WhenToBird

Thalasseus maximus · Laridae

When Do Royal Terns Arrive in California?

Adult Royal Tern
Photo: Ricard Busquets Reverte, CC BY 4.0 via iNaturalist

Royal Terns arrive in California in the second week of June, peak in the second week of August (2.0% of checklists), and most are gone by the second week of May.

When to look

First arrivalsJun 8-14the second week of June
Common byJun 8-14the second week of June
PeakAug 8-14the second week of August
Most gone byMay 8-14the second week of May

Best: the second week of August. First arrivals the second week of June; most are gone by the second week of May. Peak: on about 2.0% of California checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novpeak season
  12. Decpeak season

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

0%1%2%3%Jan 1-7: 1.7% of 112336 checklistsJan 8-14: 1.7% of 85518 checklistsJan 15-21: 1.8% of 86488 checklistsJan 22-31: 1.6% of 116174 checklistsFeb 1-7: 1.4% of 75171 checklistsFeb 8-14: 1.4% of 84467 checklistsFeb 15-21: 1.4% of 105683 checklistsFeb 22-28: 2.2% of 83396 checklistsMar 1-7: 1.7% of 77470 checklistsMar 8-14: 1.4% of 75180 checklistsMar 15-21: 1.4% of 80770 checklistsMar 22-31: 1.1% of 114116 checklistsApr 1-7: 1.1% of 84057 checklistsApr 8-14: 1.1% of 83692 checklistsApr 15-21: 0.9% of 89242 checklistsApr 22-30: 1.1% of 114289 checklistsMay 1-7: 1.0% of 85728 checklistsMay 8-14: 0.8% of 91984 checklistsMay 15-21: 0.7% of 75478 checklistsMay 22-31: 0.6% of 106250 checklistsJun 1-7: 0.7% of 70051 checklistsJun 8-14: 0.9% of 67485 checklistsJun 15-21: 0.9% of 66269 checklistsJun 22-30: 1.1% of 79172 checklistsJul 1-7: 1.2% of 62877 checklistsJul 8-14: 1.6% of 60328 checklistsJul 15-21: 1.6% of 59705 checklistsJul 22-31: 2.0% of 83796 checklistsAug 1-7: 1.9% of 60215 checklistsAug 8-14: 2.1% of 60172 checklistsAug 15-21: 2.0% of 59877 checklistsAug 22-31: 1.9% of 89107 checklistsSep 1-7: 1.7% of 72000 checklistsSep 8-14: 1.8% of 71228 checklistsSep 15-21: 1.3% of 76808 checklistsSep 22-30: 1.3% of 100204 checklistsOct 1-7: 1.2% of 76571 checklistsOct 8-14: 1.4% of 80874 checklistsOct 15-21: 1.4% of 74581 checklistsOct 22-31: 1.5% of 97498 checklistsNov 1-7: 1.6% of 70851 checklistsNov 8-14: 1.9% of 72431 checklistsNov 15-21: 1.9% of 66767 checklistsNov 22-30: 1.9% of 94737 checklistsDec 1-7: 1.8% of 65393 checklistsDec 8-14: 1.8% of 67449 checklistsDec 15-21: 1.5% of 83421 checklistsDec 22-31: 2.0% 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. San Diego CountyBest late July · 7685 checklists that week, 405,465 in all11%
  2. Orange CountyBest early August · 3735 checklists that week, 244,559 in all7.2%
  3. Santa Barbara CountyBest the second week of January · 2585 checklists that week, 120,616 in all6.8%
  4. San Luis Obispo CountyBest mid November · 2370 checklists that week, 124,667 in all6.8%
  5. Ventura CountyBest early September · 1780 checklists that week, 94,391 in all3.8%
  6. Los Angeles CountyBest mid August · 6078 checklists that week, 410,235 in all3.7%

Best spots

Share of checklists at the peak
  1. San Diego Bay National Wildlife RefugeSan Diego County, best early March · 41 checklists that week, 1,550 in all96%
  2. Ellen Browning Scripps Neighborhood ParkSan Diego County, best early November · 85 checklists that week, 4,587 in all82%
  3. Carpinteria State BeachSanta Barbara County, best the second week of December · 22 checklists that week, 857 in all77%
  4. Torrance County BeachLos Angeles County, best late December · 23 checklists that week, 217 in all76%
  5. Morro Strand State BeachSan Luis Obispo County, best the second week of December · 27 checklists that week, 2,064 in all76%

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

Best time of day

In California, the Royal Tern is most often listed on checklists started between 6 and 8 am (1.9% 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: 2.1% of 186053 checklists7 am: 1.7% of 444086 checklists8 am: 1.5% of 535846 checklists9 am: 1.5% of 486061 checklists10 am: 1.4% of 411130 checklists11 am: 1.4% of 325798 checklists12 pm: 1.5% of 269132 checklists1 pm: 1.5% of 244762 checklists2 pm: 1.6% of 235420 checklists3 pm: 1.4% of 232365 checklists4 pm: 1.1% of 208688 checklists5 pm: 0.9% of 146104 checklists6 pm: 0.7% 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
January1.7%1.7%1.8%1.6%
February1.4%1.4%1.4%2.2%
March1.7%1.4%1.4%1.1%
April1.1%1.1%0.9%1.1%
May1.0%0.8%0.7%0.6%
June0.7%0.9%0.9%1.1%
July1.2%1.6%1.6%2.0%
August1.9%2.1%2.0%1.9%
September1.7%1.8%1.3%1.3%
October1.2%1.4%1.4%1.5%
November1.6%1.9%1.9%1.9%
December1.8%1.8%1.5%2.0%

Neighboring states

  • Texas: arrives late March, 10 weeks earlier than California
  • Louisiana: arrives early April, 9 weeks earlier than California
  • Mississippi: year-round, peaks early September
  • Alabama: arrives mid August, 9 weeks later than California

Common questions

When do Royal Terns arrive in California?
Royal Terns arrive in California in the second week of June, peak in the second week of August (2.0% of checklists), and most are gone by the second week of May.
When do Royal Terns leave California?
Most Royal Terns have left California by the second week of May, when reports fall below half their usual rate.
When is the best time to see a Royal Tern in California?
The Royal Tern is reported most often in the second week of August, on about 2.0% of California checklists.
Where in California are Royal Terns seen most often?
By county, San Diego County, Orange County, and Santa Barbara County have the highest peak reporting rates for the Royal Tern (counties with at least 200 checklists).