WhenToBird

Hydroprogne caspia · Laridae

When Do Caspian Terns Arrive in Missouri?

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

Caspian Terns arrive in Missouri in the second week of July, peak in early September (1.7% of checklists), and most are gone by early October.

When to look

First arrivalsJul 8-14the second week of July
Common byJul 8-14the second week of July
PeakSep 1-7early September
Most gone byOct 1-7early October

Best: early September. First arrivals the second week of July; most are gone by early October. Peak: on about 1.7% of Missouri checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marnot usually seen
  4. Apruncommon
  5. Maycommon
  6. Junrare
  7. Julcommon
  8. Augpeak season
  9. Seppeak season
  10. Octuncommon
  11. Novnot usually seen
  12. Decnot usually seen

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

0%0.5%1%1.5%2%Jan 1-7: 0% of 12628 checklistsJan 8-14: 0% of 9076 checklistsJan 15-21: 0% of 8790 checklistsJan 22-31: 0% of 11986 checklistsFeb 1-7: 0% of 8987 checklistsFeb 8-14: 0% of 10394 checklistsFeb 15-21: 0% of 15472 checklistsFeb 22-28: 0% of 9917 checklistsMar 1-7: 0% of 9877 checklistsMar 8-14: 0% of 9570 checklistsMar 15-21: 0% of 10274 checklistsMar 22-31: 0.1% of 16156 checklistsApr 1-7: 0.1% of 12774 checklistsApr 8-14: 0.1% of 14048 checklistsApr 15-21: 0.4% of 14894 checklistsApr 22-30: 0.7% of 23288 checklistsMay 1-7: 0.7% of 22645 checklistsMay 8-14: 0.6% of 21384 checklistsMay 15-21: 0.6% of 13989 checklistsMay 22-31: 0.3% of 15784 checklistsJun 1-7: 0.1% of 9691 checklistsJun 8-14: 0.2% of 9036 checklistsJun 15-21: 0.1% of 7907 checklistsJun 22-30: 0.1% of 9831 checklistsJul 1-7: 0.2% of 8008 checklistsJul 8-14: 0.4% of 7202 checklistsJul 15-21: 0.7% of 7151 checklistsJul 22-31: 0.9% of 9833 checklistsAug 1-7: 0.6% of 7639 checklistsAug 8-14: 1.0% of 7507 checklistsAug 15-21: 1.0% of 7429 checklistsAug 22-31: 1.6% of 11182 checklistsSep 1-7: 1.8% of 9471 checklistsSep 8-14: 1.6% of 8501 checklistsSep 15-21: 1.4% of 8169 checklistsSep 22-30: 0.9% of 11572 checklistsOct 1-7: 0.3% of 9028 checklistsOct 8-14: 0.1% of 9413 checklistsOct 15-21: 0.1% of 8656 checklistsOct 22-31: 0.1% of 11625 checklistsNov 1-7: 0% of 8627 checklistsNov 8-14: 0% of 8284 checklistsNov 15-21: 0% of 8075 checklistsNov 22-30: 0% of 10430 checklistsDec 1-7: 0% of 7870 checklistsDec 8-14: 0% of 7567 checklistsDec 15-21: 0% of 9696 checklistsDec 22-31: 0% of 13142 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 Missouri 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 Missouri

Best counties

Share of checklists at the peak
  1. Putnam CountyBest late August · 13 checklists that week, 790 in all30%
  2. Monroe CountyBest early September · 30 checklists that week, 1,048 in all25%
  3. Polk CountyBest the second week of September · 21 checklists that week, 1,429 in all18%
  4. Clinton CountyBest early September · 20 checklists that week, 1,615 in all16%
  5. Macon CountyBest early September · 18 checklists that week, 1,377 in all15%
  6. Benton CountyBest the second week of September · 58 checklists that week, 3,579 in all15%

Best spots

Share of checklists at the peak
  1. Smithville LakeClay County, best late August · 26 checklists that week, 598 in all48%
  2. Longview LakeJackson County, best early September · 31 checklists that week, 2,343 in all30%
  3. Lake RemoteClay County, best late September · 36 checklists that week, 898 in all30%
  4. Otter Slough Conservation AreaStoddard County, best late August · 21 checklists that week, 326 in all28%
  5. Alton SloughSt. Charles County, best late July · 190 checklists that week, 7,626 in all25%

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

Best time of day

In Missouri, the Caspian Tern is most often listed on checklists started between 3 and 5 pm (0.5% of those checklists).

0%0.5%12 am: too few checklists (205) to judge1 am: too few checklists (179) to judge2 am: too few checklists (204) to judge3 am: too few checklists (216) to judge4 am: too few checklists (630) to judge5 am: too few checklists (5072) to judge6 am: 0.4% of 27231 checklists7 am: 0.2% of 64162 checklists8 am: 0.3% of 67854 checklists9 am: 0.3% of 56515 checklists10 am: 0.3% of 47496 checklists11 am: 0.4% of 38845 checklists12 pm: 0.4% of 33383 checklists1 pm: 0.5% of 32503 checklists2 pm: 0.4% of 32615 checklists3 pm: 0.5% of 32514 checklists4 pm: 0.5% of 30274 checklists5 pm: 0.5% of 23446 checklists6 pm: 0.4% of 16374 checklists7 pm: too few checklists (10236) to judge8 pm: too few checklists (3133) to judge9 pm: too few checklists (722) to judge10 pm: too few checklists (405) to judge11 pm: too few checklists (261) 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%0.1%
April0.1%0.1%0.4%0.7%
May0.7%0.6%0.6%0.3%
June0.1%0.2%0.1%0.1%
July0.2%0.4%0.7%0.9%
August0.6%1.0%1.0%1.6%
September1.8%1.6%1.4%0.9%
October0.3%0.1%0.1%0.1%
November0%0%0%0%
December0%0%0%0%

Neighboring states

  • Iowa: arrives late July, 2 weeks later than Missouri
  • Kansas: arrives early August, 3 weeks later than Missouri
  • Illinois: arrives late March, 14 weeks earlier than Missouri
  • Indiana: arrives late March, 14 weeks earlier than Missouri

Common questions

When do Caspian Terns arrive in Missouri?
Caspian Terns arrive in Missouri in the second week of July, peak in early September (1.7% of checklists), and most are gone by early October.
When do Caspian Terns leave Missouri?
Most Caspian Terns have left Missouri by early October, when reports fall below half their usual rate.
When is the best time to see a Caspian Tern in Missouri?
The Caspian Tern is reported most often in early September, on about 1.7% of Missouri checklists.
Where in Missouri are Caspian Terns seen most often?
By county, Putnam County, Monroe County, and Polk County have the highest peak reporting rates for the Caspian Tern (counties with at least 200 checklists).