Maryland mammals

Common Bottlenose Dolphin in Maryland

Tursiops truncatus

Native to Maryland S4 Apparently Secure in Maryland

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

IUCN Red List status

LC – Least Concern

Widespread and abundant; not at risk.

Photo: NASA · Public domainCommon Bottlenose Dolphin (Tursiops truncatus)Photo: Diego Delso · CC BY-SA 4.0Delfín mular (Tursiops truncatus), isla de San Cristóbal, islas Galápagos, Ecuador, 2015-07-24, DD 86Photo: Jonathan Eisen · CC BY 4.0Common Bottlenose Dolphin (Tursiops truncatus)Photo: steve b · CC0Two wild bottlenose dolphins breaching in unison over gray coastal waterPhoto: Rolf Lawrenz · CC BY 4.0Wild bottlenose dolphin surfacing head-on, beak and dorsal fin above the water

Photo: NASA · Public domainCommon Bottlenose Dolphin (Tursiops truncatus)Photo: Diego Delso · CC BY-SA 4.0Delfín mular (Tursiops truncatus), isla de San Cristóbal, islas Galápagos, Ecuador, 2015-07-24, DD 86Photo: Jonathan Eisen · CC BY 4.0Common Bottlenose Dolphin (Tursiops truncatus)Photo: steve b · CC0Two wild bottlenose dolphins breaching in unison over gray coastal waterPhoto: Rolf Lawrenz · CC BY 4.0Wild bottlenose dolphin surfacing head-on, beak and dorsal fin above the water

Common Bottlenose Dolphin in Maryland, by the numbers

Common in Maryland 27th most recorded of 100 mammals logged in Maryland

148 occurrence records

Records from 2000–2026.

When to look for the Common Bottlenose Dolphin in Maryland

Most sightings fall in August.

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

Monthly Maryland records (table)

Month	Records
January	1
February	1
March	1
April	3
May	42
June	20
July	13
August	50
September	14
October	1
November	1
December	1

Monthly common bottlenose dolphin occurrence records (iNaturalist and GBIF) in Maryland, 2000–2026.

Seasonality

Year-round in Maryland, with recorded sightings peaking in August, with a smaller rise in May.

Occurrence map

Where Common Bottlenose Dolphin has been recorded in Maryland

148 records mapped · zoom and drag to explore

144 Maryland records mapped

Where it's recorded in Maryland

County	Records
Worcester County	47
Somerset County	7
Kent County	3
St. Mary's County	1
Other localities	90

The complete county distribution, spread across 4 Maryland counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Common bottlenose dolphin sightings in Maryland cluster around Assateague Island’s coastal waters and the tidal reaches near Blackwater and Eastern Neck refuges, consistent with a coastal-resident population that regularly moves into the lower Chesapeake Bay and its river mouths to feed. Reports here reflect boat- and shore-based sightings rather than any dedicated marine survey effort.

Records peak from August through September, tracking the warm-water months when dolphins push furthest up the bay in pursuit of migrating fish. NatureServe ranks the species S4, Apparently Secure, in Maryland waters.

Full species profile Common Bottlenose Dolphin Tursiops truncatus Size 2–4 m6.6–13.1 ft Weight 150–650 kg330.7–1433 lb Lifespan 60 yr View the full profile

More mammals in Maryland in the atlas

Data & sources

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

GBIFCC-BY 4.0occurrence records behind the range map, elevation, and record counts
iNaturalistCC0 / CC-BY / CC-BY-SAobservations, photos, and audio recordings
NatureServe ExplorerCC-BYthe state conservation rank
IUCN Red Listattributed factthe global conservation status
USGS NASpublic domainnative / introduced status
Natural Earthpublic domainthe relief basemap
USFSpublic domainnational-forest boundaries