WhenToBird

Hydroprogne caspia · Laridae

When Do Caspian Terns Arrive in District of Columbia?

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

Caspian Terns arrive in District of Columbia in mid July, peak in early September (7.0% of checklists), and most are gone by mid October.

When to look

First arrivalsJul 15-21mid July
Common byJul 15-21mid July
PeakSep 1-7early September
Most gone byOct 15-21mid October

Best: early September. First arrivals mid July; most are gone by mid October. Peak: on about 7.0% of District of Columbia checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Aprcommon
  5. Mayuncommon
  6. Junrare
  7. Julcommon
  8. Augpeak season
  9. Seppeak season
  10. Octcommon
  11. Novrare
  12. Decnot usually seen

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

0%2%4%6%8%Jan 1-7: 0% of 3043 checklistsJan 8-14: 0% of 2367 checklistsJan 15-21: 0% of 2140 checklistsJan 22-31: 0% of 2777 checklistsFeb 1-7: 0% of 2012 checklistsFeb 8-14: 0% of 1997 checklistsFeb 15-21: 0% of 2544 checklistsFeb 22-28: 0% of 2252 checklistsMar 1-7: 0% of 2282 checklistsMar 8-14: 0% of 2350 checklistsMar 15-21: 0% of 2432 checklistsMar 22-31: 0.3% of 3898 checklistsApr 1-7: 2.5% of 3221 checklistsApr 8-14: 6.3% of 3396 checklistsApr 15-21: 6.6% of 3718 checklistsApr 22-30: 3.5% of 5725 checklistsMay 1-7: 1.8% of 5415 checklistsMay 8-14: 0.8% of 5268 checklistsMay 15-21: 0.2% of 3741 checklistsMay 22-31: 0.6% of 3605 checklistsJun 1-7: 0.4% of 1902 checklistsJun 8-14: 0.1% of 1762 checklistsJun 15-21: 0.4% of 1637 checklistsJun 22-30: 0.4% of 1727 checklistsJul 1-7: 0.1% of 1471 checklistsJul 8-14: 1.1% of 1353 checklistsJul 15-21: 1.5% of 1297 checklistsJul 22-31: 2.7% of 1980 checklistsAug 1-7: 5.3% of 1465 checklistsAug 8-14: 6.5% of 1311 checklistsAug 15-21: 5.6% of 1669 checklistsAug 22-31: 5.7% of 2631 checklistsSep 1-7: 7.9% of 2482 checklistsSep 8-14: 7.3% of 2622 checklistsSep 15-21: 3.3% of 2661 checklistsSep 22-30: 3.3% of 3393 checklistsOct 1-7: 3.8% of 2457 checklistsOct 8-14: 3.5% of 2487 checklistsOct 15-21: 0.8% of 2201 checklistsOct 22-31: 0.9% of 2639 checklistsNov 1-7: 0.2% of 2074 checklistsNov 8-14: 0% of 1967 checklistsNov 15-21: 0% of 1832 checklistsNov 22-30: 0% of 2064 checklistsDec 1-7: 0% of 1773 checklistsDec 8-14: 0% of 2132 checklistsDec 15-21: 0% of 2009 checklistsDec 22-31: 0% of 2574 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 District of Columbia 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 District of Columbia

Best counties

Share of checklists at the peak
  1. District of Columbia CountyBest early September · 2481 checklists that week, 121,721 in all7.0%

Best spots

Share of checklists at the peak
  1. Goose IslandDistrict of Columbia County, best the second week of September · 26 checklists that week, 403 in all92%
  2. George Washington Memorial ParkwayDistrict of Columbia County, best the second week of September · 113 checklists that week, 1,054 in all76%
  3. Franklin Delano Roosevelt MemorialDistrict of Columbia County, best the second week of September · 30 checklists that week, 1,969 in all55%
  4. National Capital ParksDistrict of Columbia County, best late August · 108 checklists that week, 6,880 in all42%
  5. Chesapeake and Ohio Canal National Historical ParkDistrict of Columbia County, best mid April · 105 checklists that week, 2,253 in all21%
  6. Lyndon Baines Johnson Memorial Grove on the PotomacDistrict of Columbia County, best late September · 26 checklists that week, 1,852 in all16%

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

Best time of day

In District of Columbia, the Caspian Tern is most often listed on checklists started between 6 and 8 am (3.0% of those checklists).

0%2%4%6%12 am: too few checklists (27) to judge1 am: too few checklists (29) to judge2 am: too few checklists (23) to judge3 am: too few checklists (21) to judge4 am: too few checklists (31) to judge5 am: too few checklists (631) to judge6 am: 4.6% of 7391 checklists7 am: 2.4% of 18497 checklists8 am: 1.3% of 18527 checklists9 am: 1.5% of 13285 checklists10 am: 1.5% of 10722 checklists11 am: 1.7% of 8880 checklists12 pm: 1.2% of 7456 checklists1 pm: 1.4% of 6394 checklists2 pm: 1.6% of 6063 checklists3 pm: 1.6% of 6112 checklists4 pm: 1.4% of 5809 checklists5 pm: 1.9% of 5409 checklists6 pm: 2.0% of 3982 checklists7 pm: too few checklists (1887) to judge8 pm: too few checklists (423) to judge9 pm: too few checklists (79) to judge10 pm: too few checklists (44) to judge11 pm: too few checklists (33) 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%0.3%
April2.5%6.3%6.6%3.5%
May1.8%0.8%0.2%0.6%
June0.4%0.1%0.4%0.4%
July0.1%1.1%1.5%2.7%
August5.3%6.5%5.6%5.7%
September7.9%7.3%3.3%3.3%
October3.8%3.5%0.8%0.9%
November0.2%0%0%0%
December0%0%0%0%

Neighboring states

  • Maryland: arrives mid July, in the same week than District of Columbia
  • Virginia: arrives the second week of July, 1 week earlier than District of Columbia
  • Delaware: arrives early April, 14 weeks earlier than District of Columbia
  • Pennsylvania: arrives the second week of July, 1 week earlier than District of Columbia

Common questions

When do Caspian Terns arrive in District of Columbia?
Caspian Terns arrive in District of Columbia in mid July, peak in early September (7.0% of checklists), and most are gone by mid October.
When do Caspian Terns leave District of Columbia?
Most Caspian Terns have left District of Columbia by mid October, when reports fall below half their usual rate.
When is the best time to see a Caspian Tern in District of Columbia?
The Caspian Tern is reported most often in early September, on about 7.0% of District of Columbia checklists.
Where in District of Columbia are Caspian Terns seen most often?
By county, District of Columbia County have the highest peak reporting rates for the Caspian Tern (counties with at least 200 checklists).