WhenToBird

Polioptila caerulea · Polioptilidae

When Do Blue-gray Gnatcatchers Arrive in California?

Adult Blue-gray Gnatcatcher
Photo: Laura Clark, CC BY 4.0 via iNaturalist

Blue-gray Gnatcatchers are in California all year, but most are here in fall: numbers build from early September, peak in the second week of November (5.7% of checklists), and fall back by late January. In the quietest week (mid July) they are still on about 2.2% of checklists.

When to look

Numbers buildSep 1-7early September
PeakNov 8-14the second week of November
Fall back byJan 22-31late January
FewestJul 15-21mid July

Best: the second week of November. Here all year; numbers build from early September and fall back by late January. Peak: on about 5.7% of California checklists.

  1. Janpeak season
  2. Febcommon
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Seppeak season
  10. Octpeak season
  11. Novpeak season
  12. Decpeak season

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

0%2%4%6%Jan 1-7: 5.3% of 112336 checklistsJan 8-14: 4.7% of 85518 checklistsJan 15-21: 4.7% of 86488 checklistsJan 22-31: 4.2% of 116174 checklistsFeb 1-7: 3.8% of 75171 checklistsFeb 8-14: 3.4% of 84467 checklistsFeb 15-21: 3.2% of 105683 checklistsFeb 22-28: 3.6% of 83396 checklistsMar 1-7: 3.4% of 77470 checklistsMar 8-14: 3.2% of 75180 checklistsMar 15-21: 3.5% of 80770 checklistsMar 22-31: 3.7% of 114116 checklistsApr 1-7: 4.2% of 84057 checklistsApr 8-14: 4.7% of 83692 checklistsApr 15-21: 5.3% of 89242 checklistsApr 22-30: 5.0% of 114289 checklistsMay 1-7: 4.7% of 85728 checklistsMay 8-14: 4.3% of 91984 checklistsMay 15-21: 4.4% of 75478 checklistsMay 22-31: 4.3% of 106250 checklistsJun 1-7: 3.8% of 70051 checklistsJun 8-14: 3.5% of 67485 checklistsJun 15-21: 3.4% of 66269 checklistsJun 22-30: 3.1% of 79172 checklistsJul 1-7: 2.9% of 62877 checklistsJul 8-14: 2.3% of 60328 checklistsJul 15-21: 2.2% of 59705 checklistsJul 22-31: 2.1% of 83796 checklistsAug 1-7: 2.5% of 60215 checklistsAug 8-14: 2.8% of 60172 checklistsAug 15-21: 3.1% of 59877 checklistsAug 22-31: 3.6% of 89107 checklistsSep 1-7: 4.1% of 72000 checklistsSep 8-14: 4.8% of 71228 checklistsSep 15-21: 5.4% of 76808 checklistsSep 22-30: 5.7% of 100204 checklistsOct 1-7: 5.8% of 76571 checklistsOct 8-14: 5.4% of 80874 checklistsOct 15-21: 5.5% of 74581 checklistsOct 22-31: 5.5% of 97498 checklistsNov 1-7: 5.8% of 70851 checklistsNov 8-14: 5.8% of 72431 checklistsNov 15-21: 5.6% of 66767 checklistsNov 22-30: 5.7% of 94737 checklistsDec 1-7: 5.7% of 65393 checklistsDec 8-14: 5.3% of 67449 checklistsDec 15-21: 5.1% of 83421 checklistsDec 22-31: 5.3% 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. Ventura CountyBest mid November · 1404 checklists that week, 94,391 in all21%
  2. Orange CountyBest the second week of October · 4867 checklists that week, 244,559 in all19%
  3. Santa Barbara CountyBest mid November · 2249 checklists that week, 120,616 in all18%
  4. Inyo CountyBest early May · 1026 checklists that week, 35,713 in all15%
  5. Imperial CountyBest mid December · 985 checklists that week, 24,551 in all14%
  6. San Luis Obispo CountyBest early November · 2360 checklists that week, 124,667 in all13%

Best spots

Share of checklists at the peak
  1. Auburn State Recreation AreaPlacer County, best mid April · 30 checklists that week, 228 in all91%
  2. Willow Springs ParkLos Angeles County, best early January · 21 checklists that week, 832 in all90%
  3. Harmony Headlands State ParkSan Luis Obispo County, best the second week of January · 20 checklists that week, 681 in all85%
  4. Auburn State Recreation Area (New York Bar)Placer County, best late May · 23 checklists that week, 193 in all85%
  5. San Luis Rey River TrailSan Diego County, best early November · 39 checklists that week, 983 in all83%
  6. Peck Road ParkLos Angeles County, best mid November · 56 checklists that week, 3,102 in all82%

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

Best time of day

In California, the Blue-gray Gnatcatcher is most often listed on checklists started between 6 and 8 am (6.6% of those checklists).

0%2%4%6%8%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: 6.5% of 186053 checklists7 am: 6.7% of 444086 checklists8 am: 6.0% of 535846 checklists9 am: 4.9% of 486061 checklists10 am: 4.4% of 411130 checklists11 am: 3.7% of 325798 checklists12 pm: 3.3% of 269132 checklists1 pm: 3.1% of 244762 checklists2 pm: 3.1% of 235420 checklists3 pm: 2.9% of 232365 checklists4 pm: 2.3% of 208688 checklists5 pm: 2.3% of 146104 checklists6 pm: 1.9% 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
January5.3%4.7%4.7%4.2%
February3.8%3.4%3.2%3.6%
March3.4%3.2%3.5%3.7%
April4.2%4.7%5.3%5.0%
May4.7%4.3%4.4%4.3%
June3.8%3.5%3.4%3.1%
July2.9%2.3%2.2%2.1%
August2.5%2.8%3.1%3.6%
September4.1%4.8%5.4%5.7%
October5.8%5.4%5.5%5.5%
November5.8%5.8%5.6%5.7%
December5.7%5.3%5.1%5.3%

Neighboring states

  • Nevada: arrives late March, 21 weeks earlier than California
  • Utah: arrives early April, 20 weeks earlier than California
  • Arizona: year-round, peaks early December
  • Idaho: arrives early May, 16 weeks earlier than California

Common questions

When do Blue-gray Gnatcatchers arrive in California?
Blue-gray Gnatcatchers are in California all year, but most are here in fall: numbers build from early September, peak in the second week of November (5.7% of checklists), and fall back by late January. In the quietest week (mid July) they are still on about 2.2% of checklists.
When do Blue-gray Gnatcatchers leave California?
Blue-gray Gnatcatchers never fully leave California: numbers fall back below half their usual rate by late January, but some are still reported in every week, about 2.2% of checklists at the low.
When is the best time to see a Blue-gray Gnatcatcher in California?
The Blue-gray Gnatcatcher is reported most often in the second week of November, on about 5.7% of California checklists.
Where in California are Blue-gray Gnatcatchers seen most often?
By county, Ventura County, Orange County, and Santa Barbara County have the highest peak reporting rates for the Blue-gray Gnatcatcher (counties with at least 200 checklists).