WhenToBird

Passerella iliaca · Passerellidae

When Do Fox Sparrows Arrive in California?

Adult Fox Sparrow
Photo: Kevin Krebs, CC BY 4.0 via iNaturalist

Fox Sparrows are winter birds in California: the first arrive in the second week of September, they are common by mid September, peak in the second week of October (7.9% of checklists), and most are gone by the second week of April.

When to look

First arrivalsSep 8-14the second week of September
Common bySep 15-21mid September
PeakOct 8-14the second week of October
Most gone byApr 8-14the second week of April

Best: the second week of October. First arrivals the second week of September; most are gone by the second week of April. Peak: on about 7.9% of California checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Aprcommon
  5. Mayuncommon
  6. Jununcommon
  7. Juluncommon
  8. Augrare
  9. Sepcommon
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%5%10%Jan 1-7: 6.9% of 112336 checklistsJan 8-14: 6.0% of 85518 checklistsJan 15-21: 5.8% of 86488 checklistsJan 22-31: 5.7% of 116174 checklistsFeb 1-7: 5.4% of 75171 checklistsFeb 8-14: 5.0% of 84467 checklistsFeb 15-21: 4.8% of 105683 checklistsFeb 22-28: 5.1% of 83396 checklistsMar 1-7: 5.2% of 77470 checklistsMar 8-14: 4.8% of 75180 checklistsMar 15-21: 4.5% of 80770 checklistsMar 22-31: 4.1% of 114116 checklistsApr 1-7: 3.5% of 84057 checklistsApr 8-14: 2.6% of 83692 checklistsApr 15-21: 1.7% of 89242 checklistsApr 22-30: 1.0% of 114289 checklistsMay 1-7: 0.7% of 85728 checklistsMay 8-14: 0.9% of 91984 checklistsMay 15-21: 1.2% of 75478 checklistsMay 22-31: 1.8% of 106250 checklistsJun 1-7: 2.4% of 70051 checklistsJun 8-14: 2.9% of 67485 checklistsJun 15-21: 3.3% of 66269 checklistsJun 22-30: 3.2% of 79172 checklistsJul 1-7: 2.4% of 62877 checklistsJul 8-14: 2.1% of 60328 checklistsJul 15-21: 1.7% of 59705 checklistsJul 22-31: 1.1% of 83796 checklistsAug 1-7: 0.7% of 60215 checklistsAug 8-14: 0.6% of 60172 checklistsAug 15-21: 0.4% of 59877 checklistsAug 22-31: 0.4% of 89107 checklistsSep 1-7: 0.4% of 72000 checklistsSep 8-14: 1.2% of 71228 checklistsSep 15-21: 2.7% of 76808 checklistsSep 22-30: 5.8% of 100204 checklistsOct 1-7: 7.9% of 76571 checklistsOct 8-14: 7.7% of 80874 checklistsOct 15-21: 8.1% of 74581 checklistsOct 22-31: 7.8% of 97498 checklistsNov 1-7: 7.4% of 70851 checklistsNov 8-14: 7.3% of 72431 checklistsNov 15-21: 7.0% of 66767 checklistsNov 22-30: 7.1% of 94737 checklistsDec 1-7: 7.5% of 65393 checklistsDec 8-14: 7.2% of 67449 checklistsDec 15-21: 7.7% of 83421 checklistsDec 22-31: 7.0% 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.

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Where in California

Best counties

Share of checklists at the peak
  1. Humboldt CountyBest the second week of October · 1962 checklists that week, 95,963 in all37%
  2. San Francisco CountyBest the second week of October · 3155 checklists that week, 130,018 in all32%
  3. Del Norte CountyBest the second week of December · 296 checklists that week, 16,363 in all31%
  4. Fresno CountyBest late June · 724 checklists that week, 29,788 in all28%
  5. Tulare CountyBest mid June · 777 checklists that week, 28,366 in all26%
  6. Sierra CountyBest late June · 833 checklists that week, 8,945 in all25%

Best spots

Share of checklists at the peak
  1. Sand Pond (Lower Sardine Lake)Sierra County, best the second week of June · 37 checklists that week, 157 in all93%
  2. Tilden Regional ParkContra Costa County, best the second week of October · 45 checklists that week, 1,888 in all89%
  3. Arcata Marsh & Wildlife Sanctuary (northeast)Humboldt County, best late November · 36 checklists that week, 1,138 in all88%
  4. Twin Peaks ReservoirSan Francisco County, best early October · 23 checklists that week, 2,067 in all87%
  5. Mountain Lake (Presidio Terrace)San Francisco County, best early January · 23 checklists that week, 114 in all85%

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

Best time of day

In California, the Fox Sparrow is most often listed on checklists started between 7 and 9 am (5.9% of those checklists).

0%2%4%6%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: 3.3% of 186053 checklists7 am: 5.8% of 444086 checklists8 am: 6.0% of 535846 checklists9 am: 5.3% of 486061 checklists10 am: 4.4% of 411130 checklists11 am: 3.8% of 325798 checklists12 pm: 3.6% of 269132 checklists1 pm: 3.5% of 244762 checklists2 pm: 3.3% of 235420 checklists3 pm: 3.3% of 232365 checklists4 pm: 2.9% of 208688 checklists5 pm: 2.1% of 146104 checklists6 pm: 1.3% 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
January6.9%6.0%5.8%5.7%
February5.4%5.0%4.8%5.1%
March5.2%4.8%4.5%4.1%
April3.5%2.6%1.7%1.0%
May0.7%0.9%1.2%1.8%
June2.4%2.9%3.3%3.2%
July2.4%2.1%1.7%1.1%
August0.7%0.6%0.4%0.4%
September0.4%1.2%2.7%5.8%
October7.9%7.7%8.1%7.8%
November7.4%7.3%7.0%7.1%
December7.5%7.2%7.7%7.0%

Neighboring states

  • Nevada: arrives the second week of April, 20 weeks earlier than California
  • Utah: arrives early April, 21 weeks earlier than California
  • Oregon: arrives early September, 1 week earlier than California
  • Idaho: arrives the second week of April, 20 weeks earlier than California

Common questions

When do Fox Sparrows arrive in California?
Fox Sparrows are winter birds in California: the first arrive in the second week of September, they are common by mid September, peak in the second week of October (7.9% of checklists), and most are gone by the second week of April.
When do Fox Sparrows leave California?
Most Fox Sparrows have left California by the second week of April, when reports fall below half their usual rate. Stragglers are still reported until late April.
When is the best time to see a Fox Sparrow in California?
The Fox Sparrow is reported most often in the second week of October, on about 7.9% of California checklists.
Where in California are Fox Sparrows seen most often?
By county, Humboldt County, San Francisco County, and Del Norte County have the highest peak reporting rates for the Fox Sparrow (counties with at least 200 checklists).