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Entering Nocturnal Flight Call Counts

[Update 21 Oct 2014: Note that the "Bird counting" section has been modified slightly to clarify that counts should reflect counts or estimates of total birds, NOT flight call counts. A separate section (with no new changes) addresses how to record flight call counts in species comments.]

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 generally defined as the when the sun is more than 18 degrees below the horizon (the period between astronomical dusk and astronomical dawn). Please note, we strongly encourage you to use this protocol during astronomical dusk to astronomical dawn. However, you may submit counts between civil and astronomical twilights (when the sun is between 6-18 degrees below the horizon), but you must follow all instructions below and make sure to submit separate checklists for counts in this period. For example, if you begin your count at civil twilight and continue until midnight, we ask that you separate the period before astronomical twilight from the periods after astronomical twilight.

Effort: Start time and duration are required fields. Ideally, counts should be hourly or sub-hourly, if possible. 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 the Incidental protocol). This includes flight-calling migrants and local singing or calling birds (see below). However, we ask that you answer “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.

Since a specific protocol is used and since the assumption for all counts using this protocol is that all species are reported, it becomes possible to still analyze these data as complete checklists when the data are downloaded.

Bird counting: We ask that you do your best to estimate the number of birds you detected; please enter this count or estimate in the count field for eBird. Note that 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). We encourage counts of total nocturnal flight calls heard as well (which is typically less challenging); see the below section for how to record these.

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 is very important for all counts using this protocol, but particularly so for those counts occurring in the periods before astronomical dusk and after astronomical dawn. Local birds may include owls, nightjars and other species like Northern Mockingbird and Yellow-breasted Chat that regularly sing at night. This will ensure that territorial birds are not used in the analysis of nocturnal migrants. 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.

Documentation: Many NFCs are difficult to identify, and some locally rare species may be more easily detected through NFCs than through traditional birding on the ground. Please document rare, unusual, or hard to identify NFCs through recordings whenever possible. We suggest that you upload recordings to Xeno-Canto.org or some other online repository, and include the link to the call in the species comment section, as well as a discussion of how the NFC was identified. Embedding images (see instructions) of the spectrograms is also perfectly appropriate documentation (please include spectrogram parameters if you can). Here is a great example for the first Hunterdon Co., NJ, eBird record of Whimbrel recorded via NFC.

Date: Please note that 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.

Amplified or directional listening: Using a directional microphone or parabola with a microphone can greatly increase detection of flight calls directly overhead, but also is less likely to record calls or calling birds outside of the cone of the microphone array. 

It is appropriate to use directional microphones, parabolas, and other systems to allow you to listen to NFCs and other birds either indoors or outside. If you do use such methods, please be sure to include the metadata for your array in the Checklist Comments. It is important to clarify that it is OK to enter these data through your personal account, but if you are not listening to the birds in real time then the data should be entered as a Remote Station (i.e., if you review a recording after it was made to see what species were recorded; see below for more detail).

Listening station metadata: Anytime you use microphone for a NFC listening station, we ask that you enter the metadata in the comments. This can be a standard text block that you store and paste each time you use this protocol. If you use a mix of unaided ear and listening station, be sure to clearly indicate which you use for each NFC count. Without metadata, we assume that all NFC counts are using the unaided ear. 

At a minimum, this should include documentation of microphone type, recording device, any analysis methods or software used, and comments on methods of identification and review of your data. 

Remote listening

Records from remote stations should not be entered under a personal account, since "games" like Top100 and Yard/Patch are important incentives from our non-robot users. We need to make sure that eBird data not collected by you in person be kept separate from your personal account. If you are not listening live (i.e., you are recording NFCs from a remote location or at your home while you are sleeping), please set up a "remote listening account" (see below). Please make sure, however, to meet all requirements and requests mentioned above (e.g. making sure to report all the species you can identify, whether you detect flight-calling migrants or singing owls).

As with the Nocturnal Flight Call Count protocol, if you want to submit just a highlights list from your NFC recorder you may do so using the "Incidental" protocol.

This protocol initially (spring 2012) recommended not submitting data from remote stations, but this is an increasingly popular way to survey nocturnal migration. The data often include valuable information on the migration and occurrence of species that are hard to detect by other methods and is appropriate for eBird, provided that the data be clearly marked as not coming from a human observer.

Including your remote data would give unfair advantages not shared by those that only submit birds witnessed in person.

To address the above concerns, please follow the below recommendations when submitting data from a remote NFC station:

Remote listening account: Please use a separate account from your personal account to record the data. Please use your email address, but use your full name followed by "NFC Station", which will flag the account as a remote NFC Station. For example, enter first name "Andrew Farnsworth" and Last name "NFC Station". Please follow these conventions exactly so that we can easily identify all NFC stations by the "Last Name" field in our database.

Remote listening metadata: As noted in "listening station metadata" above, please include the technical specs for your count on at least your first submitted count. Since it is safe to assume that the same array is used over time, you do not need to report this every time when using a "NFC Station" account. However, it is good practice to include it with each submission. For example:

If you make any change to your system, please make sure that is reflected in the metadata. For example, if you change the software you use to filter bird calls from a night of recording data, please annotate that in your comments. If you change the microphone, see "Changes to your NFC station" below. 

Changes to your NFC station: If you substantially change the microphone used in your NFC recording station, please create a separate account. Since the technical details of your setup have important detection implications, this is very important. You can then rename your accounts "Andrew Farnsworth NFC Station 1" and "Andrew Farnsworth NFC Station 2" etc. This is not necessary if you change your data filtering methods, although those changes should be reflected in your station metadata.

Remote listening locations: You may create a unique location for your NFC station or you may use the same location(s) from your personal account, if for example you want to have all reports from your yard under a single location. To achieve this, you can share a checklist (any checklist) with your NFC account. Accept the checklist in your NFC station account and then delete it. The location of the shared checklist (e.g., your yard) will remain in your "My Locations" list and will be available for data entry from that point forth. The data will be merged on eBird output.

 

Thank you for your NFC data and thanks for following the above recommendations.

 

Team eBird (Marshall, Chris, and Brian) and Team BirdCast (Andrew Farnsworth) 

help@ebird.org
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