WhenToBird

Larus heermanni · Laridae

When Do Heermann's Gulls Arrive in California?

Adult Heermann's Gull
Photo: Ken Clark, CC BY 4.0 via iNaturalist

Heermann's Gulls reach California in late May, are common by mid June, peak in the second week of August (7.4% of checklists), and most are gone by late January.

When to look

First arrivalsMay 22-31late May
Common byJun 15-21mid June
PeakAug 8-14the second week of August
Most gone byJan 22-31late January

Best: the second week of August. First arrivals late May; most are gone by late January. Peak: on about 7.4% of California checklists.

  1. Jancommon
  2. Febuncommon
  3. Maruncommon
  4. Aprrare
  5. Mayrare
  6. Juncommon
  7. Julpeak season
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novpeak season
  12. Deccommon

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

0%2%4%6%8%Jan 1-7: 3.8% of 112336 checklistsJan 8-14: 3.6% of 85518 checklistsJan 15-21: 3.3% of 86488 checklistsJan 22-31: 2.8% of 116174 checklistsFeb 1-7: 2.3% of 75171 checklistsFeb 8-14: 1.8% of 84467 checklistsFeb 15-21: 1.7% of 105683 checklistsFeb 22-28: 2.0% of 83396 checklistsMar 1-7: 1.6% of 77470 checklistsMar 8-14: 1.3% of 75180 checklistsMar 15-21: 1.1% of 80770 checklistsMar 22-31: 0.9% of 114116 checklistsApr 1-7: 0.8% of 84057 checklistsApr 8-14: 0.7% of 83692 checklistsApr 15-21: 0.6% of 89242 checklistsApr 22-30: 0.7% of 114289 checklistsMay 1-7: 0.9% of 85728 checklistsMay 8-14: 0.7% of 91984 checklistsMay 15-21: 0.9% of 75478 checklistsMay 22-31: 1.1% of 106250 checklistsJun 1-7: 1.4% of 70051 checklistsJun 8-14: 1.9% of 67485 checklistsJun 15-21: 2.5% of 66269 checklistsJun 22-30: 3.3% of 79172 checklistsJul 1-7: 4.2% of 62877 checklistsJul 8-14: 5.3% of 60328 checklistsJul 15-21: 6.2% of 59705 checklistsJul 22-31: 7.1% of 83796 checklistsAug 1-7: 7.2% of 60215 checklistsAug 8-14: 7.5% of 60172 checklistsAug 15-21: 7.4% of 59877 checklistsAug 22-31: 6.8% of 89107 checklistsSep 1-7: 6.4% of 72000 checklistsSep 8-14: 6.1% of 71228 checklistsSep 15-21: 5.4% of 76808 checklistsSep 22-30: 5.1% of 100204 checklistsOct 1-7: 4.6% of 76571 checklistsOct 8-14: 4.4% of 80874 checklistsOct 15-21: 4.5% of 74581 checklistsOct 22-31: 4.5% of 97498 checklistsNov 1-7: 5.5% of 70851 checklistsNov 8-14: 5.7% of 72431 checklistsNov 15-21: 5.7% of 66767 checklistsNov 22-30: 5.5% of 94737 checklistsDec 1-7: 4.9% of 65393 checklistsDec 8-14: 4.5% of 67449 checklistsDec 15-21: 3.2% of 83421 checklistsDec 22-31: 4.2% 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. Monterey CountyBest the second week of November · 3190 checklists that week, 132,505 in all40%
  2. San Luis Obispo CountyBest the second week of August · 2076 checklists that week, 124,667 in all24%
  3. San Mateo CountyBest the second week of August · 2354 checklists that week, 148,781 in all20%
  4. Santa Cruz CountyBest early August · 2185 checklists that week, 140,819 in all17%
  5. Ventura CountyBest the second week of August · 1473 checklists that week, 94,391 in all16%
  6. Marin CountyBest the second week of August · 2135 checklists that week, 135,728 in all15%

Best spots

Share of checklists at the peak
  1. White Point County BeachLos Angeles County, best early September · 22 checklists that week, 444 in all100%
  2. Belmont Plaza BeachLos Angeles County, best late July · 20 checklists that week, 602 in all100%
  3. San Gregorio State BeachSan Mateo County, best late August · 25 checklists that week, 568 in all97%
  4. Crespi PondMonterey County, best the second week of November · 784 checklists that week, 7,637 in all97%
  5. Seal RocksSan Francisco County, best mid September · 20 checklists that week, 898 in all96%

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

Best time of day

In California, the Heermann's Gull is most often listed on checklists started between 1 and 3 pm (3.9% 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: 4.1% of 186053 checklists7 am: 3.7% of 444086 checklists8 am: 3.2% of 535846 checklists9 am: 3.3% of 486061 checklists10 am: 3.4% of 411130 checklists11 am: 3.7% of 325798 checklists12 pm: 3.7% of 269132 checklists1 pm: 3.9% of 244762 checklists2 pm: 4.0% of 235420 checklists3 pm: 3.7% of 232365 checklists4 pm: 3.2% of 208688 checklists5 pm: 2.8% of 146104 checklists6 pm: 2.5% 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
January3.8%3.6%3.3%2.8%
February2.3%1.8%1.7%2.0%
March1.6%1.3%1.1%0.9%
April0.8%0.7%0.6%0.7%
May0.9%0.7%0.9%1.1%
June1.4%1.9%2.5%3.3%
July4.2%5.3%6.2%7.1%
August7.2%7.5%7.4%6.8%
September6.4%6.1%5.4%5.1%
October4.6%4.4%4.5%4.5%
November5.5%5.7%5.7%5.5%
December4.9%4.5%3.2%4.2%

Neighboring states

  • Oregon: arrives early July, 5 weeks later than California
  • Washington: arrives early July, 5 weeks later than California

Common questions

When do Heermann's Gulls arrive in California?
Heermann's Gulls reach California in late May, are common by mid June, peak in the second week of August (7.4% of checklists), and most are gone by late January.
When do Heermann's Gulls leave California?
Most Heermann's Gulls have left California by late January, when reports fall below half their usual rate. Stragglers are still reported until mid March.
When is the best time to see a Heermann's Gull in California?
The Heermann's Gull is reported most often in the second week of August, on about 7.4% of California checklists.
Where in California are Heermann's Gulls seen most often?
By county, Monterey County, San Luis Obispo County, and San Mateo County have the highest peak reporting rates for the Heermann's Gull (counties with at least 200 checklists).