WhenToBird

Vireo bellii · Vireonidae

When Do Bell's Vireos Arrive in California?

Adult male Bell's Vireo
Photo: Pat Farris, CC BY 4.0 via iNaturalist

Bell's Vireos arrive in California in early April, peak in late April (2.5% of checklists), and most are gone by early September.

When to look

First arrivalsApr 1-7early April
Common byApr 1-7early April
PeakApr 22-30late April
Most gone bySep 1-7early September

Best: late April. First arrivals early April; most are gone by early September. Peak: on about 2.5% of California checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Sepcommon
  10. Octnot usually seen
  11. Novnot usually seen
  12. Decnot usually seen

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

0%1%2%3%Jan 1-7: 0.1% of 112336 checklistsJan 8-14: 0.1% of 85518 checklistsJan 15-21: 0.1% of 86488 checklistsJan 22-31: 0.1% of 116174 checklistsFeb 1-7: 0.1% of 75171 checklistsFeb 8-14: 0.1% of 84467 checklistsFeb 15-21: 0.1% of 105683 checklistsFeb 22-28: 0.1% of 83396 checklistsMar 1-7: 0.1% of 77470 checklistsMar 8-14: 0.1% of 75180 checklistsMar 15-21: 0.2% of 80770 checklistsMar 22-31: 0.7% of 114116 checklistsApr 1-7: 1.5% of 84057 checklistsApr 8-14: 2.2% of 83692 checklistsApr 15-21: 2.5% of 89242 checklistsApr 22-30: 2.5% of 114289 checklistsMay 1-7: 2.6% of 85728 checklistsMay 8-14: 2.1% of 91984 checklistsMay 15-21: 2.3% of 75478 checklistsMay 22-31: 2.4% of 106250 checklistsJun 1-7: 2.4% of 70051 checklistsJun 8-14: 2.2% of 67485 checklistsJun 15-21: 2.2% of 66269 checklistsJun 22-30: 2.2% of 79172 checklistsJul 1-7: 2.2% of 62877 checklistsJul 8-14: 1.8% of 60328 checklistsJul 15-21: 1.5% of 59705 checklistsJul 22-31: 1.4% of 83796 checklistsAug 1-7: 1.5% of 60215 checklistsAug 8-14: 1.3% of 60172 checklistsAug 15-21: 1.2% of 59877 checklistsAug 22-31: 1.5% of 89107 checklistsSep 1-7: 1.3% of 72000 checklistsSep 8-14: 0.7% of 71228 checklistsSep 15-21: 0.1% of 76808 checklistsSep 22-30: 0.1% of 100204 checklistsOct 1-7: 0.1% of 76571 checklistsOct 8-14: 0.1% of 80874 checklistsOct 15-21: 0.1% of 74581 checklistsOct 22-31: 0.1% of 97498 checklistsNov 1-7: 0.1% of 70851 checklistsNov 8-14: 0.1% of 72431 checklistsNov 15-21: 0.1% of 66767 checklistsNov 22-30: 0.1% of 94737 checklistsDec 1-7: 0.1% of 65393 checklistsDec 8-14: 0.1% of 67449 checklistsDec 15-21: 0.1% of 83421 checklistsDec 22-31: 0.1% 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. San Bernardino CountyBest late April · 3085 checklists that week, 84,093 in all11%
  2. Orange CountyBest the second week of June · 3729 checklists that week, 244,559 in all9.8%
  3. Riverside CountyBest late June · 1638 checklists that week, 113,541 in all8.8%
  4. San Diego CountyBest late April · 11965 checklists that week, 405,465 in all8.7%
  5. Los Angeles CountyBest early June · 6747 checklists that week, 410,235 in all4.8%
  6. Inyo CountyBest late May · 1654 checklists that week, 35,713 in all4.5%

Best spots

Share of checklists at the peak
  1. Los Cerritos WetlandsOrange County, best mid April · 20 checklists that week, 911 in all97%
  2. Steele CanyonSan Diego County, best late May · 29 checklists that week, 516 in all88%
  3. Tijuana River Valley Regional Park (east)San Diego County, best the second week of June · 36 checklists that week, 3,110 in all85%

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

Best time of day

In California, the Bell's Vireo is most often listed on checklists started between 6 and 8 am (2.1% of those checklists).

0%1%2%3%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: 2.5% of 186053 checklists7 am: 1.9% of 444086 checklists8 am: 1.2% of 535846 checklists9 am: 0.9% of 486061 checklists10 am: 0.6% of 411130 checklists11 am: 0.5% of 325798 checklists12 pm: 0.4% of 269132 checklists1 pm: 0.3% of 244762 checklists2 pm: 0.4% of 235420 checklists3 pm: 0.3% of 232365 checklists4 pm: 0.3% of 208688 checklists5 pm: 0.4% 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
January0.1%0.1%0.1%0.1%
February0.1%0.1%0.1%0.1%
March0.1%0.1%0.2%0.7%
April1.5%2.2%2.5%2.5%
May2.6%2.1%2.3%2.4%
June2.4%2.2%2.2%2.2%
July2.2%1.8%1.5%1.4%
August1.5%1.3%1.2%1.5%
September1.3%0.7%0.1%0.1%
October0.1%0.1%0.1%0.1%
November0.1%0.1%0.1%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

  • Nevada: arrives early April, in the same week than California
  • Arizona: arrives the second week of March, 3 weeks earlier than California
  • New Mexico: arrives the second week of April, 1 week later than California
  • South Dakota: arrives mid May, 6 weeks later than California

Common questions

When do Bell's Vireos arrive in California?
Bell's Vireos arrive in California in early April, peak in late April (2.5% of checklists), and most are gone by early September.
When do Bell's Vireos leave California?
Most Bell's Vireos have left California by early September, when reports fall below half their usual rate.
When is the best time to see a Bell's Vireo in California?
The Bell's Vireo is reported most often in late April, on about 2.5% of California checklists.
Where in California are Bell's Vireos seen most often?
By county, San Bernardino County, Orange County, and Riverside County have the highest peak reporting rates for the Bell's Vireo (counties with at least 200 checklists).