WhenToBird

Quiscalus quiscula · Icteridae

When Do Common Grackles Arrive in Illinois?

Adult Common Grackle
Photo: Derek Spencer, CC BY 4.0 via iNaturalist

Common Grackles reach Illinois in the second week of February, are common by early March, peak in mid May (44% of checklists), and most are gone by mid October.

When to look

First arrivalsFeb 8-14the second week of February
Common byMar 1-7early March
PeakMay 15-21mid May
Most gone byOct 15-21mid October

Best: mid May. First arrivals the second week of February; most are gone by mid October. Peak: on about 44% of Illinois checklists.

  1. Janrare
  2. Febuncommon
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augcommon
  9. Sepuncommon
  10. Octuncommon
  11. Novuncommon
  12. Decrare

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

0%20%40%60%Jan 1-7: 1.9% of 29700 checklistsJan 8-14: 2.1% of 20189 checklistsJan 15-21: 2.3% of 19784 checklistsJan 22-31: 2.1% of 26641 checklistsFeb 1-7: 2.6% of 20478 checklistsFeb 8-14: 3.2% of 21967 checklistsFeb 15-21: 5.1% of 28735 checklistsFeb 22-28: 9.6% of 24223 checklistsMar 1-7: 21% of 26775 checklistsMar 8-14: 28% of 27579 checklistsMar 15-21: 31% of 27193 checklistsMar 22-31: 33% of 42278 checklistsApr 1-7: 34% of 34579 checklistsApr 8-14: 36% of 38290 checklistsApr 15-21: 35% of 39261 checklistsApr 22-30: 37% of 59584 checklistsMay 1-7: 39% of 60485 checklistsMay 8-14: 42% of 59647 checklistsMay 15-21: 45% of 43173 checklistsMay 22-31: 45% of 47913 checklistsJun 1-7: 38% of 31151 checklistsJun 8-14: 37% of 27692 checklistsJun 15-21: 38% of 23983 checklistsJun 22-30: 35% of 28448 checklistsJul 1-7: 33% of 21273 checklistsJul 8-14: 29% of 19284 checklistsJul 15-21: 25% of 17712 checklistsJul 22-31: 21% of 24500 checklistsAug 1-7: 19% of 18498 checklistsAug 8-14: 16% of 19331 checklistsAug 15-21: 15% of 19983 checklistsAug 22-31: 14% of 31892 checklistsSep 1-7: 13% of 26396 checklistsSep 8-14: 13% of 25011 checklistsSep 15-21: 13% of 23597 checklistsSep 22-30: 13% of 30638 checklistsOct 1-7: 14% of 23949 checklistsOct 8-14: 15% of 24412 checklistsOct 15-21: 14% of 22359 checklistsOct 22-31: 12% of 29794 checklistsNov 1-7: 9.0% of 21877 checklistsNov 8-14: 5.8% of 19742 checklistsNov 15-21: 3.5% of 18989 checklistsNov 22-30: 2.5% of 23905 checklistsDec 1-7: 2.4% of 16935 checklistsDec 8-14: 1.9% of 16687 checklistsDec 15-21: 2.1% of 20931 checklistsDec 22-31: 2.4% 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. Knox CountyBest early April · 163 checklists that week, 6,781 in all77%
  2. Iroquois CountyBest late May · 92 checklists that week, 2,566 in all74%
  3. Bureau CountyBest late May · 321 checklists that week, 10,244 in all74%
  4. Morgan CountyBest early June · 15 checklists that week, 1,463 in all72%
  5. Christian CountyBest mid May · 39 checklists that week, 1,446 in all70%
  6. Crawford CountyBest late May · 30 checklists that week, 804 in all68%

Best spots

Share of checklists at the peak
  1. Iroquois LakeIroquois County, best mid June · 26 checklists that week, 770 in all100%
  2. Lake PetersburgMenard County, best mid June · 29 checklists that week, 1,200 in all97%
  3. Whispering Willows ParkKankakee County, best the second week of June · 21 checklists that week, 1,147 in all97%
  4. Riis (Jacob)Cook County, best late July · 22 checklists that week, 914 in all96%

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

Best time of day

In Illinois, the Common Grackle is most often listed on checklists started between 6 and 8 am (31% of those checklists).

0%10%20%30%40%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: 34% of 95511 checklists7 am: 29% of 164584 checklists8 am: 25% of 163654 checklists9 am: 21% of 141804 checklists10 am: 19% of 122882 checklists11 am: 17% of 100640 checklists12 pm: 17% of 89894 checklists1 pm: 16% of 82729 checklists2 pm: 16% of 79801 checklists3 pm: 17% of 82169 checklists4 pm: 21% of 75124 checklists5 pm: 25% of 57708 checklists6 pm: 26% 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
January1.9%2.1%2.3%2.1%
February2.6%3.2%5.1%9.6%
March21%28%31%33%
April34%36%35%37%
May39%42%45%45%
June38%37%38%35%
July33%29%25%21%
August19%16%15%14%
September13%13%13%13%
October14%15%14%12%
November9.0%5.8%3.5%2.5%
December2.4%1.9%2.1%2.4%

Neighboring states

  • Indiana: arrives early February, 1 week earlier than Illinois
  • Wisconsin: arrives late February, 2 weeks later than Illinois
  • Michigan: arrives mid February, 1 week later than Illinois
  • Iowa: arrives late February, 2 weeks later than Illinois

Common questions

When do Common Grackles arrive in Illinois?
Common Grackles reach Illinois in the second week of February, are common by early March, peak in mid May (44% of checklists), and most are gone by mid October.
When do Common Grackles leave Illinois?
Most Common Grackles have left Illinois by mid October, when reports fall below half their usual rate. Stragglers are still reported until late November.
When is the best time to see a Common Grackle in Illinois?
The Common Grackle is reported most often in mid May, on about 44% of Illinois checklists.
Where in Illinois are Common Grackles seen most often?
By county, Knox County, Iroquois County, and Bureau County have the highest peak reporting rates for the Common Grackle (counties with at least 200 checklists).