Atlas Data Review

By Julie Hart October 30, 2020
Common Eider (Northern) Somateria mollissima borealis

After a hugely successful first season, it’s time for some data review! Stay tuned for more focused species maps and cleaner block data to better help you strategize your 2021 atlasing!

Why review data now?

With more than 2 million breeding behavior observations from the first year of the atlas, there are bound to be some errors. Some problems are due to data entry errors, while others may result from not following the guidelines such as crossing block boundaries or using a breeding code that doesn’t apply to a given species.

How are data being reviewed?

To start, we are looking for inaccuracies in behavior codes, dates, and locations. These inaccuracies (e.g., a Brown-headed Cowbird building a nest (NB), a 50-mile checklist that crosses 10 blocks), will not display in public data after the review.

Secondarily, we’re evaluating all breeding behavior codes where the evidence category (i.e., Observed, Possible, Probable, or Confirmed) should be changed. This is a process called reinterpretation. If you’ve noticed that the effort map and block pages show Possible or Probable breeding for species that do not breed in the area, the reinterpretation process should greatly improve these for everything from courting ducks, to singing migrants, and much more.

What is code “reinterpretation”?

Not all breeding behaviors indicate local breeding. For example, not all courtship happens in the location where the birds breed and not all birds seen carrying food are necessarily carrying food to their young. Even though the behavior of singing and courting are correctly identified, we can interpret the information in different ways.

A singing Cape May Warbler in Central Park on 20 May is an example of an observation that should be reinterpreted. Because the bird was singing, it received the code S (correctly!), but the standard association of “Possible” breeding doesn’t make sense here. After “reinterpretation,” we’ll be able to retain the observation that there was a singing Cape May Warbler in Central Park on 20 May, but it won’t appear as “Possible” for the block or on the Species Map.

Note that the original breeding code is unchanged, only the breeding category is changed. By changing the breeding category, this will change how a particular observation shows up on the species map and block pages.

Here is an example from the Maine Atlas of how reinterpreted codes will appear on checklists. While the eiders were correctly reported as courting, this does not mean that they are local breeders. Note that only the evidence category is changed, not the original observation.

Read more about breedubg code reinterpretation on the eBird Help pages.

How are we looking for data quality concerns?

All the data will pass through filters based on the Breeding Guideline Bar Chart and Acceptable Codes Chart. In addition, maps for each species will be reviewed for obvious outliers. Outlier observations will then be reinterpreted and/or the observer will be asked to provide additional details. If you are contacted for additional details, please respond as quickly as possible with any documentation you can add. This will be an iterative process since the breeding phenology of birds in NY is shifting. This is a chance for everyone involved to learn something new.

When will the changes take effect?

Late winter or early spring. At that time, we will also be providing tips on how to use the updated block info to identify gaps and finish blocks.

Should I keep using the portal and entering codes in the off-season?

Yes! You should continue to enter breeding behavior codes and use the Atlas portal year-round as long as you are not crossing block boundaries. Some species sing well into the fall and other species start courtship behaviors in early winter.

Even though your observations may be reinterpreted to indicate local breeding status, this does not mean that your observation was incorrect. In fact, the information provided helps us learn additional details about breeding phenology in the state. By doing your best to follow the Atlas guidelines, you will maximize the value of your observations for science and conservation.