Eastern Bluebirds are in Illinois all year, but most are here in fall: numbers build from the second week of September, peak in mid October (13% of checklists), and fall back by the second week of November. In the quietest week (mid January) they are still on about 4.2% of checklists.
When to look
Numbers buildSep 8-14the second week of September
PeakOct 15-21mid October
Fall back byNov 8-14the second week of November
FewestJan 15-21mid January
Best: mid October. Here all year; numbers build from the second week of September and fall back by the second week of November. Peak: on about 13% of Illinois checklists.
Januncommon
Febcommon
Marpeak season
Aprpeak season
Maypeak season
Junpeak season
Julpeak season
Augcommon
Seppeak season
Octpeak season
Novpeak season
Deccommon
Darker months: more checklists report it. Outlined: peak month.
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
0%few checklistsno data
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.
Sugar RiverWinnebago County, best late May · 29 checklists that week, 372 in all80%
Watershed Nature CenterMadison County, best the second week of April · 22 checklists that week, 973 in all79%
Heron Creek 1Lake County, best the second week of May · 40 checklists that week, 569 in all78%
Busy spots report more of everything; compare the checklist counts before you drive anywhere.
Best time of day
In Illinois, the Eastern Bluebird is most often listed on checklists started between 6 and 8 am (13% of those checklists).
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
Eastern Bluebirds are in Illinois all year, but most are here in fall: numbers build from the second week of September, peak in mid October (13% of checklists), and fall back by the second week of November. In the quietest week (mid January) they are still on about 4.2% of checklists.
When do Eastern Bluebirds leave Illinois?
Eastern Bluebirds never fully leave Illinois: numbers fall back below half their usual rate by the second week of November, but some are still reported in every week, about 4.2% of checklists at the low.
When is the best time to see a Eastern Bluebird in Illinois?
The Eastern Bluebird is reported most often in mid October, on about 13% of Illinois checklists.
Where in Illinois are Eastern Bluebirds seen most often?
By county, Wabash County, Wayne County, and Massac County have the highest peak reporting rates for the Eastern Bluebird (counties with at least 200 checklists).