WhenToBird

Gavia pacifica · Gaviidae

When Do Pacific Loons Arrive in California?

Adult Pacific Loon
Photo: Bob Miller, CC BY 4.0 via iNaturalist

Pacific Loons are winter birds in California: they arrive in the second week of October, peak in late November (2.2% of checklists), and most are gone by early June.

When to look

First arrivalsOct 8-14the second week of October
Common byOct 8-14the second week of October
PeakNov 22-30late November
Most gone byJun 1-7early June

Best: late November. First arrivals the second week of October; most are gone by early June. Peak: on about 2.2% of California checklists.

  1. Jancommon
  2. Febuncommon
  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%1%2%3%Jan 1-7: 1.1% of 112336 checklistsJan 8-14: 1.0% of 85518 checklistsJan 15-21: 1.0% of 86488 checklistsJan 22-31: 0.9% of 116174 checklistsFeb 1-7: 0.8% of 75171 checklistsFeb 8-14: 0.8% of 84467 checklistsFeb 15-21: 0.7% of 105683 checklistsFeb 22-28: 0.9% of 83396 checklistsMar 1-7: 0.9% of 77470 checklistsMar 8-14: 0.9% of 75180 checklistsMar 15-21: 0.9% of 80770 checklistsMar 22-31: 0.7% of 114116 checklistsApr 1-7: 0.7% of 84057 checklistsApr 8-14: 0.8% of 83692 checklistsApr 15-21: 1.0% of 89242 checklistsApr 22-30: 1.1% of 114289 checklistsMay 1-7: 1.3% of 85728 checklistsMay 8-14: 1.0% of 91984 checklistsMay 15-21: 1.0% of 75478 checklistsMay 22-31: 0.9% of 106250 checklistsJun 1-7: 0.6% of 70051 checklistsJun 8-14: 0.4% of 67485 checklistsJun 15-21: 0.3% of 66269 checklistsJun 22-30: 0.3% of 79172 checklistsJul 1-7: 0.3% of 62877 checklistsJul 8-14: 0.3% of 60328 checklistsJul 15-21: 0.3% of 59705 checklistsJul 22-31: 0.4% of 83796 checklistsAug 1-7: 0.4% of 60215 checklistsAug 8-14: 0.5% of 60172 checklistsAug 15-21: 0.5% of 59877 checklistsAug 22-31: 0.5% of 89107 checklistsSep 1-7: 0.5% of 72000 checklistsSep 8-14: 0.5% of 71228 checklistsSep 15-21: 0.5% of 76808 checklistsSep 22-30: 0.4% of 100204 checklistsOct 1-7: 0.5% of 76571 checklistsOct 8-14: 0.5% of 80874 checklistsOct 15-21: 0.6% of 74581 checklistsOct 22-31: 0.8% of 97498 checklistsNov 1-7: 1.8% of 70851 checklistsNov 8-14: 1.9% of 72431 checklistsNov 15-21: 2.2% of 66767 checklistsNov 22-30: 2.4% of 94737 checklistsDec 1-7: 2.1% of 65393 checklistsDec 8-14: 1.9% of 67449 checklistsDec 15-21: 1.1% of 83421 checklistsDec 22-31: 1.1% 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 all29%
  2. Del Norte CountyBest early August · 314 checklists that week, 16,363 in all6.9%
  3. Mendocino CountyBest mid November · 752 checklists that week, 47,934 in all6.1%
  4. Humboldt CountyBest the second week of November · 1618 checklists that week, 95,963 in all5.4%
  5. Marin CountyBest late May · 4004 checklists that week, 135,728 in all4.8%
  6. Santa Barbara CountyBest mid April · 2697 checklists that week, 120,616 in all3.6%

Best spots

Share of checklists at the peak
  1. Crespi PondMonterey County, best late November · 1044 checklists that week, 7,637 in all89%
  2. Point ArenaMendocino County, best early January · 21 checklists that week, 249 in all78%
  3. Pigeon PointSan Mateo County, best early May · 45 checklists that week, 1,303 in all72%
  4. San Francisco ZooSan Francisco County, best the second week of October · 20 checklists that week, 883 in all67%
  5. Piedras Blancas Outstanding Natural AreaSan Luis Obispo County, best the second week of April · 25 checklists that week, 119 in all66%

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

Best time of day

In California, the Pacific Loon is most often listed on checklists started between 6 and 8 am (1.1% of those checklists).

0%0.5%1%1.5%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: 1.0% of 444086 checklists8 am: 0.9% of 535846 checklists9 am: 1.0% of 486061 checklists10 am: 1.0% of 411130 checklists11 am: 1.0% of 325798 checklists12 pm: 1.0% of 269132 checklists1 pm: 0.9% of 244762 checklists2 pm: 0.9% of 235420 checklists3 pm: 0.8% of 232365 checklists4 pm: 0.7% 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
January1.1%1.0%1.0%0.9%
February0.8%0.8%0.7%0.9%
March0.9%0.9%0.9%0.7%
April0.7%0.8%1.0%1.1%
May1.3%1.0%1.0%0.9%
June0.6%0.4%0.3%0.3%
July0.3%0.3%0.3%0.4%
August0.4%0.5%0.5%0.5%
September0.5%0.5%0.5%0.4%
October0.5%0.5%0.6%0.8%
November1.8%1.9%2.2%2.4%
December2.1%1.9%1.1%1.1%

Neighboring states

  • Oregon: arrives late June, 14 weeks earlier than California
  • Idaho: arrives mid October, 1 week later than California
  • Washington: arrives mid September, 3 weeks earlier than California
  • Colorado: arrives mid October, 1 week later than California

Common questions

When do Pacific Loons arrive in California?
Pacific Loons are winter birds in California: they arrive in the second week of October, peak in late November (2.2% of checklists), and most are gone by early June.
When do Pacific Loons leave California?
Most Pacific Loons have left California by early June, when reports fall below half their usual rate.
When is the best time to see a Pacific Loon in California?
The Pacific Loon is reported most often in late November, on about 2.2% of California checklists.
Where in California are Pacific Loons seen most often?
By county, Monterey County, Del Norte County, and Mendocino County have the highest peak reporting rates for the Pacific Loon (counties with at least 200 checklists).