Delaware mammals

Harbor Seal in Delaware

Phoca vitulina

Native to Delaware

Not listed as nonindigenous in Delaware by USGS NAS; native to its Delaware range.

IUCN Red List status

  1. LC
  2. NT
  3. VU
  4. EN
  5. CR
  6. EW
  7. EX

LC – Least Concern

Widespread and abundant; not at risk.

Common seal (Phoca vitulina) 2Harbor seal (Phoca vitulina) at Magdalen fjord, Svalbard (2)Common seal (Phoca vitulina)Harbor seal (Phoca vitulina) at Magdalen fjord, Svalbard (1)SeehundHarbor Seal (Phoca vitulina)
Photo: Charles J. Sharp · CC BY-SA 4.0Common seal (Phoca vitulina) 2Photo: AWeith · CC BY-SA 4.0Harbor seal (Phoca vitulina) at Magdalen fjord, Svalbard (2)Photo: Charles J. Sharp · CC BY-SA 4.0Common seal (Phoca vitulina)Photo: AWeith · CC BY-SA 4.0Harbor seal (Phoca vitulina) at Magdalen fjord, Svalbard (1)Photo: Marcel Burkhard · CC BY-SA 2.0 deSeehundPhoto: Andrea · CC BY 4.0Harbor Seal (Phoca vitulina)

Harbor Seal in Delaware, by the numbers

Common in Delaware 13th most recorded of 62 mammals logged in Delaware

119 occurrence records
119 with iNaturalist photos
Mar 29, 2026 Last seen in Delaware

Records from 2000–2026.

When to look for the Harbor Seal in Delaware

Most sightings fall in March.

119 Delaware occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence.

Monthly Delaware records (table)
MonthRecords
January31
February24
March47
April4
May0
June0
July0
August0
September0
October0
November1
December12

Monthly harbor seal occurrence records (iNaturalist and GBIF) in Delaware, 2000–2026.

Seasonality

Year-round in Delaware, with recorded sightings peaking in March, with a smaller rise in January.

Occurrence map

Where Harbor Seal has been recorded in Delaware

119 records mapped · zoom and drag to explore

119 Delaware records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Delaware Bay shoreline 6
Delaware Seashore State Park 2

Protected places with the most harbor seal sightings, from the USGS Protected Areas Database plus named mountain ranges, good spots to look, not a full breakdown, so they don't sum to the total.

Where it's recorded in Delaware

CountyRecords
Sussex County 43
Kent County 1
Other localities 75

The complete county distribution, spread across 2 Delaware counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Harbor Seals are cool-season visitors to Delaware Bay and the Atlantic coast, not typical summer beach residents. From Cape Henlopen, scan offshore bars, breakwaters, and quiet water near the bay mouth with binoculars; a hauled-out seal may resemble a dark log until it lifts its head.

Records peak from January through March. A seal resting ashore is not automatically stranded: keep people and dogs well back and contact the regional stranding network if it appears injured or disturbed.

Occurrence data from iNaturalist and GBIF.

Common seal (Phoca vitulina) 2
Full species profile Harbor Seal Phoca vitulina Size 1.4–1.9 m4.6–6.2 ft Weight 55–170 kg121.3–374.8 lb Lifespan Up to 47.6 yr View the full profile

More mammals in Delaware in the atlas

Data & sources

The data and visualizations on this page draw on these open sources: