WhenToBird

Common Loon · Gavia immer

When Do Loons Arrive in Illinois?

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

Common Loons are winter birds in Illinois: they arrive in the second week of March, peak in late March (5.6% of checklists), and most are gone by late April. They are the only regular loons in Illinois.

When to look

First arrivalsMar 8-14the second week of March
Common byMar 8-14the second week of March
PeakMar 22-31late March
Most gone byApr 22-30late April

Best: late March. First arrivals the second week of March; most are gone by late April. Peak: on about 5.6% of Illinois checklists.

  1. Janrare
  2. Febnot usually seen
  3. Marpeak season
  4. Aprpeak season
  5. Mayrare
  6. Junnot usually seen
  7. Julnot usually seen
  8. Augnot usually seen
  9. Sepnot usually seen
  10. Octuncommon
  11. Novcommon
  12. Decuncommon

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

Loons in Illinois, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
Common LoonMar 8-14Mar 8-14Mar 22-31Apr 22-305.6%
0%2%4%6%8%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 Illinois 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 Illinois

Best counties for Common Loon

Share of checklists at the peak
  1. Richland CountyBest mid November · 11 checklists that week, 580 in all55%
  2. Moultrie CountyBest the second week of November · 15 checklists that week, 1,367 in all39%
  3. Franklin CountyBest late November · 50 checklists that week, 1,745 in all33%
  4. Shelby CountyBest the second week of November · 17 checklists that week, 1,001 in all32%
  5. Clinton CountyBest mid November · 157 checklists that week, 8,606 in all21%
  6. Lake CountyBest early April · 2788 checklists that week, 113,940 in all19%

Common questions

When do loons arrive in Illinois?
Common Loons are winter birds in Illinois: they arrive in the second week of March, peak in late March (5.6% of checklists), and most are gone by late April. They are the only regular loons in Illinois.
When do loons leave Illinois?
Most Common Loons have left Illinois by late April, when reports fall below half their usual rate.
When is the best time to see loons in Illinois?
The Common Loon is reported most often in late March, on about 5.6% of Illinois checklists.