WhenToBird

Hydroprogne caspia · Laridae

When Do Caspian Terns Arrive in Vermont?

Adult Caspian Tern
Photo: Daughter Dad, CC BY 4.0 via iNaturalist

Caspian Terns reach Vermont in early April, are common by the second week of April, peak in the second week of August (8.8% of checklists), and most are gone by the second week of September.

When to look

First arrivalsApr 1-7early April
Common byApr 8-14the second week of April
PeakAug 8-14the second week of August
Most gone bySep 8-14the second week of September

Best: the second week of August. First arrivals early April; most are gone by the second week of September. Peak: on about 8.8% of Vermont checklists.

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

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

0%5%10%Jan 1-7: 0% of 12234 checklistsJan 8-14: 0% of 8293 checklistsJan 15-21: 0% of 7885 checklistsJan 22-31: 0% of 10534 checklistsFeb 1-7: 0% of 7212 checklistsFeb 8-14: 0% of 8144 checklistsFeb 15-21: 0% of 10480 checklistsFeb 22-28: 0% of 7932 checklistsMar 1-7: 0% of 8192 checklistsMar 8-14: 0% of 9383 checklistsMar 15-21: 0.1% of 10620 checklistsMar 22-31: 0.1% of 16257 checklistsApr 1-7: 1.0% of 12568 checklistsApr 8-14: 2.1% of 14677 checklistsApr 15-21: 2.9% of 14106 checklistsApr 22-30: 3.2% of 19617 checklistsMay 1-7: 3.1% of 18143 checklistsMay 8-14: 2.5% of 19626 checklistsMay 15-21: 3.1% of 17779 checklistsMay 22-31: 3.9% of 20310 checklistsJun 1-7: 3.8% of 11493 checklistsJun 8-14: 4.2% of 10215 checklistsJun 15-21: 3.9% of 9951 checklistsJun 22-30: 3.8% of 11050 checklistsJul 1-7: 3.7% of 8690 checklistsJul 8-14: 4.2% of 7679 checklistsJul 15-21: 5.1% of 7687 checklistsJul 22-31: 7.1% of 10712 checklistsAug 1-7: 8.1% of 7703 checklistsAug 8-14: 9.0% of 7743 checklistsAug 15-21: 9.3% of 8314 checklistsAug 22-31: 6.8% of 12428 checklistsSep 1-7: 3.9% of 9526 checklistsSep 8-14: 1.4% of 8493 checklistsSep 15-21: 0.5% of 8283 checklistsSep 22-30: 0.1% of 10352 checklistsOct 1-7: 0.1% of 8802 checklistsOct 8-14: 0.1% of 9088 checklistsOct 15-21: 0% of 7739 checklistsOct 22-31: 0% of 10907 checklistsNov 1-7: 0% of 7868 checklistsNov 8-14: 0% of 7223 checklistsNov 15-21: 0% of 7224 checklistsNov 22-30: 0% of 8375 checklistsDec 1-7: 0% of 6580 checklistsDec 8-14: 0% of 6800 checklistsDec 15-21: 0% of 8334 checklistsDec 22-31: 0% of 10579 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 Vermont 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 Vermont

Best counties

Share of checklists at the peak
  1. Franklin CountyBest mid August · 526 checklists that week, 25,284 in all27%
  2. Chittenden CountyBest the second week of August · 1523 checklists that week, 109,477 in all26%
  3. Grand Isle CountyBest early August · 140 checklists that week, 8,507 in all24%
  4. Addison CountyBest the second week of August · 1263 checklists that week, 77,064 in all12%
  5. Windham CountyBest early May · 1903 checklists that week, 39,105 in all0.5%
  6. Rutland CountyBest the second week of August · 685 checklists that week, 46,909 in all0.4%

Best spots

Share of checklists at the peak
  1. La Platte RiverChittenden County, best late July · 99 checklists that week, 4,615 in all86%
  2. Shelburne PondChittenden County, best late May · 51 checklists that week, 819 in all79%
  3. Charcoal CreekFranklin County, best early May · 39 checklists that week, 868 in all77%
  4. Goose BayFranklin County, best early September · 21 checklists that week, 213 in all77%

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

Best time of day

In Vermont, the Caspian Tern is most often listed on checklists started between 5 and 7 am (3.9% of those checklists).

0%2%4%6%12 am: too few checklists (384) to judge1 am: too few checklists (418) to judge2 am: too few checklists (568) to judge3 am: too few checklists (1183) to judge4 am: too few checklists (3460) to judge5 am: 4.6% of 10340 checklists6 am: 3.6% of 30951 checklists7 am: 1.7% of 64150 checklists8 am: 1.5% of 70252 checklists9 am: 1.7% of 55280 checklists10 am: 2.0% of 47111 checklists11 am: 2.0% of 37615 checklists12 pm: 1.9% of 32195 checklists1 pm: 2.1% of 30185 checklists2 pm: 2.2% of 29679 checklists3 pm: 2.6% of 26483 checklists4 pm: 2.6% of 20110 checklists5 pm: 3.2% of 15993 checklists6 pm: 3.8% of 12110 checklists7 pm: too few checklists (8203) to judge8 pm: too few checklists (4425) to judge9 pm: too few checklists (1829) to judge10 pm: too few checklists (597) to judge11 pm: too few checklists (309) 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%0.1%0.1%
April1.0%2.1%2.9%3.2%
May3.1%2.5%3.1%3.9%
June3.8%4.2%3.9%3.8%
July3.7%4.2%5.1%7.1%
August8.1%9.0%9.3%6.8%
September3.9%1.4%0.5%0.1%
October0.1%0.1%0%0%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Rhode Island: arrives the second week of June, 9 weeks later than Vermont
  • New York: arrives the second week of April, 1 week later than Vermont
  • New Jersey: arrives mid July, 14 weeks later than Vermont
  • Pennsylvania: arrives the second week of July, 13 weeks later than Vermont

Common questions

When do Caspian Terns arrive in Vermont?
Caspian Terns reach Vermont in early April, are common by the second week of April, peak in the second week of August (8.8% of checklists), and most are gone by the second week of September.
When do Caspian Terns leave Vermont?
Most Caspian Terns have left Vermont by the second week of September, when reports fall below half their usual rate.
When is the best time to see a Caspian Tern in Vermont?
The Caspian Tern is reported most often in the second week of August, on about 8.8% of Vermont checklists.
Where in Vermont are Caspian Terns seen most often?
By county, Franklin County, Chittenden County, and Grand Isle County have the highest peak reporting rates for the Caspian Tern (counties with at least 200 checklists).