WhenToBird

Hydroprogne caspia · Laridae

When Do Caspian Terns Arrive in Indiana?

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

Caspian Terns reach Indiana in late March, are common by early April, peak in the second week of August (5.6% of checklists), and most are gone by mid September.

When to look

First arrivalsMar 22-31late March
Common byApr 1-7early April
PeakAug 8-14the second week of August
Most gone bySep 15-21mid September

Best: the second week of August. First arrivals late March; most are gone by mid September. Peak: on about 5.6% of Indiana checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Maruncommon
  4. Aprcommon
  5. Maycommon
  6. Jununcommon
  7. Julpeak season
  8. Augpeak season
  9. Sepcommon
  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% of 18123 checklistsJan 8-14: 0% of 12006 checklistsJan 15-21: 0% of 12403 checklistsJan 22-31: 0% of 16181 checklistsFeb 1-7: 0% of 12546 checklistsFeb 8-14: 0% of 14250 checklistsFeb 15-21: 0% of 18077 checklistsFeb 22-28: 0% of 13590 checklistsMar 1-7: 0.1% of 14545 checklistsMar 8-14: 0% of 14594 checklistsMar 15-21: 0.1% of 13894 checklistsMar 22-31: 0.8% of 22400 checklistsApr 1-7: 2.0% of 18069 checklistsApr 8-14: 2.6% of 19579 checklistsApr 15-21: 3.0% of 19518 checklistsApr 22-30: 2.4% of 30544 checklistsMay 1-7: 2.1% of 28430 checklistsMay 8-14: 2.7% of 30624 checklistsMay 15-21: 3.5% of 22920 checklistsMay 22-31: 2.0% of 21234 checklistsJun 1-7: 1.4% of 12279 checklistsJun 8-14: 1.5% of 10904 checklistsJun 15-21: 2.1% of 9488 checklistsJun 22-30: 2.1% of 11362 checklistsJul 1-7: 2.4% of 9947 checklistsJul 8-14: 3.8% of 9585 checklistsJul 15-21: 4.0% of 8929 checklistsJul 22-31: 4.5% of 12639 checklistsAug 1-7: 5.1% of 9528 checklistsAug 8-14: 6.0% of 9451 checklistsAug 15-21: 5.8% of 9442 checklistsAug 22-31: 4.2% of 14969 checklistsSep 1-7: 3.7% of 12628 checklistsSep 8-14: 2.4% of 11793 checklistsSep 15-21: 1.1% of 11396 checklistsSep 22-30: 0.7% of 14203 checklistsOct 1-7: 0.3% of 11365 checklistsOct 8-14: 0.2% of 12092 checklistsOct 15-21: 0.1% of 10440 checklistsOct 22-31: 0.1% of 13883 checklistsNov 1-7: 0.1% of 10476 checklistsNov 8-14: 0% of 9776 checklistsNov 15-21: 0% of 9035 checklistsNov 22-30: 0% of 12547 checklistsDec 1-7: 0% of 9078 checklistsDec 8-14: 0% of 8732 checklistsDec 15-21: 0% of 11024 checklistsDec 22-31: 0% of 15432 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 Indiana 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 Indiana

Best counties

Share of checklists at the peak
  1. Lake CountyBest early August · 349 checklists that week, 22,199 in all56%
  2. LaPorte CountyBest mid July · 260 checklists that week, 12,564 in all37%
  3. Gibson CountyBest early September · 272 checklists that week, 10,754 in all35%
  4. Jasper CountyBest late July · 32 checklists that week, 1,586 in all19%
  5. Union CountyBest mid August · 96 checklists that week, 4,811 in all17%
  6. Clinton CountyBest the second week of September · 10 checklists that week, 900 in all15%

Best spots

Share of checklists at the peak
  1. Wolf LakeLake County, best the second week of August · 22 checklists that week, 489 in all96%
  2. Washington Park / Michigan CityLaPorte County, best early May · 26 checklists that week, 2,145 in all94%
  3. Marquette ParkLake County, best late June · 23 checklists that week, 1,474 in all93%
  4. Marquette Park (east)Lake County, best late April · 22 checklists that week, 1,400 in all88%
  5. Carlson/Oxbow ParkLake County, best late July · 29 checklists that week, 470 in all87%

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

Best time of day

In Indiana, the Caspian Tern is most often listed on checklists started between 6 and 8 am (2.7% of those checklists).

0%2%4%6%12 am: too few checklists (240) to judge1 am: too few checklists (231) to judge2 am: too few checklists (222) to judge3 am: too few checklists (202) to judge4 am: too few checklists (674) to judge5 am: too few checklists (4329) to judge6 am: 5.0% of 20589 checklists7 am: 1.9% of 58470 checklists8 am: 1.2% of 86931 checklists9 am: 1.2% of 78239 checklists10 am: 1.2% of 66080 checklists11 am: 1.3% of 54904 checklists12 pm: 1.3% of 47610 checklists1 pm: 1.7% of 44814 checklists2 pm: 1.4% of 43790 checklists3 pm: 1.3% of 42983 checklists4 pm: 1.3% of 45349 checklists5 pm: 1.6% of 35993 checklists6 pm: 1.8% of 26447 checklists7 pm: 1.3% of 17740 checklists8 pm: too few checklists (7603) to judge9 pm: too few checklists (1721) to judge10 pm: too few checklists (517) to judge11 pm: too few checklists (272) 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%
March0.1%0%0.1%0.8%
April2.0%2.6%3.0%2.4%
May2.1%2.7%3.5%2.0%
June1.4%1.5%2.1%2.1%
July2.4%3.8%4.0%4.5%
August5.1%6.0%5.8%4.2%
September3.7%2.4%1.1%0.7%
October0.3%0.2%0.1%0.1%
November0.1%0%0%0%
December0%0%0%0%

Neighboring states

  • Illinois: arrives late March, in the same week than Indiana
  • Kentucky: arrives mid July, 15 weeks later than Indiana
  • Ohio: arrives early April, 1 week later than Indiana
  • Michigan: arrives the second week of April, 2 weeks later than Indiana

Common questions

When do Caspian Terns arrive in Indiana?
Caspian Terns reach Indiana in late March, are common by early April, peak in the second week of August (5.6% of checklists), and most are gone by mid September.
When do Caspian Terns leave Indiana?
Most Caspian Terns have left Indiana by mid September, when reports fall below half their usual rate.
When is the best time to see a Caspian Tern in Indiana?
The Caspian Tern is reported most often in the second week of August, on about 5.6% of Indiana checklists.
Where in Indiana are Caspian Terns seen most often?
By county, Lake County, LaPorte County, and Gibson County have the highest peak reporting rates for the Caspian Tern (counties with at least 200 checklists).