WhenToBird

Thalasseus sandvicensis · Laridae

When Do Sandwich Terns Arrive in Louisiana?

Adult Sandwich Tern
Photo: Roy Lowry, CC BY 4.0 via iNaturalist

Sandwich Terns arrive in Louisiana in late March, peak in mid April (4.6% of checklists), and most are gone by the second week of September.

When to look

First arrivalsMar 22-31late March
Common byMar 22-31late March
PeakApr 15-21mid April
Most gone bySep 8-14the second week of September

Best: mid April. First arrivals late March; most are gone by the second week of September. Peak: on about 4.6% of Louisiana checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprpeak season
  5. Maypeak season
  6. Juncommon
  7. Julcommon
  8. Augcommon
  9. Sepuncommon
  10. Octrare
  11. Novnot usually seen
  12. Decnot usually seen

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

0%2%4%6%Jan 1-7: 0.1% of 8384 checklistsJan 8-14: 0% of 6265 checklistsJan 15-21: 0.1% of 6825 checklistsJan 22-31: 0% of 8776 checklistsFeb 1-7: 0.1% of 5956 checklistsFeb 8-14: 0.1% of 6291 checklistsFeb 15-21: 0.1% of 8044 checklistsFeb 22-28: 0.1% of 5946 checklistsMar 1-7: 0.1% of 5981 checklistsMar 8-14: 0.1% of 6307 checklistsMar 15-21: 0.6% of 6747 checklistsMar 22-31: 1.6% of 10487 checklistsApr 1-7: 2.5% of 8037 checklistsApr 8-14: 3.9% of 9577 checklistsApr 15-21: 5.0% of 11372 checklistsApr 22-30: 4.9% of 14344 checklistsMay 1-7: 3.1% of 8193 checklistsMay 8-14: 2.2% of 6823 checklistsMay 15-21: 2.0% of 4818 checklistsMay 22-31: 2.5% of 6206 checklistsJun 1-7: 1.9% of 3660 checklistsJun 8-14: 1.9% of 3455 checklistsJun 15-21: 1.5% of 3084 checklistsJun 22-30: 1.9% of 3904 checklistsJul 1-7: 1.1% of 3240 checklistsJul 8-14: 2.3% of 3235 checklistsJul 15-21: 1.7% of 3167 checklistsJul 22-31: 3.0% of 4328 checklistsAug 1-7: 1.7% of 3192 checklistsAug 8-14: 1.7% of 3394 checklistsAug 15-21: 1.6% of 3502 checklistsAug 22-31: 2.4% of 5658 checklistsSep 1-7: 1.3% of 4366 checklistsSep 8-14: 1.2% of 4648 checklistsSep 15-21: 1.1% of 4369 checklistsSep 22-30: 0.6% of 6418 checklistsOct 1-7: 0.3% of 5375 checklistsOct 8-14: 0.4% of 6213 checklistsOct 15-21: 0.2% of 5553 checklistsOct 22-31: 0.3% of 8879 checklistsNov 1-7: 0.1% of 6231 checklistsNov 8-14: 0.1% of 5011 checklistsNov 15-21: 0.1% of 4856 checklistsNov 22-30: 0.1% of 6696 checklistsDec 1-7: 0.1% of 4530 checklistsDec 8-14: 0.1% of 4883 checklistsDec 15-21: 0.1% of 5833 checklistsDec 22-31: 0.1% of 9940 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 Louisiana 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.

Embed this map on your site

Where in Louisiana

Best counties

Share of checklists at the peak
  1. Plaquemines ParishBest the second week of June · 32 checklists that week, 3,374 in all33%
  2. St. Bernard ParishBest late May · 14 checklists that week, 1,331 in all28%
  3. Cameron ParishBest mid July · 81 checklists that week, 17,943 in all19%
  4. Jefferson ParishBest early May · 813 checklists that week, 25,795 in all16%
  5. Lafourche ParishBest mid April · 169 checklists that week, 4,021 in all13%
  6. Terrebonne ParishBest the second week of May · 144 checklists that week, 6,857 in all9.5%

Best spots

Share of checklists at the peak
  1. Grand Isle State ParkJefferson Parish, best late May · 22 checklists that week, 944 in all78%
  2. Bayou Thunder Von TrancJefferson Parish, best late April · 63 checklists that week, 675 in all75%
  3. Bayou Thunder Von Tranc (Cheniere Caminada)Jefferson Parish, best late April · 35 checklists that week, 483 in all59%
  4. State Lands (southwest)Cameron Parish, best late April · 27 checklists that week, 129 in all56%

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

Best time of day

In Louisiana, the Sandwich Tern is most often listed on checklists started between 1 and 3 pm (1.8% of those checklists).

0%0.5%1%1.5%2%12 am: too few checklists (110) to judge1 am: too few checklists (95) to judge2 am: too few checklists (78) to judge3 am: too few checklists (145) to judge4 am: too few checklists (266) to judge5 am: too few checklists (2981) to judge6 am: 0.9% of 21115 checklists7 am: 1.0% of 38843 checklists8 am: 1.2% of 36306 checklists9 am: 1.3% of 31934 checklists10 am: 1.5% of 27208 checklists11 am: 1.6% of 20733 checklists12 pm: 1.5% of 18505 checklists1 pm: 1.7% of 17383 checklists2 pm: 1.9% of 17422 checklists3 pm: 1.3% of 17005 checklists4 pm: 1.2% of 17170 checklists5 pm: 1.3% of 12536 checklists6 pm: 1.5% of 8080 checklists7 pm: too few checklists (3798) to judge8 pm: too few checklists (676) to judge9 pm: too few checklists (311) to judge10 pm: too few checklists (206) to judge11 pm: too few checklists (93) 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
January0.1%0%0.1%0%
February0.1%0.1%0.1%0.1%
March0.1%0.1%0.6%1.6%
April2.5%3.9%5.0%4.9%
May3.1%2.2%2.0%2.5%
June1.9%1.9%1.5%1.9%
July1.1%2.3%1.7%3.0%
August1.7%1.7%1.6%2.4%
September1.3%1.2%1.1%0.6%
October0.3%0.4%0.2%0.3%
November0.1%0.1%0.1%0.1%
December0.1%0.1%0.1%0.1%

Neighboring states

  • Mississippi: arrives the second week of April, 2 weeks later than Louisiana
  • Alabama: arrives late March, in the same week than Louisiana
  • Texas: arrives the second week of March, 2 weeks earlier than Louisiana
  • Georgia: arrives early April, 1 week later than Louisiana

Common questions

When do Sandwich Terns arrive in Louisiana?
Sandwich Terns arrive in Louisiana in late March, peak in mid April (4.6% of checklists), and most are gone by the second week of September.
When do Sandwich Terns leave Louisiana?
Most Sandwich Terns have left Louisiana by the second week of September, when reports fall below half their usual rate.
When is the best time to see a Sandwich Tern in Louisiana?
The Sandwich Tern is reported most often in mid April, on about 4.6% of Louisiana checklists.
Where in Louisiana are Sandwich Terns seen most often?
By county, Plaquemines Parish, St. Bernard Parish, and Cameron Parish have the highest peak reporting rates for the Sandwich Tern (counties with at least 200 checklists).