WhenToBird

Stelgidopteryx serripennis · Hirundinidae

When Do Northern Rough-winged Swallows Arrive in Maryland?

Adult Northern Rough-winged Swallow
Photo: Peter Chen 2.0, CC BY 4.0 via iNaturalist

Northern Rough-winged Swallows reach Maryland in mid March, are common by late March, peak in late April (12% of checklists), and most are gone by late August.

When to look

First arrivalsMar 15-21mid March
Common byMar 22-31late March
PeakApr 22-30late April
Most gone byAug 22-31late August

Best: late April. First arrivals mid March; most are gone by late August. Peak: on about 12% of Maryland 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%5%10%15%Jan 1-7: 0% of 28716 checklistsJan 8-14: 0% of 21449 checklistsJan 15-21: 0.1% of 21267 checklistsJan 22-31: 0% of 29144 checklistsFeb 1-7: 0% of 21347 checklistsFeb 8-14: 0% of 22166 checklistsFeb 15-21: 0% of 29986 checklistsFeb 22-28: 0% of 22427 checklistsMar 1-7: 0% of 21389 checklistsMar 8-14: 0.1% of 22192 checklistsMar 15-21: 1.0% of 22823 checklistsMar 22-31: 3.8% of 33720 checklistsApr 1-7: 7.5% of 25513 checklistsApr 8-14: 9.8% of 27718 checklistsApr 15-21: 11% of 29328 checklistsApr 22-30: 12% of 42595 checklistsMay 1-7: 11% of 38532 checklistsMay 8-14: 10% of 42722 checklistsMay 15-21: 9.4% of 31936 checklistsMay 22-31: 8.6% of 36903 checklistsJun 1-7: 7.1% of 23191 checklistsJun 8-14: 6.9% of 21853 checklistsJun 15-21: 7.0% of 21000 checklistsJun 22-30: 6.6% of 25133 checklistsJul 1-7: 5.1% of 18715 checklistsJul 8-14: 4.9% of 16376 checklistsJul 15-21: 5.0% of 15793 checklistsJul 22-31: 5.6% of 21969 checklistsAug 1-7: 4.9% of 16013 checklistsAug 8-14: 4.5% of 15249 checklistsAug 15-21: 4.7% of 15674 checklistsAug 22-31: 3.5% of 24925 checklistsSep 1-7: 2.4% of 19808 checklistsSep 8-14: 1.6% of 18513 checklistsSep 15-21: 1.2% of 21901 checklistsSep 22-30: 1.4% of 22901 checklistsOct 1-7: 1.1% of 19111 checklistsOct 8-14: 0.7% of 18482 checklistsOct 15-21: 0.5% of 17380 checklistsOct 22-31: 0.2% of 23992 checklistsNov 1-7: 0.1% of 17915 checklistsNov 8-14: 0.1% of 18905 checklistsNov 15-21: 0.1% of 16259 checklistsNov 22-30: 0.1% of 22852 checklistsDec 1-7: 0% of 16108 checklistsDec 8-14: 0.1% of 16512 checklistsDec 15-21: 0.1% of 18952 checklistsDec 22-31: 0.1% of 29728 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 Maryland 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 Maryland

Best counties

Share of checklists at the peak
  1. Harford CountyBest early May · 1576 checklists that week, 39,311 in all23%
  2. Baltimore CountyBest late April · 5644 checklists that week, 136,139 in all19%
  3. Allegany CountyBest late April · 607 checklists that week, 18,322 in all19%
  4. Frederick CountyBest mid April · 1352 checklists that week, 57,576 in all15%
  5. Howard CountyBest mid April · 3116 checklists that week, 118,290 in all14%
  6. Cecil CountyBest the second week of August · 256 checklists that week, 18,620 in all13%

Best spots

Share of checklists at the peak
  1. Washington Manor ParkHoward County, best early May · 22 checklists that week, 264 in all94%
  2. Chesapeake and Ohio Canal National Historical Park (Shanty Town (historical))Allegany County, best the second week of May · 26 checklists that week, 1,096 in all89%
  3. Bladensburg Dueling GroundsPrince George's County, best early June · 31 checklists that week, 951 in all84%
  4. Brandon ShoresAnne Arundel County, best the second week of May · 29 checklists that week, 1,129 in all80%

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

Best time of day

In Maryland, the Northern Rough-winged Swallow is most often listed on checklists started between 6 and 8 am (5.6% of those checklists).

0%2%4%6%8%12 am: too few checklists (486) to judge1 am: too few checklists (451) to judge2 am: too few checklists (447) to judge3 am: too few checklists (766) to judge4 am: too few checklists (2076) to judge5 am: too few checklists (11098) to judge6 am: 7.9% of 56604 checklists7 am: 4.7% of 139255 checklists8 am: 4.1% of 148626 checklists9 am: 4.1% of 126820 checklists10 am: 3.5% of 106973 checklists11 am: 3.3% of 87483 checklists12 pm: 3.1% of 74808 checklists1 pm: 2.9% of 69428 checklists2 pm: 2.8% of 67800 checklists3 pm: 2.8% of 67688 checklists4 pm: 3.2% of 60927 checklists5 pm: 4.5% of 43876 checklists6 pm: 4.6% of 32930 checklists7 pm: too few checklists (19051) to judge8 pm: too few checklists (5708) to judge9 pm: too few checklists (1977) to judge10 pm: too few checklists (1170) to judge11 pm: too few checklists (635) 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%0.1%0%
February0%0%0%0%
March0%0.1%1.0%3.8%
April7.5%9.8%11%12%
May11%10%9.4%8.6%
June7.1%6.9%7.0%6.6%
July5.1%4.9%5.0%5.6%
August4.9%4.5%4.7%3.5%
September2.4%1.6%1.2%1.4%
October1.1%0.7%0.5%0.2%
November0.1%0.1%0.1%0.1%
December0%0.1%0.1%0.1%

Neighboring states

  • District of Columbia: arrives mid March, in the same week than Maryland
  • Delaware: arrives late March, 1 week later than Maryland
  • Virginia: arrives mid March, in the same week than Maryland
  • Pennsylvania: arrives mid March, in the same week than Maryland

Common questions

When do Northern Rough-winged Swallows arrive in Maryland?
Northern Rough-winged Swallows reach Maryland in mid March, are common by late March, peak in late April (12% of checklists), and most are gone by late August.
When do Northern Rough-winged Swallows leave Maryland?
Most Northern Rough-winged Swallows have left Maryland by late August, when reports fall below half their usual rate. Stragglers are still reported until early October.
When is the best time to see a Northern Rough-winged Swallow in Maryland?
The Northern Rough-winged Swallow is reported most often in late April, on about 12% of Maryland checklists.
Where in Maryland are Northern Rough-winged Swallows seen most often?
By county, Harford County, Baltimore County, and Allegany County have the highest peak reporting rates for the Northern Rough-winged Swallow (counties with at least 200 checklists).