Map of winter atlas blocks.

LA County Trial Winter Bird Atlas

Dec 2021 to Feb 2022

Get ready for the Los Angeles County Winter Bird Atlas! This is a trial atlas that involves a survey of wintering birds in thirteen “blocks” that were selected to cover the various types of habitat in Los Angeles County. The survey runs from December 1, 2021 through February 15, 2022. We plan to follow up with a much more ambitious project in several years (possibly 2024-2025 or 2025-2026): a winter atlas covering the entire county.

The following interactive map shows the blocks that will be covered in this trial atlas, and the eBird hotspots in each block:

Below is the same map, but in satellite view instead of street view:


Preliminary preparations are underway for the second Los Angeles County Bird Atlas, which we hope to begin in 2025. In 1995-1999 we conducted the first Los Angeles County Breeding Bird Atlas (Allen et al. 2016), but with the second Atlas, we seek to conduct a winter atlas as well, which we have not done before.

In preparation for the winter atlas, and to familiarize ourselves with winter protocols, use of eBird for data entry, and to identify and solve logistical issues, we’re going to conduct a trial survey in the winter of 2021-2022 with a subset of blocks previously used in the 1995-1999 Atlas.


Survey Period: December 1, 2021-February 15, 2022.

eBird will be our principal tool for data entry. eBird will enable us to track progress quickly and will require considerably less work than manually entering data submitted by email or regular mail.

Our trial winter atlas will use 13 5.8 km x 4.6 km (3.6 mile x 2.9 mile) blocks, following the convention adopted in the 1995-1999 Atlas by Allen et al. (2016). Each block was obtained by dividing the United States Geological Survey 7.5’ topographic rectangles for the county into six regions of equal area. The 2021-2022 winter survey is a practice run and we will not attempt to survey all 400+ blocks that were included in the 1995-1999 Atlas.

The 13 trial blocks cover most of the major habitat types in Los Angeles County and also cover all but one of the larger 12 regions utilized in the Atlas from 1995-1999. We wanted to strike a balance between covering as many habitats as possible while also keeping the number of trial blocks to a manageable number.

A key rationale for conducting the trial winter atlas is to assess the number of survey hours necessary to achieve a reasonable level of completeness for each block. For this trial winter atlas, we want a minimum of 20 HOURS to designate a block as complete.

The 20 hours will consist entirely of birding during the day but we also welcome additional observations obtained at night, which we define as more than 20 minutes after sunset or more than 40 minutes before sunrise. Time contributed at night does not count toward the 20 hours necessary for completing a block.

The map on this website outlines the trial blocks in purple. You can zoom in to see the details of each block in either a street view or as a satellite view.

To contribute to the trial winter atlas, simply go to one of the atlas blocks, use normal ebird protocols to keep track of the numbers of each species you find, and then enter the data either using the eBird phone app or on a computer. Please enter “complete” lists that have specific start and stop times. This allows us to track the number of hours of effort in each block. Traveling, stationary, and areal are all examples of complete lists. Incidental checklists are also welcome but by definition they do not count toward the 20 hours (but the species documented will be recorded).

Group counts: for timekeeping purposes, we count the time of each group as one list (following the protocol used for Christmas Bird Counts). Thus, if a group of three people spend one hour in an area, that counts as one hour, not three.

In some instances it will be necessary to pay careful attention to block boundaries because some popular eBird hotspots are just outside or inside block edges (more on this below).

The trial blocks were chosen partly to avoid locations with very active hotspots (Piute Ponds, Malibu Lagoon, Bonelli Park, etc.) that already receive extensive coverage. However, a few of the blocks have hotspots such as the Caltech campus, the lower Arroyo Seco, and Zuma Beach that get decent amount of coverage, but other blocks are sparsely covered.

Surveys in multiple blocks are encouraged: there no need to limit efforts to only one. For this trial atlas, we are NOT asking people to formally sign up for any particular block. Due to our use of eBird, we will monitor progress toward completion on a weekly basis, so we’ll know quickly if some blocks are not getting coverage. It is also fine if blocks receive more than 20 hours of eBird lists. We will post results on the Los Angeles Birders website on a weekly basis.

We recommend having a map with you in the field to know your location on a block. There are several ways of doing this:

We also seek to determine how many species are present in each block during the winter, but we do not have target numbers that we expect to reach.

None of the trial blocks was affected in a significant way by the Bobcat Fire closure, which is scheduled to expire on April 1, 2022.

Identifications can be made visually or by sound, and as always, rare birds require documentation.

We will check eBird data and update our progress weekly on the Los Angeles Birders website. We may also hold informal Zoom meetings every 2-3 weeks to discuss progress, answer questions, and hear your suggestions.

Detailed information about each trial block


The following table shows the correspondence between the names of the blocks in the trial atlas, the names used in the Breeding Bird Atlas (Allen et al. (2016)), and the Christmas Bird Count circles (if any) that contain or overlap each block. Clicking on the block name downloads a PDF map of the block; but it may be easier to get the block map on your phone.

Block Allen et al. (2016) notation CBC Overlap
LON CE Long Beach 4 Region 1 Long Beach
TOP CE Topanga 4 Region 2 Los Angeles: only a bit
POI SW Point Dume 5 Region 2 Malibu: sliver on the SW
SOU NW South Gate 1 Region 3
SAD NW San Dimas 1 Region 4 Pomona
SAF SW San Fernando 5 Region 5 San Fernando
SAF NE San Fernando 2 Region 5 Santa Clarita: barely in the south
PAS SE Pasadena 6 Region 6 Pasadena
CRY CW Crystal Lake 3 Region 7
PAC NW Pacifico Mountain 1 Region 9
LIE NW Liebre Mountain 1 Region 10
LAE CW Lancaster East 3 Region 11 Lancaster
HIV CE Hi Vista 4 Region 12

Notes about each block:

Hotspots in each block

Most of the trial blocks have only a few eBird hotspots that aren’t close to the block edges, but some have hotspots that are barely inside or outside the blocks. In those cases, please pay close attention to your location relative to the block boundary. If the eBird hotspot is barely inside the block (examples: Caltech campus, Oakdale Memorial Park), please use the hotspot and please enter into your eBird checklist notes that you are counting birds only inside the block. If the eBird hotspot is barely outside the block (example: Saddleback Butte State Park), please do not use the hotspot but instead please create and use a personal hotspot that is inside the block, survey the area within the block, and enter into your eBird checklist notes that you are counting birds only inside the block.

Here are some known eBird hotspots that could cause trouble:

Here is a webinar explaining details of the trial atlas: