WhenToBird

2 grosbeak species in Delaware

When Do Grosbeaks Arrive in Delaware?

Adult male Blue Grosbeak
Photo: John Rosford, CC BY 4.0 via iNaturalist

Blue Grosbeaks and Rose-breasted Grosbeaks are the grosbeaks you are most likely to see in Delaware. Blue Grosbeaks reach Delaware in mid April, are common by early May, peak in early August (23% of checklists), and most are gone by mid September.

When to look

First arrivalsApr 15-21mid April
Common byMay 1-7early May
PeakAug 1-7early August
Most gone bySep 15-21mid September

Best: early August. First arrivals mid April; most are gone by mid September. Peak: on about 23% of Delaware checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Apruncommon
  5. Maycommon
  6. Junpeak season
  7. Julpeak season
  8. Augpeak season
  9. Sepcommon
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

Grosbeaks in Delaware, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
Blue GrosbeakApr 15-21May 1-7Aug 1-7Sep 15-2123%
Rose-breasted GrosbeakSep 1-7Sep 1-7Sep 15-21Oct 8-145.1%
0%10%20%30%Blue GrosbeakRose-breasted GrosbeakJanFebMarAprMayJunJulAugSepOctNovDec
  • Blue Grosbeak
  • Rose-breasted 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 Delaware 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 Delaware

Best counties for Blue Grosbeak

Share of checklists at the peak
  1. Sussex CountyBest early August · 1800 checklists that week, 91,027 in all29%
  2. Kent CountyBest the second week of August · 980 checklists that week, 36,693 in all29%
  3. New Castle CountyBest mid August · 1045 checklists that week, 72,140 in all7.6%

Common questions

When do grosbeaks arrive in Delaware?
Blue Grosbeaks reach Delaware in mid April, are common by early May, peak in early August (23% of checklists), and most are gone by mid September.
When do grosbeaks leave Delaware?
Most Blue Grosbeaks have left Delaware by mid September, when reports fall below half their usual rate. Stragglers are still reported until early October.
When is the best time to see grosbeaks in Delaware?
The Blue Grosbeak is reported most often in early August, on about 23% of Delaware checklists.
Which grosbeaks are in Delaware?
Blue Grosbeak and Rose-breasted Grosbeak are reported regularly; the Blue Grosbeak is the most common.