WhenToBird

Common Loon · Gavia immer

When Do 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. They are the only regular loons in Wisconsin.

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.

Loons in Wisconsin, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
Common LoonMar 15-21Mar 15-21Apr 8-14Dec 1-77.6%
0%5%10%Common LoonJanFebMarAprMayJunJulAugSepOctNovDec
  • Common Loon
Share of complete checklists reporting each species, by week (4 per month). Gaps: fewer than 10 checklists that week.

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.

Where in Wisconsin

Best counties for Common Loon

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%

Common questions

When do 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. They are the only regular loons in Wisconsin.
When do 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 loons in Wisconsin?
The Common Loon is reported most often in the second week of April, on about 7.6% of Wisconsin checklists.