WhenToBird

Mareca strepera · Anatidae

When Do Gadwalls Arrive in Wisconsin?

Adult Gadwall
Photo: Anne Parsons, CC0 1.0 via iNaturalist

Gadwalls are winter birds in Wisconsin: the first arrive in late September, they are common by early October, peak in late March (9.0% of checklists), and most are gone by the second week of May.

When to look

First arrivalsSep 22-30late September
Common byOct 1-7early October
PeakMar 22-31late March
Most gone byMay 8-14the second week of May

Best: late March. First arrivals late September; most are gone by the second week of May. Peak: on about 9.0% of Wisconsin checklists.

  1. Januncommon
  2. Febuncommon
  3. Marpeak season
  4. Aprpeak season
  5. Maycommon
  6. Junrare
  7. Julrare
  8. Augrare
  9. Sepuncommon
  10. Octcommon
  11. Novcommon
  12. Decuncommon

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

0%5%10%Jan 1-7: 2.4% of 27925 checklistsJan 8-14: 1.7% of 18337 checklistsJan 15-21: 1.4% of 17370 checklistsJan 22-31: 1.4% of 23777 checklistsFeb 1-7: 1.5% of 16656 checklistsFeb 8-14: 1.5% of 18286 checklistsFeb 15-21: 1.8% of 24739 checklistsFeb 22-28: 3.1% of 20113 checklistsMar 1-7: 5.7% of 24024 checklistsMar 8-14: 7.8% of 26722 checklistsMar 15-21: 9.4% of 27238 checklistsMar 22-31: 9.2% of 40171 checklistsApr 1-7: 8.6% of 34961 checklistsApr 8-14: 8.1% of 39128 checklistsApr 15-21: 7.7% of 38887 checklistsApr 22-30: 6.2% of 57231 checklistsMay 1-7: 3.5% of 55115 checklistsMay 8-14: 1.9% of 63098 checklistsMay 15-21: 1.7% of 49821 checklistsMay 22-31: 1.2% of 56796 checklistsJun 1-7: 1.2% of 33621 checklistsJun 8-14: 0.8% of 31282 checklistsJun 15-21: 0.6% of 30186 checklistsJun 22-30: 0.4% of 35128 checklistsJul 1-7: 0.4% of 27088 checklistsJul 8-14: 0.3% of 23293 checklistsJul 15-21: 0.2% of 20933 checklistsJul 22-31: 0.4% of 27595 checklistsAug 1-7: 0.3% of 19147 checklistsAug 8-14: 0.4% of 18286 checklistsAug 15-21: 0.5% of 19195 checklistsAug 22-31: 0.4% of 28229 checklistsSep 1-7: 0.5% of 22408 checklistsSep 8-14: 0.5% of 20857 checklistsSep 15-21: 0.9% of 20707 checklistsSep 22-30: 1.3% of 26469 checklistsOct 1-7: 2.2% of 21069 checklistsOct 8-14: 3.4% of 21011 checklistsOct 15-21: 4.8% of 20006 checklistsOct 22-31: 5.0% of 26362 checklistsNov 1-7: 5.0% of 18928 checklistsNov 8-14: 4.3% of 17052 checklistsNov 15-21: 4.3% of 16291 checklistsNov 22-30: 3.4% of 20564 checklistsDec 1-7: 3.3% of 15354 checklistsDec 8-14: 2.5% of 16294 checklistsDec 15-21: 1.8% of 21430 checklistsDec 22-31: 1.6% of 26314 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 Wisconsin 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 Wisconsin

Best counties

Share of checklists at the peak
  1. Buffalo CountyBest the second week of November · 38 checklists that week, 3,020 in all43%
  2. Trempealeau CountyBest late October · 104 checklists that week, 6,201 in all33%
  3. Columbia CountyBest late March · 937 checklists that week, 15,761 in all28%
  4. Dodge CountyBest mid April · 1131 checklists that week, 34,980 in all27%
  5. Lafayette CountyBest the second week of March · 36 checklists that week, 1,911 in all20%
  6. Vernon CountyBest the second week of November · 123 checklists that week, 13,255 in all18%

Best spots

Share of checklists at the peak
  1. Turvilles BayDane County, best late November · 36 checklists that week, 204 in all99%
  2. Lower Mud Lake Fishery AreaDane County, best the second week of March · 31 checklists that week, 250 in all91%
  3. Riecks LakeBuffalo County, best early November · 20 checklists that week, 140 in all88%
  4. Lottes Park & Boat LaunchDane County, best late January · 22 checklists that week, 207 in all87%
  5. Whalen BayColumbia County, best mid March · 22 checklists that week, 267 in all83%

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

Best time of day

In Wisconsin, the Gadwall is most often listed on checklists started between 1 and 3 pm (4.1% of those checklists).

0%2%4%6%12 am: too few checklists (993) to judge1 am: too few checklists (844) to judge2 am: too few checklists (839) to judge3 am: too few checklists (1488) to judge4 am: too few checklists (5344) to judge5 am: 1.4% of 27016 checklists6 am: 2.1% of 83973 checklists7 am: 2.2% of 160717 checklists8 am: 2.6% of 160531 checklists9 am: 3.1% of 136968 checklists10 am: 3.6% of 119110 checklists11 am: 3.7% of 99116 checklists12 pm: 3.7% of 85078 checklists1 pm: 4.0% of 80688 checklists2 pm: 4.1% of 79140 checklists3 pm: 3.9% of 78599 checklists4 pm: 3.9% of 69767 checklists5 pm: 3.6% of 53229 checklists6 pm: 2.7% of 38769 checklists7 pm: too few checklists (24396) to judge8 pm: too few checklists (10155) to judge9 pm: too few checklists (4990) to judge10 pm: too few checklists (2463) to judge11 pm: too few checklists (1281) 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
January2.4%1.7%1.4%1.4%
February1.5%1.5%1.8%3.1%
March5.7%7.8%9.4%9.2%
April8.6%8.1%7.7%6.2%
May3.5%1.9%1.7%1.2%
June1.2%0.8%0.6%0.4%
July0.4%0.3%0.2%0.4%
August0.3%0.4%0.5%0.4%
September0.5%0.5%0.9%1.3%
October2.2%3.4%4.8%5.0%
November5.0%4.3%4.3%3.4%
December3.3%2.5%1.8%1.6%

Neighboring states

  • Illinois: arrives late September, in the same week than Wisconsin
  • Iowa: arrives the second week of February, 18 weeks later than Wisconsin
  • Michigan: arrives late September, in the same week than Wisconsin
  • Minnesota: arrives mid February, 19 weeks later than Wisconsin

Common questions

When do Gadwalls arrive in Wisconsin?
Gadwalls are winter birds in Wisconsin: the first arrive in late September, they are common by early October, peak in late March (9.0% of checklists), and most are gone by the second week of May.
When do Gadwalls leave Wisconsin?
Most Gadwalls have left Wisconsin by the second week of May, when reports fall below half their usual rate. Stragglers are still reported until early June.
When is the best time to see a Gadwall in Wisconsin?
The Gadwall is reported most often in late March, on about 9.0% of Wisconsin checklists.
Where in Wisconsin are Gadwalls seen most often?
By county, Buffalo County, Trempealeau County, and Columbia County have the highest peak reporting rates for the Gadwall (counties with at least 200 checklists).