird is upset by a different species. For example, a Red-winged Blackbird chasing a Northern Harrier out of a marsh would receive code A, while two American Robins tussling on the lawn or a Northern Cardinal fighting his reflection would get code T. Be aware that territorial or agitated behavior can occur outside of the breeding season when birds are defending wintering territories, so these codes are best used within each species’ breeding season.


What is the difference between carrying nesting material and nest building?

Use code CN (carrying nesting material) when you see a bird transporting sticks, grass, string, or other nesting material. Use code NB (nest building) when you see a bird at the nest site building their nest. For wrens and woodpeckers, use code B (wren/woodpecker nest building) instead of code NB. Wrens and woodpeckers build dummy nests and roost holes respectively, so nest construction is not certain Confirmation.


When is a nest considered occupied, and when is the bird just visiting a probable nest site?

You should use code ON (occupied nest) when you believe eggs are being incubated or chicks are being brooded but neither are visible. If a bird remains in a cavity or sitting on a nest for a considerable period of time (this is subjective, so use your best judgement and be conservative), you can use code ON. If a raptor is only perched on a nesting platform or if a bird does not remain in a cavity for long, you should use code N (visiting probable nest site). Keep in mind that some species will exchange incubation duties and many species use cavities to roost in at night. If a male enters a cavity and a female leaves, or vice versa, you can use code ON. If you see a bird enter a cavity late in the evening or leave a cavity early in the morning, especially outside of their breeding season, you should not apply a breeding code; this is likely a roost site.


When should I use the fledged young code?

Use code FL (fledged young) when you find a young bird that has recently fledged (meaning it left the nest) and is still dependent on its parents. Do not use it to describe a juvenile bird (meaning a bird hatched that summer) that is independent of its parents—even if it is still with its parents. For example, Canada Geese remain in family groups for most of the year, but you should not use code FL on them once the goslings can fly. Wild Turkey chicks can fly within a couple of weeks, but are still dependent on their mother for a few weeks after that and can receive code FL. Basically, if it looks like a baby bird, you can use code FL.


How much time should I spend finding Confirmed codes?

Confirmed codes—codes that involve nests, eggs, or chicks—are the gold standard of atlasing. If you find a nest, you know that bird nested there! But nests can also be time-consuming to find. Instead of spending a lot of time in your block finding as many Confirmed codes as possible, it is more efficient to look for Probable codes. By focusing on Probable codes, you will find Confirmed codes along the way and cover more ground.

Be especially aware of birds carrying nesting material (code CN), carrying food (code CF), and fledged young (code FL). The young of some birds, such as American Goldfinches or Great Horned Owls, have distinctive calls. Learning these can go a long way towards finding more Confirmed species in your block.


Using eBird


What is the difference between a complete and an incomplete checklist?

When you submit a complete checklist to eBird, you are reporting all the birds that you were able to identify. The opposite is true for an incomplete checklist; you are not reporting all the birds you identified. Each checklist also uses a ‘protocol’ to describe how you were atlasing. You can have Traveling, Stationary, or Incidental checklist protocols. Traveling or Stationary checklist protocols can be complete or incomplete, but Incidental checklist protocols are always incomplete. Since complete checklists are much more valuable for data analysis, you should submit complete checklists whenever possible—but don’t fudge it! If you submit a complete checklist even though it does not include all the birds you identified, you will be submitting misleading data.

Think of the difference between complete and incomplete checklists as the difference between your notebook and a conversation with your neighbor. In your notebook, you record everything you see; this is like a complete checklist. In a conversation with your neighbor, you only mention the highlights from your trip, such as an owl that you found; this is like an incomplete checklist. Both types are useful for different situations.


When should I use the Incidental checklist protocol?

Incidental checklists should be used when you aren’t actively looking for birds; instead you had an ‘incidental’ observation of a bird, like an owl on the side of the road while you were driving. Incidental checklists are always considered incomplete because this protocol assumes that you did not have opportunity to detect other species that were around. It assumes that you are just reporting a notable sighting (like an owl on the side of the road). If you stopped and watched the owl for a few minutes, then you can submit a Stationary, complete checklist. Otherwise, using an Incidental checklist for this situation is the best choice.


