WhenToBird

Gavia immer · Gaviidae

When Do Common 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.

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.

0%2%4%6%8%Jan 1-7: 0.3% of 29700 checklistsJan 8-14: 0.2% of 20189 checklistsJan 15-21: 0.1% of 19784 checklistsJan 22-31: 0.1% of 26641 checklistsFeb 1-7: 0.1% of 20478 checklistsFeb 8-14: 0.1% of 21967 checklistsFeb 15-21: 0.1% of 28735 checklistsFeb 22-28: 0.1% of 24223 checklistsMar 1-7: 0.2% of 26775 checklistsMar 8-14: 1.0% of 27579 checklistsMar 15-21: 3.0% of 27193 checklistsMar 22-31: 6.9% of 42278 checklistsApr 1-7: 5.9% of 34579 checklistsApr 8-14: 3.4% of 38290 checklistsApr 15-21: 2.4% of 39261 checklistsApr 22-30: 0.9% of 59584 checklistsMay 1-7: 0.5% of 60485 checklistsMay 8-14: 0.3% of 59647 checklistsMay 15-21: 0.2% of 43173 checklistsMay 22-31: 0.1% of 47913 checklistsJun 1-7: 0.1% of 31151 checklistsJun 8-14: 0.1% of 27692 checklistsJun 15-21: 0.1% of 23983 checklistsJun 22-30: 0.1% of 28448 checklistsJul 1-7: 0.1% of 21273 checklistsJul 8-14: 0.1% of 19284 checklistsJul 15-21: 0.1% of 17712 checklistsJul 22-31: 0.1% of 24500 checklistsAug 1-7: 0.1% of 18498 checklistsAug 8-14: 0.1% of 19331 checklistsAug 15-21: 0.1% of 19983 checklistsAug 22-31: 0.1% of 31892 checklistsSep 1-7: 0.1% of 26396 checklistsSep 8-14: 0.1% of 25011 checklistsSep 15-21: 0.1% of 23597 checklistsSep 22-30: 0.1% of 30638 checklistsOct 1-7: 0.1% of 23949 checklistsOct 8-14: 0.1% of 24412 checklistsOct 15-21: 0.4% of 22359 checklistsOct 22-31: 1.7% of 29794 checklistsNov 1-7: 3.2% of 21877 checklistsNov 8-14: 3.4% of 19742 checklistsNov 15-21: 2.8% of 18989 checklistsNov 22-30: 2.3% of 23905 checklistsDec 1-7: 1.2% of 16935 checklistsDec 8-14: 0.7% of 16687 checklistsDec 15-21: 0.4% of 20931 checklistsDec 22-31: 0.3% of 29011 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 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.

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 Illinois

Best counties

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%

Best spots

Share of checklists at the peak
  1. Channel LakeLake County, best early April · 28 checklists that week, 369 in all92%
  2. Diamond Lake Recreation CenterLake County, best early April · 28 checklists that week, 262 in all91%
  3. Axehead LakeCook County, best the second week of April · 72 checklists that week, 937 in all86%
  4. Hastings Lake Forest PreserveLake County, best the second week of April · 33 checklists that week, 1,040 in all85%
  5. Lake MarieLake County, best late March · 50 checklists that week, 127 in all85%
  6. Pulaski Woods (Maple Lake)Cook County, best the second week of April · 31 checklists that week, 819 in all79%

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

Best time of day

In Illinois, the Common Loon is most often listed on checklists started between 1 and 3 pm (1.2% of those checklists).

0%0.5%1%1.5%12 am: too few checklists (484) to judge1 am: too few checklists (631) to judge2 am: too few checklists (485) to judge3 am: too few checklists (610) to judge4 am: too few checklists (2321) to judge5 am: too few checklists (23536) to judge6 am: 1.2% of 95511 checklists7 am: 1.0% of 164584 checklists8 am: 0.9% of 163654 checklists9 am: 0.9% of 141804 checklists10 am: 1.0% of 122882 checklists11 am: 1.1% of 100640 checklists12 pm: 1.1% of 89894 checklists1 pm: 1.1% of 82729 checklists2 pm: 1.2% of 79801 checklists3 pm: 1.1% of 82169 checklists4 pm: 0.9% of 75124 checklists5 pm: 0.9% of 57708 checklists6 pm: 0.8% of 41843 checklists7 pm: too few checklists (20943) to judge8 pm: too few checklists (6131) to judge9 pm: too few checklists (1677) to judge10 pm: too few checklists (843) to judge11 pm: too few checklists (448) 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
January0.3%0.2%0.1%0.1%
February0.1%0.1%0.1%0.1%
March0.2%1.0%3.0%6.9%
April5.9%3.4%2.4%0.9%
May0.5%0.3%0.2%0.1%
June0.1%0.1%0.1%0.1%
July0.1%0.1%0.1%0.1%
August0.1%0.1%0.1%0.1%
September0.1%0.1%0.1%0.1%
October0.1%0.1%0.4%1.7%
November3.2%3.4%2.8%2.3%
December1.2%0.7%0.4%0.3%

Neighboring states

  • Indiana: arrives early March, 1 week earlier than Illinois
  • Wisconsin: arrives mid March, 1 week later than Illinois
  • Michigan: arrives mid March, 1 week later than Illinois
  • Iowa: arrives the second week of October, 20 weeks earlier than Illinois

Common questions

When do Common 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.
When do Common 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 a Common Loon in Illinois?
The Common Loon is reported most often in late March, on about 5.6% of Illinois checklists.
Where in Illinois are Common Loons seen most often?
By county, Richland County, Moultrie County, and Franklin County have the highest peak reporting rates for the Common Loon (counties with at least 200 checklists).