WhenToBird

Gavia immer · Gaviidae

When Do Common Loons Arrive in California?

Adult Common Loon
Photo: Hungry-Sarracenia Photo, CC BY 4.0 via iNaturalist

Common Loons are winter birds in California: the first arrive in late September, they are common by the second week of October, peak in mid November (4.0% of checklists), and most are gone by late May.

When to look

First arrivalsSep 22-30late September
Common byOct 8-14the second week of October
PeakNov 15-21mid November
Most gone byMay 22-31late May

Best: mid November. First arrivals late September; most are gone by late May. Peak: on about 4.0% of California checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Aprcommon
  5. Maycommon
  6. Jununcommon
  7. Juluncommon
  8. Auguncommon
  9. Sepuncommon
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

Darker months: more checklists report it. Outlined: peak month.

0%2%4%6%Jan 1-7: 3.1% of 112336 checklistsJan 8-14: 3.4% of 85518 checklistsJan 15-21: 3.4% of 86488 checklistsJan 22-31: 2.9% of 116174 checklistsFeb 1-7: 2.7% of 75171 checklistsFeb 8-14: 2.4% of 84467 checklistsFeb 15-21: 2.1% of 105683 checklistsFeb 22-28: 2.6% of 83396 checklistsMar 1-7: 2.4% of 77470 checklistsMar 8-14: 2.5% of 75180 checklistsMar 15-21: 2.3% of 80770 checklistsMar 22-31: 2.2% of 114116 checklistsApr 1-7: 2.1% of 84057 checklistsApr 8-14: 2.1% of 83692 checklistsApr 15-21: 2.3% of 89242 checklistsApr 22-30: 2.0% of 114289 checklistsMay 1-7: 1.9% of 85728 checklistsMay 8-14: 1.5% of 91984 checklistsMay 15-21: 1.4% of 75478 checklistsMay 22-31: 1.2% of 106250 checklistsJun 1-7: 1.0% of 70051 checklistsJun 8-14: 0.9% of 67485 checklistsJun 15-21: 0.9% of 66269 checklistsJun 22-30: 0.9% of 79172 checklistsJul 1-7: 0.9% of 62877 checklistsJul 8-14: 0.9% of 60328 checklistsJul 15-21: 0.7% of 59705 checklistsJul 22-31: 0.8% of 83796 checklistsAug 1-7: 0.8% of 60215 checklistsAug 8-14: 0.9% of 60172 checklistsAug 15-21: 0.8% of 59877 checklistsAug 22-31: 0.8% of 89107 checklistsSep 1-7: 0.8% of 72000 checklistsSep 8-14: 0.8% of 71228 checklistsSep 15-21: 0.9% of 76808 checklistsSep 22-30: 1.0% of 100204 checklistsOct 1-7: 1.2% of 76571 checklistsOct 8-14: 1.3% of 80874 checklistsOct 15-21: 1.8% of 74581 checklistsOct 22-31: 2.4% of 97498 checklistsNov 1-7: 3.5% of 70851 checklistsNov 8-14: 3.9% of 72431 checklistsNov 15-21: 4.1% of 66767 checklistsNov 22-30: 3.9% of 94737 checklistsDec 1-7: 3.5% of 65393 checklistsDec 8-14: 3.4% of 67449 checklistsDec 15-21: 2.7% of 83421 checklistsDec 22-31: 3.0% of 124993 checklistsJanFebMarAprMayJunJulAugSepOctNovDec
Share of complete checklists reporting it, by week (4 per month). Grey bars: fewer than 10 checklists, not counted.

Frequency is the share of complete checklists in California that listed the bird, 2016–2025. It is not a head count, and it follows where and when people go birding. How to read it.

JanFebMarAprMayJunJulAugSepOctNovDec
today
Second week of November

Each county is shaded by the share of complete checklists there that listed the bird, blended with the weeks either side. Darker is more often. It follows where people watch birds, not how many birds there are. How to read it.

