WhenToBird

Sterna forsteri · Laridae

When Do Forster's Terns Arrive in Missouri?

Adult Forster's Tern
Photo: Aitor, CC BY 4.0 via iNaturalist

Forster's Terns arrive in Missouri in the second week of April, peak in late April (1.5% of checklists), and most are gone by mid May.

When to look

First arrivalsApr 8-14the second week of April
Common byApr 8-14the second week of April
PeakApr 22-30late April
Most gone byMay 15-21mid May

Best: late April. First arrivals the second week of April; most are gone by mid May. Peak: on about 1.5% of Missouri checklists.

  1. Jannot usually seen
  2. Febnot usually seen
  3. Marrare
  4. Aprpeak season
  5. Maypeak season
  6. Jununcommon
  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%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: 0.1% 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: 0.4% of 14048 checklistsApr 15-21: 1.2% of 14894 checklistsApr 22-30: 1.7% of 23288 checklistsMay 1-7: 1.6% of 22645 checklistsMay 8-14: 1.0% of 21384 checklistsMay 15-21: 0.7% of 13989 checklistsMay 22-31: 0.4% of 15784 checklistsJun 1-7: 0.2% of 9691 checklistsJun 8-14: 0.1% of 9036 checklistsJun 15-21: 0.1% of 7907 checklistsJun 22-30: 0.2% of 9831 checklistsJul 1-7: 0.4% of 8008 checklistsJul 8-14: 0.6% of 7202 checklistsJul 15-21: 1.0% of 7151 checklistsJul 22-31: 1.3% of 9833 checklistsAug 1-7: 1.0% of 7639 checklistsAug 8-14: 1.4% of 7507 checklistsAug 15-21: 1.4% of 7429 checklistsAug 22-31: 1.4% of 11182 checklistsSep 1-7: 1.2% of 9471 checklistsSep 8-14: 1.4% of 8501 checklistsSep 15-21: 1.2% of 8169 checklistsSep 22-30: 1.1% of 11572 checklistsOct 1-7: 0.7% of 9028 checklistsOct 8-14: 0.6% of 9413 checklistsOct 15-21: 0.4% of 8656 checklistsOct 22-31: 0.3% of 11625 checklistsNov 1-7: 0.2% of 8627 checklistsNov 8-14: 0.1% of 8284 checklistsNov 15-21: 0.1% of 8075 checklistsNov 22-30: 0% of 10430 checklistsDec 1-7: 0% of 7870 checklistsDec 8-14: 0% of 7567 checklistsDec 15-21: 0.1% 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. Clinton CountyBest early September · 20 checklists that week, 1,615 in all23%
  2. Monroe CountyBest mid September · 53 checklists that week, 1,048 in all23%
  3. Nodaway CountyBest late August · 24 checklists that week, 834 in all18%
  4. Putnam CountyBest late August · 13 checklists that week, 790 in all15%
  5. Macon CountyBest mid September · 24 checklists that week, 1,377 in all14%
  6. Polk CountyBest mid July · 24 checklists that week, 1,429 in all13%

Best spots

Share of checklists at the peak
  1. Smithville LakeClay County, best late August · 26 checklists that week, 598 in all63%
  2. Horseshoe LakeBuchanan County, best late July · 25 checklists that week, 664 in all35%
  3. Fellows LakeGreene County, best late April · 35 checklists that week, 1,227 in all33%
  4. Lake Springfield ParkGreene County, best late April · 174 checklists that week, 2,219 in all31%

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

Best time of day

In Missouri, the Forster's Tern is most often listed on checklists started between 4 and 6 pm (0.8% of those checklists).

0%0.5%1%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: 0.6% of 27231 checklists7 am: 0.3% of 64162 checklists8 am: 0.3% of 67854 checklists9 am: 0.5% of 56515 checklists10 am: 0.5% of 47496 checklists11 am: 0.6% of 38845 checklists12 pm: 0.7% of 33383 checklists1 pm: 0.7% of 32503 checklists2 pm: 0.7% of 32615 checklists3 pm: 0.8% of 32514 checklists4 pm: 0.7% of 30274 checklists5 pm: 0.8% of 23446 checklists6 pm: 0.6% 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%0.1%
March0%0%0%0.1%
April0.1%0.4%1.2%1.7%
May1.6%1.0%0.7%0.4%
June0.2%0.1%0.1%0.2%
July0.4%0.6%1.0%1.3%
August1.0%1.4%1.4%1.4%
September1.2%1.4%1.2%1.1%
October0.7%0.6%0.4%0.3%
November0.2%0.1%0.1%0%
December0%0%0.1%0%

Neighboring states

  • Arkansas: arrives early July, 11 weeks later than Missouri
  • Iowa: arrives mid April, 1 week later than Missouri
  • Kansas: arrives the second week of July, 12 weeks later than Missouri
  • Illinois: arrives mid April, 1 week later than Missouri

Common questions

When do Forster's Terns arrive in Missouri?
Forster's Terns arrive in Missouri in the second week of April, peak in late April (1.5% of checklists), and most are gone by mid May.
When do Forster's Terns leave Missouri?
Most Forster's Terns have left Missouri by mid May, when reports fall below half their usual rate.
When is the best time to see a Forster's Tern in Missouri?
The Forster's Tern is reported most often in late April, on about 1.5% of Missouri checklists.
Where in Missouri are Forster's Terns seen most often?
By county, Clinton County, Monroe County, and Nodaway County have the highest peak reporting rates for the Forster's Tern (counties with at least 200 checklists).