WhenToBird

Sternula antillarum · Laridae

When Do Least Terns Arrive in Maine?

Adult Least Tern
Photo: datadan, CC BY 4.0 via iNaturalist

Least Terns arrive in Maine in mid May, peak in mid July (3.6% of checklists), and most are gone by the second week of August.

When to look

First arrivalsMay 15-21mid May
Common byMay 15-21mid May
PeakJul 15-21mid July
Most gone byAug 8-14the second week of August

Best: mid July. First arrivals mid May; most are gone by the second week of August. Peak: on about 3.6% of Maine checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Aprnot usually seen
  5. Maycommon
  6. Juncommon
  7. Julpeak season
  8. Augcommon
  9. Sepnot usually seen
  10. Octnot usually seen
  11. Novnot usually seen
  12. Decnot usually seen

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

0%2%4%6%Jan 1-7: 0% of 15499 checklistsJan 8-14: 0% of 11141 checklistsJan 15-21: 0% of 10729 checklistsJan 22-31: 0% of 15084 checklistsFeb 1-7: 0% of 9403 checklistsFeb 8-14: 0% of 11268 checklistsFeb 15-21: 0% of 14061 checklistsFeb 22-28: 0% of 9977 checklistsMar 1-7: 0% of 9649 checklistsMar 8-14: 0% of 11781 checklistsMar 15-21: 0% of 11613 checklistsMar 22-31: 0% of 17798 checklistsApr 1-7: 0% of 14638 checklistsApr 8-14: 0% of 16511 checklistsApr 15-21: 0% of 17164 checklistsApr 22-30: 0% of 22602 checklistsMay 1-7: 0.1% of 22556 checklistsMay 8-14: 0.8% of 27842 checklistsMay 15-21: 1.9% of 27748 checklistsMay 22-31: 2.3% of 38715 checklistsJun 1-7: 2.4% of 26916 checklistsJun 8-14: 2.4% of 23737 checklistsJun 15-21: 2.5% of 22733 checklistsJun 22-30: 2.2% of 28248 checklistsJul 1-7: 3.1% of 20290 checklistsJul 8-14: 3.4% of 18534 checklistsJul 15-21: 4.1% of 17319 checklistsJul 22-31: 3.4% of 22815 checklistsAug 1-7: 2.5% of 15004 checklistsAug 8-14: 1.5% of 14603 checklistsAug 15-21: 0.9% of 14972 checklistsAug 22-31: 0.3% of 19813 checklistsSep 1-7: 0.1% of 14567 checklistsSep 8-14: 0.1% of 14520 checklistsSep 15-21: 0% of 14339 checklistsSep 22-30: 0% of 16879 checklistsOct 1-7: 0% of 12959 checklistsOct 8-14: 0% of 13168 checklistsOct 15-21: 0% of 11184 checklistsOct 22-31: 0% of 13717 checklistsNov 1-7: 0% of 9823 checklistsNov 8-14: 0% of 9007 checklistsNov 15-21: 0% of 8528 checklistsNov 22-30: 0% of 10228 checklistsDec 1-7: 0% of 7505 checklistsDec 8-14: 0% of 7982 checklistsDec 15-21: 0% of 10455 checklistsDec 22-31: 0% of 14285 checklistsJanFebMarAprMayJunJulAugSepOctNovDec
Share of complete checklists reporting it, by week (4 per month). Grey bars: fewer than 10 checklists, not counted.

Frequency is the share of complete checklists in Maine 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.

JanFebMarAprMayJunJulAugSepOctNovDec
today
Second week of November

Each county is shaded by the share of complete checklists there that listed the bird, blended with the weeks either side. Darker is more often. It follows where people watch birds, not how many birds there are. How to read it.

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Where in Maine

Best counties

Share of checklists at the peak
  1. York CountyBest the second week of July · 1947 checklists that week, 101,844 in all15%
  2. Cumberland CountyBest the second week of July · 3137 checklists that week, 169,501 in all10%
  3. Sagadahoc CountyBest mid July · 500 checklists that week, 21,736 in all8.6%
  4. Knox CountyBest the second week of June · 1089 checklists that week, 34,453 in all0.1%
  5. Lincoln CountyBest early September · 1206 checklists that week, 59,429 in all0.1%

Best spots

Share of checklists at the peak
  1. Parsons BeachYork County, best mid July · 33 checklists that week, 1,272 in all95%
  2. Higgins BeachCumberland County, best late May · 34 checklists that week, 624 in all88%
  3. Stratton IslandYork County, best late June · 24 checklists that week, 353 in all76%
  4. Wells National Estuarine Research ReserveYork County, best the second week of July · 141 checklists that week, 4,555 in all64%
  5. Webhannet River MarshYork County, best mid July · 39 checklists that week, 1,758 in all63%
  6. Popham Beach State ParkSagadahoc County, best the second week of July · 22 checklists that week, 749 in all63%

Busy spots report more of everything; compare the checklist counts before you drive anywhere.

Best time of day

In Maine, the Least Tern is most often listed on checklists started between 5 and 7 pm (1.4% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (510) to judge1 am: too few checklists (517) to judge2 am: too few checklists (581) to judge3 am: too few checklists (3242) to judge4 am: too few checklists (7221) to judge5 am: 1.5% of 19895 checklists6 am: 1.1% of 54578 checklists7 am: 1.1% of 92775 checklists8 am: 1.0% of 86962 checklists9 am: 0.9% of 78989 checklists10 am: 0.9% of 70954 checklists11 am: 0.8% of 59331 checklists12 pm: 0.8% of 50943 checklists1 pm: 0.9% of 49775 checklists2 pm: 0.9% of 49001 checklists3 pm: 1.1% of 43252 checklists4 pm: 1.1% of 33413 checklists5 pm: 1.3% of 25547 checklists6 pm: 1.5% of 18309 checklists7 pm: too few checklists (14287) to judge8 pm: too few checklists (5336) to judge9 pm: too few checklists (2253) to judge10 pm: too few checklists (1518) to judge11 pm: too few checklists (720) to judge12a3a6a9a12p3p6p9p
Share of checklists started in each local hour that reported it. It reflects when people go birding as well as when birds are active. Grey hours have too few checklists (under 2% of the state’s, or under 200) to judge.
Week-by-week table
MonthDays 1-78-1415-2122-end
January0%0%0%0%
February0%0%0%0%
March0%0%0%0%
April0%0%0%0%
May0.1%0.8%1.9%2.3%
June2.4%2.4%2.5%2.2%
July3.1%3.4%4.1%3.4%
August2.5%1.5%0.9%0.3%
September0.1%0.1%0%0%
October0%0%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

Common questions

When do Least Terns arrive in Maine?
Least Terns arrive in Maine in mid May, peak in mid July (3.6% of checklists), and most are gone by the second week of August.
When do Least Terns leave Maine?
Most Least Terns have left Maine by the second week of August, when reports fall below half their usual rate.
When is the best time to see a Least Tern in Maine?
The Least Tern is reported most often in mid July, on about 3.6% of Maine checklists.
Where in Maine are Least Terns seen most often?
By county, York County, Cumberland County, and Sagadahoc County have the highest peak reporting rates for the Least Tern (counties with at least 200 checklists).