Embed this map on your site

Where in California

Best counties

Share of checklists at the peak
  1. Monterey CountyBest the second week of November · 3190 checklists that week, 132,505 in all19%
  2. Del Norte CountyBest early March · 175 checklists that week, 16,363 in all17%
  3. Plumas CountyBest the second week of November · 285 checklists that week, 24,629 in all16%
  4. Sierra CountyBest early November · 66 checklists that week, 8,945 in all16%
  5. Mono CountyBest late November · 339 checklists that week, 38,666 in all13%
  6. Humboldt CountyBest the second week of November · 1618 checklists that week, 95,963 in all13%

Best spots

Share of checklists at the peak
  1. Buhne PointHumboldt County, best mid April · 29 checklists that week, 1,048 in all98%
  2. Bodega HarborSonoma County, best the second week of March · 20 checklists that week, 1,051 in all96%
  3. Bodega Harbor (Bodega Bay)Sonoma County, best the second week of March · 24 checklists that week, 895 in all93%
  4. Spud PointSonoma County, best late March · 31 checklists that week, 735 in all90%
  5. Point Reyes National SeashoreMarin County, best mid March · 27 checklists that week, 3,522 in all88%

Busy spots report more of everything; compare the checklist counts before you drive anywhere.

Best time of day

In California, the Common Loon is most often listed on checklists started between 12 and 2 pm (2.4% of those checklists).

0%1%2%3%12 am: too few checklists (1688) to judge1 am: too few checklists (1451) to judge2 am: too few checklists (1402) to judge3 am: too few checklists (1743) to judge4 am: too few checklists (4647) to judge5 am: too few checklists (32158) to judge6 am: 1.7% of 186053 checklists7 am: 2.0% of 444086 checklists8 am: 2.0% of 535846 checklists9 am: 2.2% of 486061 checklists10 am: 2.3% of 411130 checklists11 am: 2.4% of 325798 checklists12 pm: 2.4% of 269132 checklists1 pm: 2.5% of 244762 checklists2 pm: 2.3% of 235420 checklists3 pm: 2.1% of 232365 checklists4 pm: 1.6% of 208688 checklists5 pm: 1.1% of 146104 checklists6 pm: 0.9% of 96867 checklists7 pm: too few checklists (50942) to judge8 pm: too few checklists (14803) to judge9 pm: too few checklists (5561) to judge10 pm: too few checklists (3546) to judge11 pm: too few checklists (2092) to judge12a3a6a9a12p3p6p9p
Share of checklists started in each local hour that reported it. It reflects when people go birding as well as when birds are active. Grey hours have too few checklists (under 2% of the state’s, or under 200) to judge.
Week-by-week table
MonthDays 1-78-1415-2122-end
January3.1%3.4%3.4%2.9%
February2.7%2.4%2.1%2.6%
March2.4%2.5%2.3%2.2%
April2.1%2.1%2.3%2.0%
May1.9%1.5%1.4%1.2%
June1.0%0.9%0.9%0.9%
July0.9%0.9%0.7%0.8%
August0.8%0.9%0.8%0.8%
September0.8%0.8%0.9%1.0%
October1.2%1.3%1.8%2.4%
November3.5%3.9%4.1%3.9%
December3.5%3.4%2.7%3.0%

Neighboring states

  • Nevada: arrives the second week of October, 2 weeks later than California
  • Utah: arrives early October, 1 week later than California
  • Oregon: arrives early September, 3 weeks earlier than California
  • Idaho: arrives early September, 3 weeks earlier than California

Common questions

When do Common Loons arrive in California?
Common Loons are winter birds in California: the first arrive in late September, they are common by the second week of October, peak in mid November (4.0% of checklists), and most are gone by late May.
When do Common Loons leave California?
Most Common Loons have left California by late May, when reports fall below half their usual rate. Stragglers are still reported until early June.
When is the best time to see a Common Loon in California?
The Common Loon is reported most often in mid November, on about 4.0% of California checklists.
Where in California are Common Loons seen most often?
By county, Monterey County, Del Norte County, and Plumas County have the highest peak reporting rates for the Common Loon (counties with at least 200 checklists).