Block Completion Guidelines

[UPDATED JAN 1, 2023]

The Block Coverage Guidelines suggest when a block is complete and it’s time to move on and survey a new priority block. It becomes increasingly difficult to add new species and breeding codes as more time is spent in a block. At a certain point your atlas effort is better spent in another block. The block coverage guidelines help us determine when atlas effort is adequate (marked “complete” in eBird) in a block and you should spend your time elsewhere.

Block Coverage Guidelines

These metrics apply to the cumulative effort of all atlasers in a block over the entire 5-year project period. A running total of species and effort within your block can be found on the eBird portal.

When you think a block meets these guidelines, please email your Regional Coordinator and they will evaluate the block for completion.

For more detailed instructions on how to assess a block, read this post.

Visited at 3+ times of year

Aim to survey each block at different times of the breeding season (e.g., April, June, July) to capture species that breed at different times of the year.

All accessible habitat types in a block are visited

All of the major habitat types in a block should be visited to ensure that we record the full diversity of species breeding per block. Major habitat types include deciduous, coniferous, and mixed forests; shrubland and early successional habitat; grassland; wetlands; coastal beaches; and montane areas. If a significant habitat type is not public, please use landowner letters to request access. Access will be denied in some areas, but please try! You can also ask your Regional Coordinator for assistance in gaining access.

20 hours of daytime birding

Studies based on other atlas projects indicate that 20 hours is the average time it takes to adequately survey a block. Some of the factors that influence how long it will take to finish a block are observer skill, access, and habitat diversity. Experienced birders are able to identify species by ear and are familiar with the local habitat requirements of species so it may take them less time on average to atlas a block. If the land is difficult to access, either with little public land or few roads and trails, it will take longer to atlas the block. Some blocks contain fairly uniform habitat and it will take longer to increase the species count.

55-95+ species reported

The number of species breeding in a block is highly variable depending on geographic location and local habitat diversity. Areas like Long Island and the Adirondacks support fewer species than central New York. To gauge how many species you should target in your block, use the atlas effort map on eBird to see how many species have been documented in nearby blocks. You can also refer to the second atlas results to see how many species were reported in the same general area.

45 species or 67% of reported species marked as ‘Probable’ or ‘Confirmed’

This guideline was revised 1/1/2023 (formerly 50% of species needed to be ‘confirmed’). At least 45 of the species reported in a block should be documented with a ‘Probable’ or ‘Confirmed’ breeding code. Refer to the breeding code section of this handbook for a list of Probable and Confirmed codes. To determine how many species have been reported as Probable and Confirmed, go to the atlas effort map, click on your block, and follow the “View all block data” link. Alternatively, from the PDF of the block map, click on the link just above the map. The top of the detailed block data page shows the total number of species reported according to three breeding categories: Possible, Probable, or Confirmed. Add the number of Probable and Confirmed. Alternatively, for blocks with low species richness, use 67% of species as the threshold. Divide the Total by the number of (Probable + Confirmed) to determine if a block meets the 67% threshold.

2 hours of nocturnal birding (strongly recommended)

Nocturnal effort is optional (though strongly recommended) as of 1/1/2023. Nocturnal surveys are important to capture crepuscular and nocturnal species like nightjars, owls, and rails. eBird defines a nocturnal checklist as starting more than 20 minutes after sunset and ending 40 minutes before sunrise. We recommend making at least two nocturnal visits per block, once in March or April to capture owls and again in May or June for nightjars and rails.

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