WhenToBird

Falco columbarius · Falconidae

When Do Merlins Arrive in California?

Adult female Merlin
Photo: Cricket Raspet, CC BY 4.0 via iNaturalist

Merlins are winter birds in California: they arrive in late September, peak in the second week of December (2.7% of checklists), and most are gone by late March.

When to look

First arrivalsSep 22-30late September
Common bySep 22-30late September
PeakDec 8-14the second week of December
Most gone byMar 22-31late March

Best: the second week of December. First arrivals late September; most are gone by late March. Peak: on about 2.7% of California checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Apruncommon
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepuncommon
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%1%2%3%Jan 1-7: 2.4% of 112336 checklistsJan 8-14: 2.4% of 85518 checklistsJan 15-21: 2.5% of 86488 checklistsJan 22-31: 2.1% of 116174 checklistsFeb 1-7: 2.0% of 75171 checklistsFeb 8-14: 1.8% of 84467 checklistsFeb 15-21: 1.5% of 105683 checklistsFeb 22-28: 1.6% of 83396 checklistsMar 1-7: 1.6% of 77470 checklistsMar 8-14: 1.4% of 75180 checklistsMar 15-21: 1.4% of 80770 checklistsMar 22-31: 1.2% of 114116 checklistsApr 1-7: 0.9% of 84057 checklistsApr 8-14: 0.7% of 83692 checklistsApr 15-21: 0.5% of 89242 checklistsApr 22-30: 0.3% of 114289 checklistsMay 1-7: 0.1% of 85728 checklistsMay 8-14: 0.1% of 91984 checklistsMay 15-21: 0.1% of 75478 checklistsMay 22-31: 0.1% of 106250 checklistsJun 1-7: 0.1% of 70051 checklistsJun 8-14: 0% of 67485 checklistsJun 15-21: 0.1% of 66269 checklistsJun 22-30: 0.1% of 79172 checklistsJul 1-7: 0.1% of 62877 checklistsJul 8-14: 0% of 60328 checklistsJul 15-21: 0.1% of 59705 checklistsJul 22-31: 0.1% of 83796 checklistsAug 1-7: 0.1% of 60215 checklistsAug 8-14: 0.1% of 60172 checklistsAug 15-21: 0.1% of 59877 checklistsAug 22-31: 0.1% of 89107 checklistsSep 1-7: 0.1% of 72000 checklistsSep 8-14: 0.3% of 71228 checklistsSep 15-21: 0.6% of 76808 checklistsSep 22-30: 1.1% of 100204 checklistsOct 1-7: 1.4% of 76571 checklistsOct 8-14: 1.5% of 80874 checklistsOct 15-21: 1.8% of 74581 checklistsOct 22-31: 2.4% of 97498 checklistsNov 1-7: 2.7% of 70851 checklistsNov 8-14: 2.6% of 72431 checklistsNov 15-21: 2.7% of 66767 checklistsNov 22-30: 2.5% of 94737 checklistsDec 1-7: 2.7% of 65393 checklistsDec 8-14: 2.6% of 67449 checklistsDec 15-21: 2.7% of 83421 checklistsDec 22-31: 2.3% 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. Glenn CountyBest the second week of December · 137 checklists that week, 5,189 in all9.0%
  2. Napa CountyBest early November · 323 checklists that week, 18,976 in all8.2%
  3. Humboldt CountyBest early November · 1703 checklists that week, 95,963 in all5.8%
  4. Kings CountyBest the second week of November · 55 checklists that week, 3,688 in all5.7%
  5. Mendocino CountyBest late January · 1300 checklists that week, 47,934 in all5.4%
  6. Alpine CountyBest early November · 38 checklists that week, 6,013 in all5.3%

Best spots

Share of checklists at the peak
  1. Kirby CoveMarin County, best late October · 73 checklists that week, 1,041 in all41%
  2. Riverside ParkMendocino County, best mid November · 25 checklists that week, 1,220 in all36%
  3. San Luis Rey River TrailSan Diego County, best early November · 39 checklists that week, 983 in all34%
  4. Don Edwards San Francisco Bay National Wildlife Refuge (Albrae)Alameda County, best the second week of November · 26 checklists that week, 874 in all33%

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

Best time of day

In California, the Merlin is most often listed on checklists started between 7 and 9 am (1.6% 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: 1.0% of 186053 checklists7 am: 1.7% of 444086 checklists8 am: 1.6% of 535846 checklists9 am: 1.2% of 486061 checklists10 am: 1.1% of 411130 checklists11 am: 1.0% of 325798 checklists12 pm: 1.0% of 269132 checklists1 pm: 1.1% of 244762 checklists2 pm: 1.3% of 235420 checklists3 pm: 1.4% of 232365 checklists4 pm: 1.1% of 208688 checklists5 pm: 0.6% of 146104 checklists6 pm: 0.3% 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
January2.4%2.4%2.5%2.1%
February2.0%1.8%1.5%1.6%
March1.6%1.4%1.4%1.2%
April0.9%0.7%0.5%0.3%
May0.1%0.1%0.1%0.1%
June0.1%0%0.1%0.1%
July0.1%0%0.1%0.1%
August0.1%0.1%0.1%0.1%
September0.1%0.3%0.6%1.1%
October1.4%1.5%1.8%2.4%
November2.7%2.6%2.7%2.5%
December2.7%2.6%2.7%2.3%

Neighboring states

  • Nevada: arrives late September, in the same week than California
  • Utah: arrives the second week of October, 2 weeks later than California
  • Arizona: arrives late September, in the same week than California
  • Oregon: arrives mid September, 1 week earlier than California

Common questions

When do Merlins arrive in California?
Merlins are winter birds in California: they arrive in late September, peak in the second week of December (2.7% of checklists), and most are gone by late March.
When do Merlins leave California?
Most Merlins have left California by late March, when reports fall below half their usual rate.
When is the best time to see a Merlin in California?
The Merlin is reported most often in the second week of December, on about 2.7% of California checklists.
Where in California are Merlins seen most often?
By county, Glenn County, Napa County, and Humboldt County have the highest peak reporting rates for the Merlin (counties with at least 200 checklists).