60 birds were recorded seen in California in May in our iNaturalist sample; 4 of the top 50 are at their peak this month. The list is ranked by number of research-grade observations.
Top birds in May

Mallard
House Finch
California Scrub-Jay

California Towhee
Canada Goose

Red-tailed Hawk
Anna's Hummingbird

Western Bluebird

Mourning Dove

Dark-eyed Junco
Black Phoebe
Lesser Goldfinch
All birds seen in California in May
| # | Species | Scientific name | Family | Obs. | Peak in state |
|---|---|---|---|---|---|
| 1 | Mallard | Anas platyrhynchos | Ducks, Geese, and Swans | 10,003 | Apr (past peak) |
| 2 | House Finch | Haemorhous mexicanus | Finches, Euphonias, and Allies | 9,942 | Apr (past peak) |
| 3 | California Scrub-Jay | Aphelocoma californica | Crows, Jays, and Magpies | 7,451 | Apr (past peak) |
| 4 | California Towhee | Melozone crissalis | New World Sparrows | 7,449 | Apr (past peak) |
| 5 | Canada Goose | Branta canadensis | Ducks, Geese, and Swans | 7,243 | Apr (past peak) |
| 6 | Red-tailed Hawk | Buteo jamaicensis | Hawks, Eagles, and Kites | 7,215 | Jan (past peak) |
| 7 | Anna's Hummingbird | Calypte anna | Hummingbirds | 7,123 | Apr (past peak) |
| 8 | Western Bluebird | Sialia mexicana | Thrushes | 6,655 | Apr (past peak) |
| 9 | Mourning Dove | Zenaida macroura | Pigeons and Doves | 6,649 | Apr (past peak) |
| 10 | Dark-eyed Junco | Junco hyemalis | New World Sparrows | 6,506 | Apr (past peak) |
| 11 | Black Phoebe | Sayornis nigricans | Tyrant Flycatchers | 6,479 | Apr (past peak) |
| 12 | Lesser Goldfinch | Spinus psaltria | Finches, Euphonias, and Allies | 6,356 | Apr (past peak) |
| 13 | Song Sparrow | Melospiza melodia | New World Sparrows | 5,896 | Apr (past peak) |
| 14 | Great Blue Heron | Ardea herodias | Herons, Egrets, and Bitterns | 5,890 | Jan (past peak) |
| 15 | Black-crowned Night Heron | Nycticorax nycticorax | Herons, Egrets, and Bitterns | 5,655 | Apr (past peak) |
| 16 | Western Gull | Larus occidentalis | Gulls, Terns, and Skimmers | 5,120 | Aug (rising) |
| 17 | Northern Mockingbird | Mimus polyglottos | Mockingbirds and Thrashers | 4,822 | Apr (past peak) |
| 18 | California Quail | Callipepla californica | New World Quails | 4,719 | Apr (past peak) |
| 19 | Acorn Woodpecker | Melanerpes formicivorus | Woodpeckers | 4,603 | Apr (past peak) |
| 20 | Spotted Towhee | Pipilo maculatus | New World Sparrows | 4,383 | May (peak) |
| 21 | Turkey Vulture | Cathartes aura | New World Vultures | 4,380 | Apr (past peak) |
| 22 | Red-winged Blackbird | Agelaius phoeniceus | New World Blackbirds and Orioles | 4,371 | Apr (past peak) |
| 23 | Snowy Egret | Egretta thula | Herons, Egrets, and Bitterns | 4,287 | Jan (past peak) |
| 24 | American Crow | Corvus brachyrhynchos | Crows, Jays, and Magpies | 4,273 | Apr (past peak) |
| 25 | House Sparrow | Passer domesticus | Old World Sparrows | 4,091 | Apr (past peak) |
| 26 | Brown Pelican | Pelecanus occidentalis | Pelicans | 3,958 | Sep (rising) |
| 27 | Wild Turkey | Meleagris gallopavo | Pheasants, Grouse, and Allies | 3,941 | Apr (past peak) |
| 28 | Hooded Oriole | Icterus cucullatus | New World Blackbirds and Orioles | 3,893 | Apr (past peak) |
| 29 | American Robin | Turdus migratorius | Thrushes | 3,842 | Apr (past peak) |
| 30 | Common Raven | Corvus corax | Crows, Jays, and Magpies | 3,621 | Apr (past peak) |
| 31 | Black-headed Grosbeak | Pheucticus melanocephalus | Cardinals and Allies | 3,428 | Apr (past peak) |
| 32 | Ash-throated Flycatcher | Myiarchus cinerascens | Tyrant Flycatchers | 3,272 | May (peak) |
| 33 | Great Egret | Ardea alba | Herons, Egrets, and Bitterns | 3,267 | Jan (past peak) |
| 34 | Bushtit | Psaltriparus minimus | Long-tailed Tits and Bushtits | 3,129 | Apr (past peak) |
| 35 | Great Horned Owl | Bubo virginianus | Typical Owls | 3,082 | Apr (past peak) |
| 36 | Western Tanager | Piranga ludoviciana | Cardinals and Allies | 3,065 | May (peak) |
| 37 | Steller's Jay | Cyanocitta stelleri | Crows, Jays, and Magpies | 3,037 | Jul (rising) |
| 38 | Red-shouldered Hawk | Buteo lineatus | Hawks, Eagles, and Kites | 2,960 | Jan (past peak) |
| 39 | Killdeer | Charadrius vociferus | Plovers and Lapwings | 2,791 | Apr (past peak) |
| 40 | Double-crested Cormorant | Nannopterum auritum | Cormorants and Shags | 2,747 | Jan (past peak) |
| 41 | Brewer's Blackbird | Euphagus cyanocephalus | New World Blackbirds and Orioles | 2,534 | Apr (past peak) |
| 42 | Cliff Swallow | Petrochelidon pyrrhonota | Swallows and Martins | 2,524 | Apr (past peak) |
| 43 | European Starling | Sturnus vulgaris | Starlings | 2,520 | Apr (past peak) |
| 44 | Allen's Hummingbird | Selasphorus sasin | Hummingbirds | 2,488 | Apr (past peak) |
| 45 | Western Kingbird | Tyrannus verticalis | Tyrant Flycatchers | 2,335 | Apr (past peak) |
| 46 | Barn Swallow | Hirundo rustica | Swallows and Martins | 2,298 | May (peak) |
| 47 | Tree Swallow | Tachycineta bicolor | Swallows and Martins | 2,296 | Apr (past peak) |
| 48 | Cooper's Hawk | Astur cooperii | Hawks, Eagles, and Kites | 2,256 | Jul (rising) |
| 49 | Great-tailed Grackle | Quiscalus mexicanus | New World Blackbirds and Orioles | 2,068 | Apr (past peak) |
| 50 | Osprey | Pandion haliaetus | Ospreys | 2,041 | Jul (rising) |