When do loons leave Pennsylvania?

Most Common Loons have left Pennsylvania by mid May, when reports fall below half their usual rate.

When is the best time to see loons in Pennsylvania?

The Common Loon is reported most often in the second week of April, on about 5.0% of Pennsylvania checklists.

Common Loon · Gavia immer

When Do Loons Arrive in Pennsylvania?

Photo: Hungry-Sarracenia Photo, CC BY 4.0 via iNaturalist

Common Loons arrive in Pennsylvania in mid March, peak in the second week of April (5.0% of checklists), and most are gone by mid May. They are the only regular loons in Pennsylvania.

When to look

First arrivalsMar 15-21mid March

Common byMar 15-21mid March

PeakApr 8-14the second week of April

Most gone byMay 15-21mid May

Best: the second week of April. First arrivals mid March; most are gone by mid May. Peak: on about 5.0% of Pennsylvania checklists.

Janrare
Febrare
Marcommon
Aprpeak season
Maycommon
Junrare
Julnot usually seen
Augnot usually seen
Sepnot usually seen
Octuncommon
Novuncommon
Decuncommon

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

Loons in Pennsylvania, species by species

Species	First arrivals	Common by	Peak	Most gone by	Peak %
Common Loon	Mar 15-21	Mar 15-21	Apr 8-14	May 15-21	5.0%

Common Loon

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 Pennsylvania 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 Pennsylvania

Best counties for Common Loon

Share of checklists at the peak

Carbon CountyBest the second week of April · 480 checklists that week, 16,269 in all29%
Erie CountyBest the second week of November · 738 checklists that week, 49,012 in all20%
Mercer CountyBest early April · 553 checklists that week, 17,853 in all18%
Clearfield CountyBest the second week of April · 299 checklists that week, 9,768 in all17%
Montour CountyBest the second week of April · 198 checklists that week, 6,082 in all17%
Venango CountyBest early April · 74 checklists that week, 2,831 in all16%

Common questions

When do loons arrive in Pennsylvania?: Common Loons arrive in Pennsylvania in mid March, peak in the second week of April (5.0% of checklists), and most are gone by mid May. They are the only regular loons in Pennsylvania.
When do loons leave Pennsylvania?: Most Common Loons have left Pennsylvania by mid May, when reports fall below half their usual rate.
When is the best time to see loons in Pennsylvania?: The Common Loon is reported most often in the second week of April, on about 5.0% of Pennsylvania checklists.