WhenToBird

Aythya affinis · Anatidae

When Do Lesser Scaups Arrive in Iowa?

Adult male Lesser Scaup
Photo: Paul Lewis, CC BY 4.0 via iNaturalist

Lesser Scaups are winter birds in Iowa: the first arrive in mid October, they are common by late October, peak in late March (21% of checklists), and most are gone by early May.

When to look

First arrivalsOct 15-21mid October
Common byOct 22-31late October
PeakMar 22-31late March
Most gone byMay 1-7early May

Best: late March. First arrivals mid October; most are gone by early May. Peak: on about 21% of Iowa checklists.

  1. Januncommon
  2. Febcommon
  3. Marpeak season
  4. Aprpeak season
  5. Mayuncommon
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novuncommon
  12. Decuncommon

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

0%10%20%30%Jan 1-7: 3.3% of 5551 checklistsJan 8-14: 2.3% of 3498 checklistsJan 15-21: 1.8% of 3803 checklistsJan 22-31: 1.6% of 4807 checklistsFeb 1-7: 3.1% of 3613 checklistsFeb 8-14: 2.7% of 4173 checklistsFeb 15-21: 3.7% of 5796 checklistsFeb 22-28: 10% of 4394 checklistsMar 1-7: 16% of 5295 checklistsMar 8-14: 18% of 5679 checklistsMar 15-21: 22% of 5418 checklistsMar 22-31: 22% of 8613 checklistsApr 1-7: 20% of 6970 checklistsApr 8-14: 17% of 7511 checklistsApr 15-21: 15% of 8321 checklistsApr 22-30: 8.1% of 11976 checklistsMay 1-7: 3.5% of 11725 checklistsMay 8-14: 1.5% of 12626 checklistsMay 15-21: 0.8% of 9372 checklistsMay 22-31: 0.7% of 10330 checklistsJun 1-7: 0.2% of 5472 checklistsJun 8-14: 0.3% of 4568 checklistsJun 15-21: 0.1% of 3870 checklistsJun 22-30: 0.2% of 4780 checklistsJul 1-7: 0.1% of 4201 checklistsJul 8-14: 0.1% of 3605 checklistsJul 15-21: 0.1% of 3621 checklistsJul 22-31: 0.1% of 5093 checklistsAug 1-7: 0% of 3931 checklistsAug 8-14: 0.1% of 3488 checklistsAug 15-21: 0.1% of 3802 checklistsAug 22-31: 0.1% of 6293 checklistsSep 1-7: 0.1% of 5328 checklistsSep 8-14: 0.1% of 4622 checklistsSep 15-21: 0.1% of 4367 checklistsSep 22-30: 0.1% of 6086 checklistsOct 1-7: 0.2% of 4708 checklistsOct 8-14: 0.6% of 4791 checklistsOct 15-21: 1.5% of 4429 checklistsOct 22-31: 5.6% of 5633 checklistsNov 1-7: 7.8% of 4090 checklistsNov 8-14: 9.3% of 3416 checklistsNov 15-21: 8.4% of 3398 checklistsNov 22-30: 7.2% of 4679 checklistsDec 1-7: 8.2% of 3442 checklistsDec 8-14: 6.8% of 3322 checklistsDec 15-21: 4.7% of 4619 checklistsDec 22-31: 3.8% of 5113 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 Iowa 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 Iowa

Best counties

Share of checklists at the peak
  1. Hancock CountyBest mid March · 11 checklists that week, 449 in all64%
  2. Clay CountyBest the second week of April · 11 checklists that week, 844 in all55%
  3. Palo Alto CountyBest early April · 11 checklists that week, 460 in all52%
  4. Buena Vista CountyBest early April · 57 checklists that week, 2,846 in all51%
  5. Grundy CountyBest late March · 26 checklists that week, 647 in all51%
  6. Hamilton CountyBest mid March · 29 checklists that week, 965 in all51%

Best spots

Share of checklists at the peak
  1. Goose Lake PondJohnson County, best late March · 43 checklists that week, 404 in all89%
  2. Prairie Lakes ParkBlack Hawk County, best the second week of April · 26 checklists that week, 986 in all83%
  3. Hendrickson Marsh Wildlife Management AreaStory County, best early April · 21 checklists that week, 556 in all83%
  4. Lake Manawa State ParkPottawattamie County, best late March · 30 checklists that week, 599 in all81%
  5. Saylorville Recreation Area (Rock Creek)Polk County, best late March · 33 checklists that week, 1,401 in all76%
  6. John Deere MarshDubuque County, best early April · 51 checklists that week, 1,952 in all76%

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

Best time of day

In Iowa, the Lesser Scaup is most often listed on checklists started between 12 and 2 pm (6.6% of those checklists).

0%2%4%6%8%12 am: too few checklists (96) to judge1 am: too few checklists (99) to judge2 am: too few checklists (67) to judge3 am: too few checklists (82) to judge4 am: too few checklists (201) to judge5 am: too few checklists (1888) to judge6 am: 3.2% of 11313 checklists7 am: 4.3% of 25717 checklists8 am: 4.9% of 29755 checklists9 am: 5.7% of 28897 checklists10 am: 6.0% of 26343 checklists11 am: 6.0% of 21210 checklists12 pm: 6.6% of 17662 checklists1 pm: 6.5% of 16595 checklists2 pm: 6.4% of 16405 checklists3 pm: 6.2% of 17030 checklists4 pm: 6.1% of 17378 checklists5 pm: 6.3% of 14251 checklists6 pm: 4.8% of 10349 checklists7 pm: 3.1% of 6233 checklists8 pm: too few checklists (2002) to judge9 pm: too few checklists (392) to judge10 pm: too few checklists (186) to judge11 pm: too few checklists (87) 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%2.3%1.8%1.6%
February3.1%2.7%3.7%10%
March16%18%22%22%
April20%17%15%8.1%
May3.5%1.5%0.8%0.7%
June0.2%0.3%0.1%0.2%
July0.1%0.1%0.1%0.1%
August0%0.1%0.1%0.1%
September0.1%0.1%0.1%0.1%
October0.2%0.6%1.5%5.6%
November7.8%9.3%8.4%7.2%
December8.2%6.8%4.7%3.8%

Neighboring states

  • Missouri: arrives mid October, in the same week than Iowa
  • Wisconsin: arrives the second week of October, 1 week earlier than Iowa
  • Minnesota: arrives late February, 17 weeks later than Iowa
  • Illinois: arrives mid October, in the same week than Iowa

Common questions

When do Lesser Scaups arrive in Iowa?
Lesser Scaups are winter birds in Iowa: the first arrive in mid October, they are common by late October, peak in late March (21% of checklists), and most are gone by early May.
When do Lesser Scaups leave Iowa?
Most Lesser Scaups have left Iowa by early May, when reports fall below half their usual rate. Stragglers are still reported until mid May.
When is the best time to see a Lesser Scaup in Iowa?
The Lesser Scaup is reported most often in late March, on about 21% of Iowa checklists.
Where in Iowa are Lesser Scaups seen most often?
By county, Hancock County, Clay County, and Palo Alto County have the highest peak reporting rates for the Lesser Scaup (counties with at least 200 checklists).