When do grackles and blackbirds leave Illinois?

Red-winged Blackbirds never fully leave Illinois: numbers fall back below half their usual rate by early August, but some are still reported in every week, about 3.5% of checklists at the low.

When is the best time to see grackles and blackbirds in Illinois?

The Red-winged Blackbird is reported most often in mid May, on about 65% of Illinois checklists.

Which grackles and blackbirds are in Illinois?

Red-winged Blackbird, Brown-headed Cowbird, Common Grackle, Eastern Meadowlark, Bobolink, and Rusty Blackbird are reported regularly; the Red-winged Blackbird is the most common.

6 blackbird species in Illinois

When Do Grackles and blackbirds Arrive in Illinois?

Photo: infiniteuniverse, CC0 1.0 via iNaturalist

Red-winged Blackbirds, Brown-headed Cowbirds, and Common Grackles are the grackles and blackbirds you are most likely to see in Illinois. Red-winged Blackbirds are in Illinois all year, but most are here in spring: numbers build from late February, peak in mid May (65% of checklists), and fall back by early August. In the quietest week (the second week of January) they are still on about 3.5% of checklists.

When to look

Numbers buildFeb 22-28late February

PeakMay 15-21mid May

Fall back byAug 1-7early August

FewestJan 8-14the second week of January

Best: mid May. Here all year; numbers build from late February and fall back by early August. Peak: on about 65% of Illinois checklists.

Janrare
Febcommon
Marpeak season
Aprpeak season
Maypeak season
Junpeak season
Julpeak season
Augcommon
Sepuncommon
Octcommon
Novuncommon
Decrare

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

Grackles and blackbirds in Illinois, species by species

Species	First arrivals	Common by	Peak	Most gone by	Peak %
Red-winged Blackbird	Feb 22-28	Feb 22-28	May 15-21	Aug 1-7	65%
Brown-headed Cowbird	Feb 15-21	Mar 22-31	May 1-7	Jul 15-21	45%
Common Grackle	Feb 8-14	Mar 1-7	May 15-21	Oct 15-21	44%
Eastern Meadowlark	Feb 15-21	Mar 1-7	Jun 8-14	Aug 1-7	13%
Bobolink	May 1-7	May 1-7	Jun 8-14	Jul 8-14	5.8%
Rusty Blackbird	Feb 22-28	Feb 22-28	Apr 1-7	Apr 22-30	3.9%

Red-winged Blackbird
Brown-headed Cowbird
Common Grackle
Eastern Meadowlark

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 Red-winged Blackbird

Share of checklists at the peak

Greene CountyBest the second week of June · 40 checklists that week, 329 in all92%
Putnam CountyBest mid April · 55 checklists that week, 3,333 in all89%
Scott CountyBest early July · 20 checklists that week, 320 in all88%
Ford CountyBest early June · 14 checklists that week, 762 in all86%
Stark CountyBest mid June · 14 checklists that week, 574 in all86%
Grundy CountyBest early June · 93 checklists that week, 5,050 in all85%

Common questions

When do grackles and blackbirds arrive in Illinois?: Red-winged Blackbirds are in Illinois all year, but most are here in spring: numbers build from late February, peak in mid May (65% of checklists), and fall back by early August. In the quietest week (the second week of January) they are still on about 3.5% of checklists.
When do grackles and blackbirds leave Illinois?: Red-winged Blackbirds never fully leave Illinois: numbers fall back below half their usual rate by early August, but some are still reported in every week, about 3.5% of checklists at the low.
When is the best time to see grackles and blackbirds in Illinois?: The Red-winged Blackbird is reported most often in mid May, on about 65% of Illinois checklists.
Which grackles and blackbirds are in Illinois?: Red-winged Blackbird, Brown-headed Cowbird, Common Grackle, Eastern Meadowlark, Bobolink, and Rusty Blackbird are reported regularly; the Red-winged Blackbird is the most common.