Why are complete checklists important?

Submitting a complete checklist means that you reported all of the birds you were able to identify. By submitting a complete checklist, you are also reporting zero for every species that you did not detect. This is tremendously valuable data; zeroes are just as important as the birds you did see. We can use this information to calculate how easy (or hard) it is to detect a bird, then use that detectability number to predict where a species occurs. Creating these predictions is only possible with complete checklists, so whenever you can, try to report all the birds you identify.


If I didn’t detect any birds on my eBird checklist, should I still submit it?

Yes, you should submit checklists even if you did not find any birds. This sometimes happens, especially with nocturnal checklists. Checklists with zero species are still useful for analysis, and they show other atlasers that someone has spent time atlasing in a block. For example, imagine a block that has no owls in it. You spend two hours at night listening for owls, but don’t find any. If you don’t submit that checklist, no one will know anyone was in that block looking for owls.


How do I enter a bird observation someone else told me about?

Your eBird checklists should contain observations that you personally made. You can encourage the original observer to join eBird and participate in the Atlas themselves, or you can go confirm their sighting. Of course, that is not always possible. If the observation is of a common bird (say, a Carolina Wren nesting in their backyard) in a well-atlased area, the Atlas will likely capture similar data for that species. If it is of a less-common species that is unlikely to be observed by someone else (say, a Mourning Warbler nesting in their backyard—wow! Lucky!), then you should contact your County Coordinator and notify them. If possible, provide the original observer’s name and contact information so that any subsequent questions can be directed to the original observer. If your County Coordinator deems it appropriate, they can enter the observation into a regionwide Atlas eBird account.

These second-hand observations are not as important in this Atlas as they have been in the past. In past atlases, it was important to find records of each species in as many blocks as possible because there was no good way to record zeroes—no one knew if a species wasn’t reported or if it wasn’t detected. The only solution was to look harder. Now, complete checklists, observer ID, and effort information all work together to provide information about zeroes. We can couple this information with habitat data to create detailed predictions, or models, about where each species nest in Maryland and DC. Second-hand observations don’t have the complete checklist, observer ID, or effort information that contribute towards creating these models, so they are much less valuable.


How do I submit checklists when I am near a block boundary?

If you are atlasing near a block boundary, you may observe birds in the other block. You should include these birds on your current checklist (this is required for you to submit a complete checklist), but you should not include a breeding code for those individuals. Instead, finish your checklist and make a new, incomplete checklist located where you saw those birds and use the appropriate breeding code. For example, imagine you are atlasing along a lakeshore. The block boundary runs along the middle of the lake. You only want to include breeding codes for the block you are in, not the neighboring block. As you are atlasing, you see a pair of Ospreys perched on a nesting platform across the lake. You enter both Ospreys into your checklist, but you do not include a breeding code for them. After you finish your walk along the lakeshore, you create an incomplete checklist located at the site of the nesting platform. You record two Ospreys on that checklist and include the breeding code N (visiting probable nest site).


How do I submit a checklist with a bird that I’m worried will be disturbed if other people find out where it is?

If you are worried that a bird you found might be disturbed if people learn where it is, you have a couple of options to minimize this risk. First, you can wait eight days to submit your checklist so it will not be included on any eBird rarity or needs email alerts. You can also wait until the end of the nesting season to submit your checklist. A third option is to hide your checklist, but it’s important to note that if you hide your checklist it is also removed from the Atlas database; your observation will not count towards the Atlas. If you hide a checklist, please be sure to unhide it at the end of the nesting season.

If the observation you are concerned about is of a Sensitive species, you can submit your checklist as normal. Sensitive species in Maryland and DC include Black Rail (year round), Northern Goshawk (April–August), Barn Owl (year round), Long-eared Owl (April–September), Short-eared Owl (May–September), Northern Saw-whet Owl (April–September), and Swainson’s Warbler (April–August). These species will not show up on any email alerts, their location on the map is buffered to 150 square miles, and they are concealed on the checklist they were reported on.

If you are unsure whether a bird you found might be susceptible to disturbance, contact your County Coordinator for guidance.

How should I submit a checklist for private land to indicate to other atlasers that there is no public access?

If you had permission to atlas on private land but are concerned that posting a checklist on eBird might encourage other birders to unintentionally trespass, you should include the word ‘private’ in the location title (e.g., Smith Farm—private). This is an unmistakable indication to anyone who views your checklist that the location requires landowner permission before accessing. A second option is to post the location to the nearest road; this can be a good solution if the landowner is uncomfortable with a checklist being posted to their property. If you feel that neither of these options are sufficient, you can also wait to submit your checklist until after the nesting season is finished. Try to avoid submitting checklists at the block level; these checklists are far less valuable for any subsequent analyses.


When should I submit checklists to the Atlas portal?

Your eBird checklists only contribute to the Atlas if you submit them through the Atlas portal. The Atlas portal is essentially a label on your checklist that says it was collected following Atlas methods. If you are aware of breeding behavior, intend to use breeding codes, and are following Atlas methods, then you should submit your checklist to the Atlas portal. Since these requirements probably apply to all of your birding while the Atlas is happening, it basically means you can submit all of your checklists to the Atlas portal.

You can find instructions for how to change portals in Appendix C of the Atlas Handbook, available at ebird.org/atlasmddc/about/handbooks.


How should I code an owl that I heard?

If you hear a single owl hooting, you should use code S (singing). If you hear a duet (listen for this in Great Horned and Barred Owls), you should use code C (courtship display). If you are atlasing at night and using playback (review the Atlas Handbook for guidelines on how to do this safely and effectively), use code T (territorial) on any owls that respond aggressively.


Can I atlas in a block I have not signed up for?

Anyone can atlas anywhere in Maryland and DC, at any time. By becoming the primary atlaser for a block, you agree to make sure the block completion targets are met by the end of the Atlas. Thank you to everyone who has agreed to do this! This helps County Coordinators know which blocks are less likely to receive sufficient effort by the end of the Atlas. Unlike in past atlases, as a primary atlaser you are not responsible for all of the block’s observations and you do not need to verify other people’s observations. Feel free to atlas anywhere and to sign up for as many blocks as you can manage. You can see which blocks are available using the Atlaser Block Tool and you can contact your County Coordinator to sign up.


How are Atlas observations reviewed?

Unlike species or abundance observations, there are no filters that flag unusual breeding codes for eBird reviewers. Instead, reviewers monitor incoming checklists and recent breeding codes submitted in each block. This manual review system is bound to miss some improperly coded species, but that’s okay. Each year, we will filter the dataset using computer scripts and reinterpret unlikely breeding statuses recorded in eBird. This includes things like early or late codes (e.g., code P (pair) for Hooded Mergansers in February), records from well outside where a species is expected to breed (e.g., code S (singing) for a Yellow-rumped Warbler in Harford County), and codes that don’t apply to a given species (e.g., code S for a Black Vulture). The bulk of the quality control will occur during each non-breeding season and prior to our analyses, rather than immediately after an observation has been submitted.


Nocturnal Effort


My checklist started at Sunset so why doesn’t it count for “Nocturnal” hours?

Sunrise and sunset are times when the sun crosses the horizon of the earth. But when the sun is just out of view below the horizon, its light continues to hit our upper atmosphere and scatters and refracts downward upon us, creating Twilight conditions. Diurnal birds are very responsive to this twilight and make noisy dawn and dusk choruses that impede our ability to reliably detect nocturnal birds. So, the atlas excludes twilight hours from nocturnal effort to ensure folks have the best possible chance to detect nighttime birds.


What does BBA3 consider to be a “Nocturnal” checklist?

For a checklist to be included as nocturnal hours in the atlas, both of the following conditions must be true:

  • the checklist must start 20 minutes after official sunset or later, and
  • it must finish 40 minutes before official sunrise or earlier

**eBird checklists don’t literally show an “end time”. However, if you add your checklist’s “Duration” to your “Start Time”, you’ll have the ‘end time’ that BBA3 uses in its calculations.


I did some nocturnal birding but didn’t find any birds, should I report that too, and how?

Absolutely! Your effort provides good information all the same so you should submit a checklist. As we all know, not finding something doesn’t mean it was absent — but knowing you had looked for it helps greatly in predicting the likelihood of its absence. For example, knowing someone had surveyed a forest for nightjars under ideal conditions tells us a lot, even if no birds of any kind were found. This is not an uncommon result for nocturnal surveys. To submit such a checklist, follow the same steps you normally would except: (1) do not add any bird counts, (2) be certain you click “Yes” to indicate that your checklist is complete, and (3) leave a comment in the checklist confirming that you had not detected any birds.


How can I verify that a checklist I had already submitted qualifies as “Nocturnal”?



USE THE EBIRD WEBSITE — Once you log in, navigate to “My eBird” and then select “Manage my checklists”. Open a past checklist and look near the Start Time to see if there’s a prominent black icon with a moon that says, “Nocturnal Observation!“. If you see that icon, then you know your checklist meets the 1st of the 2 nocturnal criteria. The 2nd criterion requires you to do a little mental math to ensure you didn’t cross into morning twilight hours. Simply add your checklist’s Duration to your Start Time and if you ended 40 minutes before official sunrise or earlier, your checklist meets the 2nd criterion as well.


USE THE APP — If you had submitted your checklist using the App, then you have the option of reviewing it there too (in which case, visit your App’s “checklists” page and look under the “submitted” tab). It’s a bummer but there are no automatic “nocturnal” indicators in the app so you must know the official sunset and sunrise times, then do the mental calculations mentioned above. But hey — lucky you — if you’re using the App, you’ve got a mobile device in your hands and you’re just a click away from a weather App that shows sunrise/sunset times!


Darn! I submitted a checklist with nighttime hours that aren’t being counted as “Nocturnal” — how do I fix that?



OPTION 1 — if your checklist missed one of the cutoff times by ~10 minutes or less, simply edit the Start Time and/or Duration so it falls within bounds. This is easiest to do using eBird’s website because as soon as you cross the acceptable Start Time threshold, the prominent black “Nocturnal Observation!” icon will appear. There is no such icon for the ‘end time‘ so you must manually add your Duration to your Start Time and check to make sure that ‘end time‘ is 40 minutes before official sunrise or earlier. **Keep in mind that the goal of a BBA3 nocturnal survey is to, well, survey nighttime birds, which is exactly what you did in your checklist. And so, to that end, lopping off a few extra minutes of twilight birding to ensure your nocturnal survey is represented correctly is worth it because it advances this important BBA3 goal. But it is understandable that some folks may feel uncomfortable doing this because, hypothetically speaking, those two minutes of twilight in their February owling checklist might’ve been when they heard their 15 White-throated Sparrows. So, it goes without saying that you should always try to adjust your bird counts accordingly when/if you have the notes and/or memory recall to be able to do so. But in matters of mere minutes like this, keeping it all in perspective is important too. After all, birders sometimes find 15 White-throats at night simply by losing their footing, tumbling into a bush, and counting the birds that flee into the inky darkness. Point being — the world’s a messy place full of checklists, shrubs, and White-throats, so do your best and don’t anguish in the shrubbery.


OPTION 2 — if your checklist started or ended more than 10 minutes outside the cut off times, then you should split your checklist into two. When done, you’ll end up with (1) a new “nocturnal” checklist that has only your nighttime birding and (2) your original checklist that has been reduced to just your daylight/twilight birding. This is easier to do than it may look but here’s a thorough walkthrough of how to do it:


Step 1 — OPEN your original checklist and jot down on paper:

  • the Start Time
  • the Duration
  • Start Time + Duration (consider this the ‘end time‘)
  • Distance traveled (ignore if stationary)
  • any birds you had detected during the official “nocturnal” time period


Step 2 — LOOK UP the official sunrise and sunset times for that day and place.

  • Google “NOAA sunrise” if you need a source


Step 3 — START a new checklist. You can use either the eBird App or the website to do this but, remember, one advantage of using the website is that it shows a “Nocturnal Observation!” icon when your Start Time qualifies. Complete your checklist as follows (the order will vary depending on if you’re using the Website or App):

  • (if you are using the App) turn off “record track”
  • Location: use the map to select the location where you did your nocturnal birding
  • Date = same date as in your original checklist
  • Observation Type: choose the one that describes your movement during your nighttime birding
  • Start Time: will depend on whether you are splitting a checklist that had run from:
    • day-into-night, in which case make Start Time = official sunset time + 20 minutes
    • night-into-day, make Start Time = same Start Time as in your original checklist
  • Duration also depends if:
    • day-into-night, make Duration = the amount of time that elapsed between this new checklist’s Start Time and your original checklist’s ‘end time
    • night-into-day, begin by subtracting 40 minutes from the official sunrise time. Consider this to be the ‘end time‘ for this new “Nocturnal” checklist. Make Duration = the amount of time elapsed between this new checklist’s Start Time and its ‘end time
  • Distance (ignore if you were stationary) = the Distance shown in your original checklist minus any distance you had traveled outside the “Nocturnal” cutoff time
  • Checklist Comments: it is always best to leave at least some comments to describe the context of your checklist. At the minimum, leave a note something to the effect of, “I had split this checklist out from my original day-into-night checklist“. But notes about weather are also very helpful because birds are more or less likely to have been detected under certain weather patterns, moon phases, etc. A good rule of thumb is to remember that you are not likely to recall this checklist in 10 years’ time, so whatever notes you leave now will probably be the full extent to which you will recollect this night in the future.
  • Birds: enter only those from your original checklist that you had found within the time period of this new checklist
  • Complete Checklist?: always answer “yes” unless you had purposely excluded some birds found during your checklist. **Please don’t do this but, as an example of when someone would appropriately say “no” to this is when they had found a Barred Owl during their checklist but didn’t report it because they knew it was already confirmed in the block. You should always report all birds you detect during a checklist, even if you need to leave the count as “X”. The eBird website includes a clickable “?” next to this question that provides additional information about its purpose.


Step 4 — SUBMIT your new “Nocturnal” checklist


Step 5 — OPEN and EDIT your original checklist. You can use the eBird website to do this or, if you had submitted your original checklist using the App, you have the option of editing it there too (in which case, visit your App’s “checklists” page and look under the “submitted” tab). **PLEASE NOTE: If you are new to editing checklists in eBird and feel frustrated at any point, contact your county coordinator and walk through it together; they are there to help you.

  • Location: no change
  • Date: no change
  • Observation Type: only change if needed
  • Start Time: if this checklist had originally run:
    • day-into-night, then no change
    • night-into-day, make Start Time = official sunrise – 39 minutes (i.e., Start Time should be 1 min. after your new “Nocturnal” checklist had ended)
  • Duration = original Duration minus the Duration reported in your new “Nocturnal” checklist
  • Distance (ignore this if stationary) = original Distance minus the Distance reported in your new “Nocturnal” checklist
  • Track (if you have one): at the time of writing this (Feb. 2022), you cannot edit a Track in a submitted checklist. **Recognize that tracks are an optional feature that’s separate from Distance and Duration, which are required values in all checklists. The App’s Track feature was designed to precisely map your travels during a checklist by using the built-in GPS of your mobile device. When you stop the track feature, the App takes advantage of the track you had made by measuring its length and how many minutes it had run for. It then passes those values into your checklist before you’ve submitted it, saving you the trouble of having to calculate Distance and Duration yourself. But because all of that happens before your checklist is submitted, once you hit submit, there’s no remaining linkage between them. You should update your Distance and Duration whenever it’s needed to keep them accurate because those are required values.
  • Checklist Comments: at the minimum, leave a note something to the effect of, “I had split this checklist out from my original day-into-night checklist“. But providing more contextual information is always helpful since you will not likely remember this information when you look back on it in ten years’ time.
  • Birds: remove any that you had included in your new “Nocturnal” checklist
  • Complete Checklist?: always answer “yes” unless you had purposely excluded some birds found during your checklist


Step 6 — SAVE this checklist. Congratulations, you’re all done!