WhenToBird

Aythya marila · Anatidae

When Do Greater Scaups Arrive in California?

Adult Greater Scaup
Photo: Se Lena, CC BY 4.0 via iNaturalist

Greater Scaups are winter birds in California: the first arrive in late October, they are common by early November, peak in mid January (3.5% of checklists), and most are gone by mid April.

When to look

First arrivalsOct 22-31late October
Common byNov 1-7early November
PeakJan 15-21mid January
Most gone byApr 15-21mid April

Best: mid January. First arrivals late October; most are gone by mid April. Peak: on about 3.5% of California checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  7. Julrare
  8. Augrare
  9. Seprare
  10. Octuncommon
  11. Novcommon
  12. Decpeak season

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

0%1%2%3%4%Jan 1-7: 3.3% of 112336 checklistsJan 8-14: 3.5% of 85518 checklistsJan 15-21: 3.6% of 86488 checklistsJan 22-31: 3.4% of 116174 checklistsFeb 1-7: 3.2% of 75171 checklistsFeb 8-14: 3.1% of 84467 checklistsFeb 15-21: 2.5% of 105683 checklistsFeb 22-28: 2.8% of 83396 checklistsMar 1-7: 2.9% of 77470 checklistsMar 8-14: 2.8% of 75180 checklistsMar 15-21: 2.5% of 80770 checklistsMar 22-31: 2.3% of 114116 checklistsApr 1-7: 2.0% of 84057 checklistsApr 8-14: 1.7% of 83692 checklistsApr 15-21: 1.6% of 89242 checklistsApr 22-30: 1.1% of 114289 checklistsMay 1-7: 0.7% of 85728 checklistsMay 8-14: 0.6% of 91984 checklistsMay 15-21: 0.4% of 75478 checklistsMay 22-31: 0.3% of 106250 checklistsJun 1-7: 0.2% of 70051 checklistsJun 8-14: 0.2% of 67485 checklistsJun 15-21: 0.2% of 66269 checklistsJun 22-30: 0.2% of 79172 checklistsJul 1-7: 0.3% of 62877 checklistsJul 8-14: 0.2% of 60328 checklistsJul 15-21: 0.3% of 59705 checklistsJul 22-31: 0.3% of 83796 checklistsAug 1-7: 0.2% of 60215 checklistsAug 8-14: 0.3% of 60172 checklistsAug 15-21: 0.3% of 59877 checklistsAug 22-31: 0.2% of 89107 checklistsSep 1-7: 0.2% of 72000 checklistsSep 8-14: 0.2% of 71228 checklistsSep 15-21: 0.2% of 76808 checklistsSep 22-30: 0.3% of 100204 checklistsOct 1-7: 0.4% of 76571 checklistsOct 8-14: 0.6% of 80874 checklistsOct 15-21: 0.9% of 74581 checklistsOct 22-31: 1.2% of 97498 checklistsNov 1-7: 1.5% of 70851 checklistsNov 8-14: 1.8% of 72431 checklistsNov 15-21: 1.9% of 66767 checklistsNov 22-30: 2.2% of 94737 checklistsDec 1-7: 2.5% of 65393 checklistsDec 8-14: 2.6% of 67449 checklistsDec 15-21: 2.5% of 83421 checklistsDec 22-31: 2.7% 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. Alameda CountyBest the second week of January · 3791 checklists that week, 161,052 in all19%
  2. Humboldt CountyBest the second week of January · 1919 checklists that week, 95,963 in all13%
  3. San Mateo CountyBest late January · 4843 checklists that week, 148,781 in all12%
  4. Marin CountyBest early February · 2334 checklists that week, 135,728 in all11%
  5. Contra Costa CountyBest late January · 3382 checklists that week, 115,071 in all11%
  6. San Francisco CountyBest early March · 2379 checklists that week, 130,018 in all10%

Best spots

Share of checklists at the peak
  1. Candlestick Point State Recreation AreaSan Francisco County, best late January · 27 checklists that week, 917 in all100%
  2. Redwood Shores Lagoon (Belmont)San Mateo County, best mid February · 26 checklists that week, 359 in all89%
  3. Lakeside ParkAlameda County, best mid February · 23 checklists that week, 453 in all86%
  4. Faro PointAlameda County, best early February · 21 checklists that week, 1,007 in all82%
  5. New MarshAlameda County, best the second week of February · 31 checklists that week, 1,483 in all82%
  6. Mariner ParkSan Mateo County, best the second week of February · 21 checklists that week, 250 in all80%

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

Best time of day

In California, the Greater Scaup is most often listed on checklists started between 12 and 2 pm (2.0% 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: 0.5% of 186053 checklists7 am: 1.3% of 444086 checklists8 am: 1.5% of 535846 checklists9 am: 1.6% of 486061 checklists10 am: 1.7% of 411130 checklists11 am: 1.8% of 325798 checklists12 pm: 1.9% of 269132 checklists1 pm: 2.1% of 244762 checklists2 pm: 1.9% of 235420 checklists3 pm: 1.9% of 232365 checklists4 pm: 1.5% of 208688 checklists5 pm: 1.0% 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
January3.3%3.5%3.6%3.4%
February3.2%3.1%2.5%2.8%
March2.9%2.8%2.5%2.3%
April2.0%1.7%1.6%1.1%
May0.7%0.6%0.4%0.3%
June0.2%0.2%0.2%0.2%
July0.3%0.2%0.3%0.3%
August0.2%0.3%0.3%0.2%
September0.2%0.2%0.2%0.3%
October0.4%0.6%0.9%1.2%
November1.5%1.8%1.9%2.2%
December2.5%2.6%2.5%2.7%

Neighboring states

  • Nevada: arrives early November, 1 week later than California
  • Oregon: arrives the second week of October, 2 weeks earlier than California
  • Washington: arrives late September, 4 weeks earlier than California
  • Colorado: arrives the second week of November, 2 weeks later than California

Common questions

When do Greater Scaups arrive in California?
Greater Scaups are winter birds in California: the first arrive in late October, they are common by early November, peak in mid January (3.5% of checklists), and most are gone by mid April.
When do Greater Scaups leave California?
Most Greater Scaups have left California by mid April, when reports fall below half their usual rate. Stragglers are still reported until late April.
When is the best time to see a Greater Scaup in California?
The Greater Scaup is reported most often in mid January, on about 3.5% of California checklists.
Where in California are Greater Scaups seen most often?
By county, Alameda County, Humboldt County, and San Mateo County have the highest peak reporting rates for the Greater Scaup (counties with at least 200 checklists).