When do ospreys leave Wisconsin?

Most Ospreys have left Wisconsin by late September, when reports fall below half their usual rate. Stragglers are still reported until early October.

When is the best time to see ospreys in Wisconsin?

The Osprey is reported most often in mid August, on about 6.4% of Wisconsin checklists.

Osprey · Pandion haliaetus

When Do Ospreys Arrive in Wisconsin?

Photo: Bill Levine, CC BY 4.0 via iNaturalist

Ospreys reach Wisconsin in late March, are common by early April, peak in mid August (6.4% of checklists), and most are gone by late September.

When to look

First arrivalsMar 22-31late March

Common byApr 1-7early April

PeakAug 15-21mid August

Most gone bySep 22-30late September

Best: mid August. First arrivals late March; most are gone by late September. Peak: on about 6.4% of Wisconsin checklists.

Jannot usually seen
Febnot usually seen
Maruncommon
Aprpeak season
Maypeak season
Juncommon
Julpeak season
Augpeak season
Seppeak season
Octuncommon
Novrare
Decnot usually seen

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

Ospreys in Wisconsin, species by species

Species	First arrivals	Common by	Peak	Most gone by	Peak %
Osprey	Mar 22-31	Apr 1-7	Aug 15-21	Sep 22-30	6.4%

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 Wisconsin 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 Wisconsin

Best counties for Osprey

Share of checklists at the peak

Winnebago CountyBest mid August · 378 checklists that week, 26,460 in all28%
Calumet CountyBest early May · 797 checklists that week, 12,359 in all23%
Marquette CountyBest the second week of August · 55 checklists that week, 3,706 in all22%
Kewaunee CountyBest early August · 137 checklists that week, 9,747 in all22%
Barron CountyBest late August · 116 checklists that week, 6,745 in all21%
Manitowoc CountyBest late July · 425 checklists that week, 26,017 in all20%

Common questions

When do ospreys arrive in Wisconsin?: Ospreys reach Wisconsin in late March, are common by early April, peak in mid August (6.4% of checklists), and most are gone by late September.
When do ospreys leave Wisconsin?: Most Ospreys have left Wisconsin by late September, when reports fall below half their usual rate. Stragglers are still reported until early October.
When is the best time to see ospreys in Wisconsin?: The Osprey is reported most often in mid August, on about 6.4% of Wisconsin checklists.