Northeastern Marsh Rice Rat

Oryzomys palustris

Also known as: Marsh Rice Rat, Marsh Oryzomys

LCLeast Concern

Photo: Alex Stach · CC BY 4.0Live northeastern marsh rice rat peering out from dense dry grass and green shootsPhoto: Joseph Hubbard · CC BY 4.0Northeastern Marsh Rice Rat (Oryzomys palustris)Photo: Southeast Ecological Science Center, USGS · Public domainMarsh rice rat in profile walking across wire mesh, white feet and long tail visible

Photo: Alex Stach · CC BY 4.0Live northeastern marsh rice rat peering out from dense dry grass and green shootsPhoto: Joseph Hubbard · CC BY 4.0Northeastern Marsh Rice Rat (Oryzomys palustris)Photo: Southeast Ecological Science Center, USGS · Public domainMarsh rice rat in profile walking across wire mesh, white feet and long tail visible

The northeastern marsh rice rat is a wetland rodent that swims through flooded grass. It occurs across eastern and southern wetlands. Its habits explain more than a map point: It eats seeds, plants, insects, and small aquatic animals. The records shown here document encounters and survey effort, not population size. Together, they show where this mammal has been found and why healthy habitat matters for its future.

Range through the year

Where Northeastern Marsh Rice Rat is seen

Northeastern Marsh Rice Rat is recorded in 8 US states from 1,265 occurrence records, most heavily in Florida (859 records) and Georgia (125).

Current range1,265 records · 8 states

Occurrence data by state and month

Northeastern Marsh Rice Rat – occurrence records by US state and month (1,265 total across 8 states)
State	Jan	Feb	Mar	Apr	May	Jun	Jul	Aug	Sep	Oct	Nov	Dec	Year
Florida	54	82	247	104	40	17	59	68	33	33	54	68	859
Georgia	7	22	·	5	1	17	6	3	1	15	36	12	125
Maryland	·	3	1	1	2	·	·	1	55	2	·	4	69
Alabama	8	1	8	2	·	10	3	14	5	2	3	·	56
South Carolina	7	3	3	2	3	4	·	2	·	1	12	8	45
Virginia	3	2	3	·	1	·	·	1	22	1	1	6	40
North Carolina	6	2	5	2	3	3	·	4	1	2	3	8	39
Delaware	2	·	3	2	·	·	·	·	·	5	20	·	32

Based on 1,378 georeferenced US records. Shading is observation density (where people record sightings), not true abundance. Alaska, Hawaii & Puerto Rico shown as insets.

Explore by state

Northeastern Marsh Rice Rat across 8 states

Occurrence records, conservation status, and the places it turns up, state by state. Open a state for detail, or visit its full page.

FloridaNativeOccasional960 records
State rankSecure
Notable placesEverglades National Park · Big Cypress National Preserve · Picayune Strand State Forest · Paynes Prairie Preserve State Park
Countiesrecorded in 12
Year-round in Florida, with recorded sightings peaking in March.
Full Florida page →All Florida mammals →
GeorgiaNativeOccasional134 records
State rankSecure
Notable placesOkefenokee National Wildlife Refuge.Wilderness Area · Fort Yargo State Park · Sapelo Island Wildlife Management Area
Countiesrecorded in 12
Year-round in Georgia, with recorded sightings peaking in November, with a smaller rise in February.
Full Georgia page →All Georgia mammals →
MarylandNativeCommon72 records
State rankApparently Secure
Countiesrecorded in 5
Year-round in Maryland, with recorded sightings peaking in September.
Full Maryland page →All Maryland mammals →
AlabamaNativeRare56 records
State rankSecure
Notable placesNatchez Trace Parkway · Horseshoe Bend National Military Park
Countiesrecorded in 12
Year-round in Alabama, with recorded sightings peaking in August, with a smaller rise in June.
Full Alabama page →All Alabama mammals →
South CarolinaNativeOccasional45 records
State rankSecure
Notable placesCape Romain National Wildlife Refuge.Wilderness Area · Francis Marion National Forest · