Nocturnal Flight Call Count protocol

Nocturnal Flight Call (NFC) counts have different detection rates than diurnal counts and large numbers of repeated NFC counts can skew eBird data. This protocol allows researchers quick and easy access to the NFC data and tags them to be treated differently in eBird output. It is very important that you read and understand the protocol requirements below since this count does differ in some important ways from other eBird counts, especially in reporting all species, the use of the species comments field (required), and how species are counted.

Nocturnal count: Counts should be conducted only at night, which is defined as the when the sun is more than 12 degrees below the horizon (the period between astronomical dusk and astronomical dawn).

Effort: Start time and duration are required fields. The protocol assumes you are conducting a stationary count.

Reporting all species: If you choose this protocol, you must report all species you were able to identify to the best of your ability (if you are reporting highlights only, please use Incidental). However, we ask that you select “no” to this question when submitting a checklist. This is because these counts are not comparable to other eBird surveys and the frequency could skew eBird output.

Bird counting: We ask that you count the number of calls and, when possible, try to estimate the number of birds present. However, counting unseen birds at night is extremely challenging and prone to very large errors. Calling rates vary tremendously because of geography, ground lighting, weather, and other factors. In addition, many migrants are known to circle, especially around light sources. With all these factors in mind, we encourage observers to count individuals only when they are truly confident that their counts are representative (i.e., low numbers or very clear instances of individuals or small groups moving past). Use an ‘x’ if the species was recorded but counts were uncertain, but please do provide call counts if possible (see below).

Call counts and species comments: Many nocturnal flight call researchers also use the number of calls as an important metric. If you count these also (which we encourage), please enter them in the species comments immediately after “NFC”. For example, please enter “NFC 17” to signify 17 calls heard from that species or “NFC 187” to signify 187 calls heard. In many cases, it will not be possible to estimate the numbers of individuals but it will be possible to count calls. In cases where you detected a species by NFC, but did not count the calls, please enter “NFC” without the count.

Please also indicate birds on the ground or on territory nearby with the phrase “local”. This will ensure that territorial birds are not used in the analysis. Enter any additional comments only after a pipe separator “|”. For example:

Species identifications: Since many species identifications by flight note are extremely difficult, please make liberal use of warbler sp., Catharus sp., sparrow sp., passerine sp., and similar categories where appropriate.

Date: Please note that for all these protocols, a separate checklist should be entered for observations after 12:00 a.m., since eBird requires a specific date. Checklists that span midnight (e.g., start time of 11:00 p.m. and duration of 2 hours) should not be entered. As stated above, checklists should be conducted at night (defined as between the beginning and end of astronomical twilight).

eBird output: Since they are tagged as “not all species reported,” these counts will be treated differently from diurnal counts in eBird bar charts and maps. Specifically, the records will show up on eBird output, but will not be used in frequency calculations (e.g., bar charts, grid maps, line graphs) at this time.

Remote listening: We are well aware that some observers use remote listening stations to record nocturnal flights and later catalog the calls heard. The detection using recording devices in fundamentally different; please do not enter these in eBird at this stage.