WhenToBird

Anas platyrhynchos · Anatidae

When Do Mallards Arrive in Wisconsin?

Adult male Mallard
Photo: euqirneto, CC BY 4.0 via iNaturalist

Mallards are in Wisconsin all year, but most are here in spring: numbers build from early March, peak in the second week of April (48% of checklists), and fall back by mid May. In the quietest week (early July) they are still on about 16% of checklists.

When to look

Numbers buildMar 1-7early March
PeakApr 8-14the second week of April
Fall back byMay 15-21mid May
FewestJul 1-7early July

Best: the second week of April. Here all year; numbers build from early March and fall back by mid May. Peak: on about 48% of Wisconsin checklists.

  1. Jancommon
  2. Febcommon
  3. Marpeak season
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Sepcommon
  10. Octcommon
  11. Novcommon
  12. Deccommon

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

0%20%40%60%Jan 1-7: 24% of 27925 checklistsJan 8-14: 21% of 18337 checklistsJan 15-21: 19% of 17370 checklistsJan 22-31: 19% of 23777 checklistsFeb 1-7: 19% of 16656 checklistsFeb 8-14: 18% of 18286 checklistsFeb 15-21: 18% of 24739 checklistsFeb 22-28: 26% of 20113 checklistsMar 1-7: 34% of 24024 checklistsMar 8-14: 40% of 26722 checklistsMar 15-21: 44% of 27238 checklistsMar 22-31: 47% of 40171 checklistsApr 1-7: 49% of 34961 checklistsApr 8-14: 49% of 39128 checklistsApr 15-21: 48% of 38887 checklistsApr 22-30: 47% of 57231 checklistsMay 1-7: 43% of 55115 checklistsMay 8-14: 38% of 63098 checklistsMay 15-21: 37% of 49821 checklistsMay 22-31: 32% of 56796 checklistsJun 1-7: 25% of 33621 checklistsJun 8-14: 20% of 31282 checklistsJun 15-21: 17% of 30186 checklistsJun 22-30: 15% of 35128 checklistsJul 1-7: 16% of 27088 checklistsJul 8-14: 16% of 23293 checklistsJul 15-21: 18% of 20933 checklistsJul 22-31: 21% of 27595 checklistsAug 1-7: 22% of 19147 checklistsAug 8-14: 24% of 18286 checklistsAug 15-21: 25% of 19195 checklistsAug 22-31: 25% of 28229 checklistsSep 1-7: 24% of 22408 checklistsSep 8-14: 24% of 20857 checklistsSep 15-21: 24% of 20707 checklistsSep 22-30: 25% of 26469 checklistsOct 1-7: 26% of 21069 checklistsOct 8-14: 27% of 21011 checklistsOct 15-21: 30% of 20006 checklistsOct 22-31: 33% of 26362 checklistsNov 1-7: 35% of 18928 checklistsNov 8-14: 33% of 17052 checklistsNov 15-21: 34% of 16291 checklistsNov 22-30: 31% of 20564 checklistsDec 1-7: 27% of 15354 checklistsDec 8-14: 24% of 16294 checklistsDec 15-21: 22% of 21430 checklistsDec 22-31: 20% 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. Columbia CountyBest early April · 717 checklists that week, 15,761 in all66%
  2. Brown CountyBest early April · 1093 checklists that week, 36,306 in all64%
  3. Dane CountyBest mid April · 7729 checklists that week, 226,084 in all62%
  4. Calumet CountyBest early April · 419 checklists that week, 12,359 in all61%
  5. Winnebago CountyBest late April · 941 checklists that week, 26,460 in all60%
  6. Kewaunee CountyBest mid March · 212 checklists that week, 9,747 in all59%

Best spots

Share of checklists at the peak
  1. Willow RiverSt. Croix County, best early January · 20 checklists that week, 372 in all100%
  2. Doty Bayorgeon Recreaion AreaOutagamie County, best late January · 21 checklists that week, 456 in all100%
  3. Duck Creek (Lancaster Creek)Brown County, best late January · 25 checklists that week, 298 in all100%
  4. Monterey ParkRock County, best late April · 23 checklists that week, 564 in all100%
  5. McFarland Rough Fish StationDane County, best early February · 20 checklists that week, 389 in all100%

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

Best time of day

In Wisconsin, the Mallard is most often listed on checklists started between 5 and 7 pm (36% of those checklists).

0%10%20%30%40%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: 27% of 27016 checklists6 am: 31% of 83973 checklists7 am: 29% of 160717 checklists8 am: 30% of 160531 checklists9 am: 30% of 136968 checklists10 am: 30% of 119110 checklists11 am: 30% of 99116 checklists12 pm: 30% of 85078 checklists1 pm: 32% of 80688 checklists2 pm: 32% of 79140 checklists3 pm: 33% of 78599 checklists4 pm: 34% of 69767 checklists5 pm: 36% of 53229 checklists6 pm: 35% 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
January24%21%19%19%
February19%18%18%26%
March34%40%44%47%
April49%49%48%47%
May43%38%37%32%
June25%20%17%15%
July16%16%18%21%
August22%24%25%25%
September24%24%24%25%
October26%27%30%33%
November35%33%34%31%
December27%24%22%20%

Neighboring states

  • Illinois: year-round, peaks late March
  • Iowa: arrives late February, 1 week earlier than Wisconsin
  • Michigan: year-round, peaks early April
  • Minnesota: arrives the second week of March, 1 week later than Wisconsin

Common questions

When do Mallards arrive in Wisconsin?
Mallards are in Wisconsin all year, but most are here in spring: numbers build from early March, peak in the second week of April (48% of checklists), and fall back by mid May. In the quietest week (early July) they are still on about 16% of checklists.
When do Mallards leave Wisconsin?
Mallards never fully leave Wisconsin: numbers fall back below half their usual rate by mid May, but some are still reported in every week, about 16% of checklists at the low.
When is the best time to see a Mallard in Wisconsin?
The Mallard is reported most often in the second week of April, on about 48% of Wisconsin checklists.
Where in Wisconsin are Mallards seen most often?
By county, Columbia County, Brown County, and Dane County have the highest peak reporting rates for the Mallard (counties with at least 200 checklists).