WhenToBird

Gavia stellata · Gaviidae

When Do Red-throated Loons Arrive in California?

Adult Red-throated Loon
Photo: Elizabeth Green, CC BY 4.0 via iNaturalist

Red-throated Loons are winter birds in California: they arrive in early November, peak in early December (2.4% of checklists), and most are gone by late April.

When to look

First arrivalsNov 1-7early November
Common byNov 1-7early November
PeakDec 1-7early December
Most gone byApr 22-30late April

Best: early December. First arrivals early November; most are gone by late April. Peak: on about 2.4% of California checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Jununcommon
  7. Julrare
  8. Auguncommon
  9. Sepuncommon
  10. Octuncommon
  11. Novpeak season
  12. Decpeak season

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

0%1%2%3%Jan 1-7: 1.7% of 112336 checklistsJan 8-14: 1.9% of 85518 checklistsJan 15-21: 1.9% of 86488 checklistsJan 22-31: 2.1% of 116174 checklistsFeb 1-7: 1.9% of 75171 checklistsFeb 8-14: 1.8% of 84467 checklistsFeb 15-21: 1.6% of 105683 checklistsFeb 22-28: 2.1% of 83396 checklistsMar 1-7: 2.1% of 77470 checklistsMar 8-14: 2.1% of 75180 checklistsMar 15-21: 1.9% of 80770 checklistsMar 22-31: 1.5% of 114116 checklistsApr 1-7: 1.3% of 84057 checklistsApr 8-14: 1.2% of 83692 checklistsApr 15-21: 1.2% of 89242 checklistsApr 22-30: 1.0% of 114289 checklistsMay 1-7: 0.9% of 85728 checklistsMay 8-14: 0.6% of 91984 checklistsMay 15-21: 0.6% of 75478 checklistsMay 22-31: 0.6% of 106250 checklistsJun 1-7: 0.4% of 70051 checklistsJun 8-14: 0.4% of 67485 checklistsJun 15-21: 0.3% of 66269 checklistsJun 22-30: 0.4% of 79172 checklistsJul 1-7: 0.3% of 62877 checklistsJul 8-14: 0.3% of 60328 checklistsJul 15-21: 0.2% of 59705 checklistsJul 22-31: 0.3% of 83796 checklistsAug 1-7: 0.3% of 60215 checklistsAug 8-14: 0.3% of 60172 checklistsAug 15-21: 0.2% of 59877 checklistsAug 22-31: 0.4% of 89107 checklistsSep 1-7: 0.5% of 72000 checklistsSep 8-14: 0.4% of 71228 checklistsSep 15-21: 0.4% of 76808 checklistsSep 22-30: 0.4% of 100204 checklistsOct 1-7: 0.4% of 76571 checklistsOct 8-14: 0.5% of 80874 checklistsOct 15-21: 0.6% of 74581 checklistsOct 22-31: 0.7% of 97498 checklistsNov 1-7: 1.4% of 70851 checklistsNov 8-14: 1.8% of 72431 checklistsNov 15-21: 2.2% of 66767 checklistsNov 22-30: 2.3% of 94737 checklistsDec 1-7: 2.4% of 65393 checklistsDec 8-14: 2.4% of 67449 checklistsDec 15-21: 1.8% of 83421 checklistsDec 22-31: 1.7% 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.

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Where in California

Best counties

Share of checklists at the peak
  1. Monterey CountyBest early December · 2617 checklists that week, 132,505 in all23%
  2. Del Norte CountyBest the second week of March · 225 checklists that week, 16,363 in all12%
  3. Humboldt CountyBest early January · 3106 checklists that week, 95,963 in all7.2%
  4. Marin CountyBest late January · 3954 checklists that week, 135,728 in all7.2%
  5. San Francisco CountyBest early March · 2379 checklists that week, 130,018 in all6.9%
  6. Santa Cruz CountyBest early March · 2627 checklists that week, 140,819 in all6.7%

Best spots

Share of checklists at the peak
  1. San Francisco ZooSan Francisco County, best late November · 35 checklists that week, 883 in all94%
  2. Rodeo LagoonMarin County, best early March · 83 checklists that week, 5,666 in all75%
  3. Crespi PondMonterey County, best late November · 1044 checklists that week, 7,637 in all74%
  4. Golden Gate National Recreation Area (Helmet Rock)San Francisco County, best late January · 24 checklists that week, 1,294 in all72%

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

Best time of day

In California, the Red-throated Loon is most often listed on checklists started between 6 and 8 am (1.4% of those checklists).

0%0.5%1%1.5%2%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: 1.1% of 186053 checklists7 am: 1.5% of 444086 checklists8 am: 1.2% of 535846 checklists9 am: 1.3% of 486061 checklists10 am: 1.3% of 411130 checklists11 am: 1.3% of 325798 checklists12 pm: 1.2% of 269132 checklists1 pm: 1.2% of 244762 checklists2 pm: 1.1% of 235420 checklists3 pm: 1.0% of 232365 checklists4 pm: 0.8% of 208688 checklists5 pm: 0.5% of 146104 checklists6 pm: 0.4% 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
January1.7%1.9%1.9%2.1%
February1.9%1.8%1.6%2.1%
March2.1%2.1%1.9%1.5%
April1.3%1.2%1.2%1.0%
May0.9%0.6%0.6%0.6%
June0.4%0.4%0.3%0.4%
July0.3%0.3%0.2%0.3%
August0.3%0.3%0.2%0.4%
September0.5%0.4%0.4%0.4%
October0.4%0.5%0.6%0.7%
November1.4%1.8%2.2%2.3%
December2.4%2.4%1.8%1.7%

Neighboring states

  • Oregon: arrives late August, 9 weeks earlier than California
  • Washington: arrives late September, 5 weeks earlier than California
  • South Carolina: arrives early December, 4 weeks later than California
  • Alaska: arrives late April, 23 weeks later than California

Common questions

When do Red-throated Loons arrive in California?
Red-throated Loons are winter birds in California: they arrive in early November, peak in early December (2.4% of checklists), and most are gone by late April.
When do Red-throated Loons leave California?
Most Red-throated Loons have left California by late April, when reports fall below half their usual rate.
When is the best time to see a Red-throated Loon in California?
The Red-throated Loon is reported most often in early December, on about 2.4% of California checklists.
Where in California are Red-throated Loons seen most often?
By county, Monterey County, Del Norte County, and Humboldt County have the highest peak reporting rates for the Red-throated Loon (counties with at least 200 checklists).