WhenToBird

Gavia immer · Gaviidae

When Do Common Loons Arrive in Wisconsin?

Adult Common Loon
Photo: Hungry-Sarracenia Photo, CC BY 4.0 via iNaturalist

Common Loons arrive in Wisconsin in mid March, peak in the second week of April (7.6% of checklists), and most are gone by early December.

When to look

First arrivalsMar 15-21mid March
Common byMar 15-21mid March
PeakApr 8-14the second week of April
Most gone byDec 1-7early December

Best: the second week of April. First arrivals mid March; most are gone by early December. Peak: on about 7.6% of Wisconsin checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marcommon
  4. Aprpeak season
  5. Maycommon
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Sepuncommon
  10. Octpeak season
  11. Novpeak season
  12. Decuncommon

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

0%5%10%Jan 1-7: 0.2% of 27925 checklistsJan 8-14: 0.1% of 18337 checklistsJan 15-21: 0% of 17370 checklistsJan 22-31: 0% of 23777 checklistsFeb 1-7: 0% of 16656 checklistsFeb 8-14: 0% of 18286 checklistsFeb 15-21: 0% of 24739 checklistsFeb 22-28: 0% of 20113 checklistsMar 1-7: 0.1% of 24024 checklistsMar 8-14: 0.1% of 26722 checklistsMar 15-21: 0.9% of 27238 checklistsMar 22-31: 5.2% of 40171 checklistsApr 1-7: 8.1% of 34961 checklistsApr 8-14: 8.0% of 39128 checklistsApr 15-21: 6.8% of 38887 checklistsApr 22-30: 4.9% of 57231 checklistsMay 1-7: 3.3% of 55115 checklistsMay 8-14: 2.3% of 63098 checklistsMay 15-21: 2.3% of 49821 checklistsMay 22-31: 3.1% of 56796 checklistsJun 1-7: 2.7% of 33621 checklistsJun 8-14: 2.9% of 31282 checklistsJun 15-21: 3.3% of 30186 checklistsJun 22-30: 3.5% of 35128 checklistsJul 1-7: 4.7% of 27088 checklistsJul 8-14: 4.6% of 23293 checklistsJul 15-21: 4.3% of 20933 checklistsJul 22-31: 4.3% of 27595 checklistsAug 1-7: 4.7% of 19147 checklistsAug 8-14: 4.1% of 18286 checklistsAug 15-21: 3.9% of 19195 checklistsAug 22-31: 3.3% of 28229 checklistsSep 1-7: 2.6% of 22408 checklistsSep 8-14: 2.1% of 20857 checklistsSep 15-21: 2.1% of 20707 checklistsSep 22-30: 1.7% of 26469 checklistsOct 1-7: 1.9% of 21069 checklistsOct 8-14: 2.0% of 21011 checklistsOct 15-21: 3.7% of 20006 checklistsOct 22-31: 6.6% of 26362 checklistsNov 1-7: 7.3% of 18928 checklistsNov 8-14: 7.1% of 17052 checklistsNov 15-21: 6.2% of 16291 checklistsNov 22-30: 3.7% of 20564 checklistsDec 1-7: 2.0% of 15354 checklistsDec 8-14: 1.0% of 16294 checklistsDec 15-21: 0.4% of 21430 checklistsDec 22-31: 0.2% 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. Vilas CountyBest late August · 464 checklists that week, 16,082 in all45%
  2. Sawyer CountyBest the second week of August · 108 checklists that week, 7,502 in all38%
  3. Oneida CountyBest the second week of August · 285 checklists that week, 14,600 in all37%
  4. Washburn CountyBest early August · 216 checklists that week, 7,099 in all36%
  5. Ashland CountyBest late October · 464 checklists that week, 16,576 in all32%
  6. Forest CountyBest early August · 186 checklists that week, 7,461 in all30%

Best spots

Share of checklists at the peak
  1. Park Lake 56Columbia County, best early April · 36 checklists that week, 123 in all98%
  2. Little Muskego Lake (east)Waukesha County, best the second week of April · 35 checklists that week, 186 in all96%
  3. Statenaker LakeVilas County, best the second week of July · 38 checklists that week, 2,030 in all93%
  4. Monona BayDane County, best the second week of April · 27 checklists that week, 565 in all92%
  5. Little Muskego LakeWaukesha County, best early April · 21 checklists that week, 234 in all91%
  6. Powell Marsh Wildlife AreaVilas County, best early June · 21 checklists that week, 480 in all83%

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

Best time of day

In Wisconsin, the Common Loon is most often listed on checklists started between 5 and 7 am (5.3% of those checklists).

0%2%4%6%8%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: 6.6% of 27016 checklists6 am: 4.9% of 83973 checklists7 am: 3.6% of 160717 checklists8 am: 3.1% of 160531 checklists9 am: 2.9% of 136968 checklists10 am: 2.9% of 119110 checklists11 am: 2.6% of 99116 checklists12 pm: 2.4% of 85078 checklists1 pm: 2.6% of 80688 checklists2 pm: 2.7% of 79140 checklists3 pm: 2.7% of 78599 checklists4 pm: 3.0% of 69767 checklists5 pm: 3.3% of 53229 checklists6 pm: 3.3% 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
January0.2%0.1%0%0%
February0%0%0%0%
March0.1%0.1%0.9%5.2%
April8.1%8.0%6.8%4.9%
May3.3%2.3%2.3%3.1%
June2.7%2.9%3.3%3.5%
July4.7%4.6%4.3%4.3%
August4.7%4.1%3.9%3.3%
September2.6%2.1%2.1%1.7%
October1.9%2.0%3.7%6.6%
November7.3%7.1%6.2%3.7%
December2.0%1.0%0.4%0.2%

Neighboring states

  • Illinois: arrives the second week of March, 1 week earlier than Wisconsin
  • Iowa: arrives the second week of October, 21 weeks earlier than Wisconsin
  • Michigan: arrives mid March, in the same week than Wisconsin
  • Minnesota: arrives late March, 1 week later than Wisconsin

Common questions

When do Common Loons arrive in Wisconsin?
Common Loons arrive in Wisconsin in mid March, peak in the second week of April (7.6% of checklists), and most are gone by early December.
When do Common Loons leave Wisconsin?
Most Common Loons have left Wisconsin by early December, when reports fall below half their usual rate. Stragglers are still reported until the second week of December.
When is the best time to see a Common Loon in Wisconsin?
The Common Loon is reported most often in the second week of April, on about 7.6% of Wisconsin checklists.
Where in Wisconsin are Common Loons seen most often?
By county, Vilas County, Sawyer County, and Oneida County have the highest peak reporting rates for the Common Loon (counties with at least 200 checklists).