Date: 9/7/26 7:39 pm From: Lance Benner via groups.io <lbenner...> Subject: [LACoBirds] Bird Atlas Results for Los Angeles County: Sep. 7 update
Hi Everyone,
Here's another California Bird Atlas update for Los Angeles County.
As of September 7:
Total blocks: 434
Blocks with data: 385 (89%)
Blocks with no data: 49
Atlasers: 929
eBird checklists: 18816
LA County atlasers who have contributed 40+ checklists: 93
Atlas hours: ~15160
Species Coded: 269 (coded = possible + probable + confirmed)
Species Confirmed 180
To date, we have coded at least 50 species in 79 blocks, and of those, at least 50% of the coded species have been confirmed for 32 blocks.
Here are all the blocks where at least 50 species have been coded. They're ranked in decreasing order of the number of species coded, following the protocol used in the first LA County atlas in the 1990s.
Conf Coded %Conf #estimated block_name
76 109 0.70 62 C San Dimas NE
54 95 0.57 60 C Burbank SE
65 94 0.69 68 C Pasadena CE
35 92 0.38 77 San Fernando SE
47 89 0.53 60 C Van Nuys CW
40 87 0.46 42 Long Beach CW
41 85 0.48 67 Los Angeles NW
58 83 0.70 76 C El Monte SE
53 82 0.65 64 C Hollywood NE
42 81 0.52 64 C Valyermo NW
45 80 0.56 52 C Venice NE
27 79 0.30 98 Mount Wilson CE
32 78 0.41 60 Malibu Beach NW
50 78 0.64 60 C Pasadena SE
56 76 0.74 70 C Newhall CW
44 75 0.59 64 C Baldwin Park NW
39 75 0.52 51 C Mount Wilson SW
54 75 0.72 40 C Whittier SE
32 74. 0.43 64 Chilao Flat CE
37 74 0.50 66 C Glendora SE
07 74 0.095 76 Lake Hughes CW
45 74 0.61 64 C Mount Wilson SE
54 74 0.73 64 C San Dimas CE
41 72 0.57 54 C Ontario NW
39 71 0.55 67 C Pasadena CW
30 70 0.43 50 Long Beach NW
29 69 0.42 72 Glendora SW
27 68 0.40 72 Mount Wilson CW
46 67 0.69 57 C Los Alamitos CW
22 66 0.33 67 Chilao Flat SW
27 66 0.41 84 Mescal Creek SW
29 66 0.44 48 Rosamond Lake CW
23 64 0.36 65 Mount Wilson NE
19 64 0.30 65 San Dimas CW
21 64 0.33 39 Venice NW
25 63 0.40 50 Burbank SW
32 62 0.52 71 C Azusa SE. Could code more
33 62 0.53 57 C San Dimas NW
23 62 0.37 70 Valyermo CW
19 62 0.31 67 Waterman Mountain NW
22 61 0.36 68 Pasadena NE
37 61 0.61 56 C Torrance SE
35 60 0.58 55 C El Monte NE
17 60 0.28 79 Mint Canyon SW
20 60 0.33 63 Mount San Antonio NW
34 60 0.57 53 C Whittier NW
21 59 0.36 71 Azusa NE
32 58 0.55 53 C Beverly Hills NE
20 58 0.34 55 Hollywood NW
15 57 0.26 71 Mount Baldy NW. Previous atlas lumped NW and NE
18 57 0.32 77 Point Dume NE
15 56 0.27 73 Agua Dulce CE
31 56 0.55 50 C Hollywood SW
32 56 0.57 35 C Long Beach CE
28 56 0.50 51 C Los Angeles CW
17 55. 0.31. 77 Azusa CW
13 55 0.24 61 Chilao Flat SE
32 55 0.58 25 C Long Beach SE
21 55 0.38 72 Mount Baldy SW
29 54. 0.54 27 C Los Alamitos NW
15 54 0.28 71 Pasadena NW
13 54 0.24 84 Valyermo SE
24 53 0.45 40 El Monte NW
25 53 0.47 61 La Habra NW
21 53 0.40 23 Redondo Beach NE
21 53 0.40 65 Torrance CW
21 52 0.40 54 El Monte SW
15 52 0.29 63 Malibu Beach NE
18 52 0.35 63 Mint Canyon CE
18 52 0.35 62 Point Dume NW
24 52 0.46 52 Rosamond Lake SW
12 52 0.23 73 San Fernando NE
12 51 0.24 61 Condor Peak SE
24 51 0.47 81 Malibu Beach SE. Previous atlas lumped it with CE
26 51 0.52 54 C Pasadena SW. 53 species coded last time.
