WhenToBird

Sterna forsteri · Laridae

When Do Forster's Terns Arrive in Oklahoma?

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

Forster's Terns reach Oklahoma in the second week of July, are common by mid July, peak in the second week of August (5.0% of checklists), and most are gone by the second week of January.

When to look

First arrivalsJul 8-14the second week of July
Common byJul 15-21mid July
PeakAug 8-14the second week of August
Most gone byJan 8-14the second week of January

Best: the second week of August. First arrivals the second week of July; most are gone by the second week of January. Peak: on about 5.0% of Oklahoma checklists.

  1. Januncommon
  2. Febrare
  3. Marrare
  4. Aprpeak season
  5. Maypeak season
  6. Jununcommon
  7. Julcommon
  8. Augpeak season
  9. Seppeak season
  10. Octpeak season
  11. Novcommon
  12. Deccommon

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

0%2%4%6%Jan 1-7: 1.2% of 6087 checklistsJan 8-14: 1.7% of 4350 checklistsJan 15-21: 1.3% of 4381 checklistsJan 22-31: 0.9% of 6165 checklistsFeb 1-7: 0.5% of 4259 checklistsFeb 8-14: 0.4% of 4589 checklistsFeb 15-21: 0.1% of 7001 checklistsFeb 22-28: 0.4% of 4482 checklistsMar 1-7: 0.4% of 4724 checklistsMar 8-14: 0.5% of 4571 checklistsMar 15-21: 0.9% of 4393 checklistsMar 22-31: 0.6% of 7544 checklistsApr 1-7: 0.9% of 5967 checklistsApr 8-14: 1.3% of 6543 checklistsApr 15-21: 2.8% of 7366 checklistsApr 22-30: 4.1% of 10618 checklistsMay 1-7: 4.7% of 8835 checklistsMay 8-14: 3.0% of 8247 checklistsMay 15-21: 2.8% of 6081 checklistsMay 22-31: 1.7% of 7283 checklistsJun 1-7: 0.7% of 4256 checklistsJun 8-14: 0.4% of 3774 checklistsJun 15-21: 0.6% of 3541 checklistsJun 22-30: 0.5% of 4159 checklistsJul 1-7: 0.6% of 3209 checklistsJul 8-14: 1.1% of 2916 checklistsJul 15-21: 1.9% of 2861 checklistsJul 22-31: 3.6% of 4146 checklistsAug 1-7: 4.1% of 3043 checklistsAug 8-14: 5.3% of 2839 checklistsAug 15-21: 5.6% of 3014 checklistsAug 22-31: 4.1% of 4759 checklistsSep 1-7: 4.4% of 3861 checklistsSep 8-14: 4.3% of 3748 checklistsSep 15-21: 4.0% of 3569 checklistsSep 22-30: 4.0% of 4830 checklistsOct 1-7: 4.0% of 3809 checklistsOct 8-14: 3.7% of 4142 checklistsOct 15-21: 3.2% of 3705 checklistsOct 22-31: 3.3% of 4738 checklistsNov 1-7: 3.0% of 3823 checklistsNov 8-14: 2.3% of 3849 checklistsNov 15-21: 2.1% of 3722 checklistsNov 22-30: 2.4% of 4795 checklistsDec 1-7: 1.8% of 3324 checklistsDec 8-14: 2.1% of 3574 checklistsDec 15-21: 2.1% of 3884 checklistsDec 22-31: 1.4% of 5774 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 Oklahoma 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 Oklahoma

Best counties

Share of checklists at the peak
  1. McIntosh CountyBest late December · 13 checklists that week, 511 in all32%
  2. Marshall CountyBest mid April · 11 checklists that week, 590 in all26%
  3. Blaine CountyBest the second week of September · 11 checklists that week, 732 in all24%
  4. Pittsburg CountyBest mid December · 14 checklists that week, 603 in all20%
  5. Delaware CountyBest early November · 12 checklists that week, 1,727 in all17%
  6. Wagoner CountyBest the second week of August · 24 checklists that week, 2,059 in all17%

Best spots

Share of checklists at the peak
  1. Lake Thunderbird State ParkCleveland County, best mid August · 29 checklists that week, 824 in all88%
  2. CLO LandsPayne County, best late August · 30 checklists that week, 1,208 in all67%
  3. Lake Hefner (Lansbrook Lake)Oklahoma County, best the second week of September · 41 checklists that week, 743 in all61%
  4. Lake Hefner (NW Oklahoma City Sludge Lagoon)Oklahoma County, best late July · 34 checklists that week, 295 in all51%
  5. Edmond ParkOklahoma County, best late October · 26 checklists that week, 792 in all48%
  6. Lake Hefner (northeast)Oklahoma County, best early January · 34 checklists that week, 807 in all43%

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

Best time of day

In Oklahoma, the Forster's Tern is most often listed on checklists started between 2 and 4 pm (2.5% of those checklists).

0%1%2%3%12 am: too few checklists (91) to judge1 am: too few checklists (65) to judge2 am: too few checklists (73) to judge3 am: too few checklists (73) to judge4 am: too few checklists (100) to judge5 am: too few checklists (647) to judge6 am: 1.9% of 8353 checklists7 am: 2.1% of 24509 checklists8 am: 2.3% of 27848 checklists9 am: 2.3% of 25316 checklists10 am: 2.3% of 21161 checklists11 am: 2.5% of 18730 checklists12 pm: 2.0% of 16097 checklists1 pm: 2.3% of 14028 checklists2 pm: 2.4% of 13599 checklists3 pm: 2.6% of 14228 checklists4 pm: 2.2% of 14597 checklists5 pm: 2.1% of 12125 checklists6 pm: 2.2% of 9337 checklists7 pm: 1.3% of 6944 checklists8 pm: too few checklists (2403) to judge9 pm: too few checklists (459) to judge10 pm: too few checklists (226) to judge11 pm: too few checklists (141) 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
January1.2%1.7%1.3%0.9%
February0.5%0.4%0.1%0.4%
March0.4%0.5%0.9%0.6%
April0.9%1.3%2.8%4.1%
May4.7%3.0%2.8%1.7%
June0.7%0.4%0.6%0.5%
July0.6%1.1%1.9%3.6%
August4.1%5.3%5.6%4.1%
September4.4%4.3%4.0%4.0%
October4.0%3.7%3.2%3.3%
November3.0%2.3%2.1%2.4%
December1.8%2.1%2.1%1.4%

Neighboring states

  • Kansas: arrives the second week of July, in the same week than Oklahoma
  • Arkansas: arrives early July, 1 week earlier than Oklahoma
  • Missouri: arrives the second week of April, 12 weeks earlier than Oklahoma
  • Nebraska: arrives the second week of April, 12 weeks earlier than Oklahoma

Common questions

When do Forster's Terns arrive in Oklahoma?
Forster's Terns reach Oklahoma in the second week of July, are common by mid July, peak in the second week of August (5.0% of checklists), and most are gone by the second week of January.
When do Forster's Terns leave Oklahoma?
Most Forster's Terns have left Oklahoma by the second week of January, when reports fall below half their usual rate. Stragglers are still reported until mid January.
When is the best time to see a Forster's Tern in Oklahoma?
The Forster's Tern is reported most often in the second week of August, on about 5.0% of Oklahoma checklists.
Where in Oklahoma are Forster's Terns seen most often?
By county, McIntosh County, Marshall County, and Blaine County have the highest peak reporting rates for the Forster's Tern (counties with at least 200 checklists).