WhenToBird

Osprey · Pandion haliaetus

When Do Ospreys Arrive in Delaware?

Adult female Osprey
Photo: Bill Levine, CC BY 4.0 via iNaturalist

Ospreys reach Delaware in the second week of March, are common by mid March, peak in late July (43% of checklists), and most are gone by late September.

When to look

First arrivalsMar 8-14the second week of March
Common byMar 15-21mid March
PeakJul 22-31late July
Most gone bySep 22-30late September

Best: late July. First arrivals the second week of March; most are gone by late September. Peak: on about 43% of Delaware checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marcommon
  4. Aprpeak season
  5. Maypeak season
  6. Junpeak season
  7. Julpeak season
  8. Augpeak season
  9. Sepcommon
  10. Octuncommon
  11. Novrare
  12. Decnot usually seen

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

Ospreys in Delaware, species by species

SpeciesFirst arrivalsCommon byPeakMost gone byPeak %
OspreyMar 8-14Mar 15-21Jul 22-31Sep 22-3043%
0%20%40%60%OspreyJanFebMarAprMayJunJulAugSepOctNovDec
  • Osprey
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 Osprey

Share of checklists at the peak
  1. Sussex CountyBest early August · 1800 checklists that week, 91,027 in all60%
  2. Kent CountyBest mid July · 735 checklists that week, 36,693 in all41%
  3. New Castle CountyBest the second week of April · 1835 checklists that week, 72,140 in all21%

Common questions

When do ospreys arrive in Delaware?
Ospreys reach Delaware in the second week of March, are common by mid March, peak in late July (43% of checklists), and most are gone by late September.
When do ospreys leave Delaware?
Most Ospreys have left Delaware by late September, when reports fall below half their usual rate. Stragglers are still reported until early November.
When is the best time to see ospreys in Delaware?
The Osprey is reported most often in late July, on about 43% of Delaware checklists.