WhenToBird

2 grosbeak species in Illinois

When Do Grosbeaks Arrive in Illinois?

Adult male Rose-breasted Grosbeak
Photo: Nancy Overholtz, CC BY-SA 4.0 via iNaturalist

Rose-breasted Grosbeaks and Blue Grosbeaks are the grosbeaks you are most likely to see in Illinois. Rose-breasted Grosbeaks reach Illinois in mid April, are common by late April, peak in the second week of May (28% of checklists), and most are gone by early October.

When to look

First arrivalsApr 15-21mid April
Common byApr 22-30late April
PeakMay 8-14the second week of May
Most gone byOct 1-7early October

Best: the second week of May. First arrivals mid April; most are gone by early October. Peak: on about 28% of Illinois checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprcommon
  5. Maypeak season
  6. Juncommon
  7. Juluncommon
  8. Auguncommon
  9. Sepcommon
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

Grosbeaks in Illinois, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
Rose-breasted GrosbeakApr 15-21Apr 22-30May 8-14Oct 1-728%
Blue GrosbeakApr 22-30May 1-7Jul 22-31Sep 1-73.3%
0%10%20%30%40%Rose-breasted GrosbeakBlue GrosbeakJanFebMarAprMayJunJulAugSepOctNovDec
  • Rose-breasted Grosbeak
  • Blue Grosbeak
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 Rose-breasted Grosbeak

Share of checklists at the peak
  1. Schuyler CountyBest the second week of May · 27 checklists that week, 617 in all70%
  2. Monroe CountyBest the second week of May · 90 checklists that week, 2,547 in all62%
  3. Putnam CountyBest mid May · 45 checklists that week, 3,333 in all59%
  4. Stark CountyBest the second week of May · 27 checklists that week, 574 in all57%
  5. Mercer CountyBest mid May · 15 checklists that week, 949 in all55%
  6. Mason CountyBest the second week of May · 208 checklists that week, 5,020 in all49%

Common questions

When do grosbeaks arrive in Illinois?
Rose-breasted Grosbeaks reach Illinois in mid April, are common by late April, peak in the second week of May (28% of checklists), and most are gone by early October.
When do grosbeaks leave Illinois?
Most Rose-breasted Grosbeaks have left Illinois by early October, when reports fall below half their usual rate. Stragglers are still reported until the second week of October.
When is the best time to see grosbeaks in Illinois?
The Rose-breasted Grosbeak is reported most often in the second week of May, on about 28% of Illinois checklists.
Which grosbeaks are in Illinois?
Rose-breasted Grosbeak and Blue Grosbeak are reported regularly; the Rose-breasted Grosbeak is the most common.