WhenToBird

2 loon species in California

When Do Loons Arrive in California?

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

Common Loons and Red-throated Loons are the loons you are most likely to see 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 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.

Loons in California, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
Common LoonSep 22-30Oct 8-14Nov 15-21May 22-314.0%
Red-throated LoonNov 1-7Nov 1-7Dec 1-7Apr 22-302.4%
0%2%4%6%Common LoonRed-throated LoonJanFebMarAprMayJunJulAugSepOctNovDec
  • Common Loon
  • Red-throated Loon
Share of complete checklists reporting each species, by week (4 per month). Gaps: fewer than 10 checklists that week.

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.

Where in California

Best counties for Common Loon

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%

Common questions

When do 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 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 loons in California?
The Common Loon is reported most often in mid November, on about 4.0% of California checklists.
Which loons are in California?
Common Loon and Red-throated Loon are reported regularly; the Common Loon is the most common.