WhenToBird

Aythya marila · Anatidae

When Do Greater Scaups Arrive in Illinois?

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

Greater Scaups are winter birds in Illinois: the first arrive in early November, they are common by mid November, peak in early March (5.1% of checklists), and most are gone by early April.

When to look

First arrivalsNov 1-7early November
Common byNov 15-21mid November
PeakMar 1-7early March
Most gone byApr 1-7early April

Best: early March. First arrivals early November; most are gone by early April. Peak: on about 5.1% of Illinois checklists.

  1. Janpeak season
  2. Febpeak season
  3. Marpeak season
  4. Apruncommon
  5. Maynot usually seen
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novuncommon
  12. Deccommon

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

0%2%4%6%Jan 1-7: 2.8% of 29700 checklistsJan 8-14: 3.4% of 20189 checklistsJan 15-21: 3.5% of 19784 checklistsJan 22-31: 4.0% of 26641 checklistsFeb 1-7: 4.7% of 20478 checklistsFeb 8-14: 4.1% of 21967 checklistsFeb 15-21: 3.9% of 28735 checklistsFeb 22-28: 5.5% of 24223 checklistsMar 1-7: 5.3% of 26775 checklistsMar 8-14: 4.4% of 27579 checklistsMar 15-21: 3.6% of 27193 checklistsMar 22-31: 2.8% of 42278 checklistsApr 1-7: 1.5% of 34579 checklistsApr 8-14: 0.8% of 38290 checklistsApr 15-21: 0.5% of 39261 checklistsApr 22-30: 0.2% of 59584 checklistsMay 1-7: 0.1% of 60485 checklistsMay 8-14: 0.1% of 59647 checklistsMay 15-21: 0.1% of 43173 checklistsMay 22-31: 0.1% of 47913 checklistsJun 1-7: 0.1% of 31151 checklistsJun 8-14: 0.1% of 27692 checklistsJun 15-21: 0.1% of 23983 checklistsJun 22-30: 0.1% of 28448 checklistsJul 1-7: 0.1% of 21273 checklistsJul 8-14: 0.1% of 19284 checklistsJul 15-21: 0.1% of 17712 checklistsJul 22-31: 0.1% of 24500 checklistsAug 1-7: 0.1% of 18498 checklistsAug 8-14: 0.1% of 19331 checklistsAug 15-21: 0.1% of 19983 checklistsAug 22-31: 0.1% of 31892 checklistsSep 1-7: 0% of 26396 checklistsSep 8-14: 0% of 25011 checklistsSep 15-21: 0.1% of 23597 checklistsSep 22-30: 0.1% of 30638 checklistsOct 1-7: 0.3% of 23949 checklistsOct 8-14: 0.2% of 24412 checklistsOct 15-21: 0.5% of 22359 checklistsOct 22-31: 0.8% of 29794 checklistsNov 1-7: 1.3% of 21877 checklistsNov 8-14: 1.6% of 19742 checklistsNov 15-21: 1.9% of 18989 checklistsNov 22-30: 1.9% of 23905 checklistsDec 1-7: 2.2% of 16935 checklistsDec 8-14: 2.6% of 16687 checklistsDec 15-21: 2.0% of 20931 checklistsDec 22-31: 2.8% of 29011 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 Illinois 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 Illinois

Best counties

Share of checklists at the peak
  1. Putnam CountyBest late March · 82 checklists that week, 3,333 in all17%
  2. Lake CountyBest the second week of February · 1942 checklists that week, 113,940 in all15%
  3. Cook CountyBest early March · 7667 checklists that week, 432,644 in all11%
  4. Calhoun CountyBest late November · 10 checklists that week, 786 in all11%
  5. Clark CountyBest the second week of February · 39 checklists that week, 2,005 in all10%
  6. Shelby CountyBest mid January · 27 checklists that week, 1,001 in all9.8%

Best spots

Share of checklists at the peak
  1. Jackson (Andrew) (Yacht Harbor)Cook County, best late January · 55 checklists that week, 940 in all80%
  2. Adeline Jay Geo-Karis Illinois Beach State Park (north)Lake County, best the second week of February · 192 checklists that week, 5,119 in all79%
  3. Lincoln (Abraham) (Belmont Harbor)Cook County, best late February · 43 checklists that week, 1,176 in all73%
  4. Chicago HarborCook County, best the second week of February · 32 checklists that week, 885 in all71%
  5. Park No. 566Cook County, best early February · 61 checklists that week, 3,444 in all70%
  6. CalumetCook County, best late February · 54 checklists that week, 1,381 in all70%

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

Best time of day

In Illinois, the Greater Scaup is most often listed on checklists started between 11 am and 1 pm (1.7% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (484) to judge1 am: too few checklists (631) to judge2 am: too few checklists (485) to judge3 am: too few checklists (610) to judge4 am: too few checklists (2321) to judge5 am: too few checklists (23536) to judge6 am: 1.0% of 95511 checklists7 am: 1.5% of 164584 checklists8 am: 1.2% of 163654 checklists9 am: 1.4% of 141804 checklists10 am: 1.6% of 122882 checklists11 am: 1.7% of 100640 checklists12 pm: 1.7% of 89894 checklists1 pm: 1.7% of 82729 checklists2 pm: 1.6% of 79801 checklists3 pm: 1.5% of 82169 checklists4 pm: 0.9% of 75124 checklists5 pm: 0.5% of 57708 checklists6 pm: 0.2% of 41843 checklists7 pm: too few checklists (20943) to judge8 pm: too few checklists (6131) to judge9 pm: too few checklists (1677) to judge10 pm: too few checklists (843) to judge11 pm: too few checklists (448) 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
January2.8%3.4%3.5%4.0%
February4.7%4.1%3.9%5.5%
March5.3%4.4%3.6%2.8%
April1.5%0.8%0.5%0.2%
May0.1%0.1%0.1%0.1%
June0.1%0.1%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0.1%0.1%0.1%0.1%
September0%0%0.1%0.1%
October0.3%0.2%0.5%0.8%
November1.3%1.6%1.9%1.9%
December2.2%2.6%2.0%2.8%

Neighboring states

  • Indiana: arrives late November, 3 weeks later than Illinois
  • Wisconsin: arrives mid October, 2 weeks earlier than Illinois
  • Michigan: arrives the second week of October, 3 weeks earlier than Illinois
  • Iowa: arrives mid November, 2 weeks later than Illinois

Common questions

When do Greater Scaups arrive in Illinois?
Greater Scaups are winter birds in Illinois: the first arrive in early November, they are common by mid November, peak in early March (5.1% of checklists), and most are gone by early April.
When do Greater Scaups leave Illinois?
Most Greater Scaups have left Illinois by early April, when reports fall below half their usual rate.
When is the best time to see a Greater Scaup in Illinois?
The Greater Scaup is reported most often in early March, on about 5.1% of Illinois checklists.
Where in Illinois are Greater Scaups seen most often?
By county, Putnam County, Lake County, and Cook County have the highest peak reporting rates for the Greater Scaup (counties with at least 200 checklists).