09 51 0.18 74 Sunland SW
11 51 0.22 66 Whitaker Peak NE
16 50 0.32 67 Mount Wilson NW
12 50 0.24 54 Palmdale SE
N = 79 blocks with at least 50 species coded.
(The columns above were aligned when I wrote the email, but no guarantees they'll appear aligned in your email!)
In the table above, the left column gives the number of species for which breeding has been confirmed, the 2nd column gives the number coded, the third column gives the percentage of species where breeding has been confirmed, the fourth column gives the number of species expected (from the atlas in the 1990s), and then on the far right is the name of the block. If an upper case "C" appears then the block would be considered complete by criteria adopted for the first LA County atlas.
For many blocks above, we have already coded more species than were estimated to be present during the atlas in the 1990s. For other blocks, though, there are still a lot more species we could find that haven't been reported yet.
Completeness criteria adopted, from the first atlas in the 1990s:
At least 90% of expected species coded, at least 50% of them confirmed, and the total number coded is at least as many as estimated for the first atlas.
If we consider only blocks with 50+ species coded, then 32 (7.3%) of the blocks are complete.
But if we include blocks with at least 40 species coded (not shown above to save space), then the number of complete blocks increases to 34, so at least 34/434 = 7.8% of blocks in the county are complete.
That's pretty good for the first year of an atlas, given that most of us hadn't particpated in a bird atlas previously, and that we've been learning how to do this as we go.
Given that many of us are now experienced and that we've made good progress in many blocks, it's likely that the number of complete blocks will jump significantly next year.
What are the protocols for completing a block in the CURRENT atlas?
That will be announced by early next year, but it's likely to involve the number of species coded for each block and the percentage relative to the number of species expected. We're monitoring those statistics using the Blockboard progress tracker tool, which is available online at:
"Blockboard" uses estimates of the number of species that could be present in each block based on previous eBird reports; this distribution model is provided by eBird central.
As a result, it's really important that you include breeding codes in your checklists whenever possible because they are crucial for monitoring our progress. I mention this because A LOT of species reported in eBird in the atlas portal in Los Angeles County DO NOT have breeding codes: many observers simply didn't report them, particularly for lower levels of breeding evidence such as "H-in suitable habitat" and "S-singing bird", and as a result, the numbers in the eBird portal and in the Blockboard tool underestimate the actual numbers of species in most of the blocks. In blocks where 40+ species have been reported, the underestimate is often at the 10-20% level; in blocks with only a little coverage, often only 1/2 to 1/4 of the species have received breeding codes. PLEASE USE BREEDING CODES!
What about blocks in LA County with zero coverage?
Blocks with zero data are concentrated in the Antelope Valley, remote regions of the San Gabriel Mountains, remote regions of the mountains north of Santa Clarita, and on Santa Catalina and San Clemente Islands.
The blocks in the Antelope Valley and along the north slope of the mountains are accessible by car but there are at least 10 blocks in the mountains that are accessible only on trails or on dirt roads that are either behind locked gates or too rough for even 4WD vehicles.
To view our coverage with individual blocks you can check the Blockboard tool above or go to a somewhat different (and less complicated) map on the eBird website:
and then zoom in on Los Angeles County. The default setting for this map shows "Diurnal effort hours," but you can toggle it to other settings, such as "Coded species" or "Confirmed species" that are arguably more useful.
Meanwhile, observers are still confirming breeding for species across Los Angeles County even though we're into early September, so please continue to use the atlas eBird portal and report all levels of breeding evidence in your eBird lists.
Also, several of you are working behind the scenes to arrange access to areas that are normally off-limits to the public. Thank you very much for your help with this! If you're one of those people but you haven't reached out to us yet to let us know, please send an email so we can keep track and avoid duplicating effort. We really appreciate your help!
Once again, if you haven't already contributed to the atlas, please join us! Even checklists in your yard and neighborhood are useful (often they're VERY useful).
and then click on the rectangle stating "Join Project" on the lower left. When you enter birds in eBird, be sure to drop down the menu for breeding codes and select the ones that are appropriate for behavior you observe.
From a smartphone using the eBird mobile app, select "Choose Projects" on the home screen and then select the California Bird Atlas. If you don't see "Choose Projects" then you may need to update to the latest version of the app.
Thank you again for your all your help with the atlas!
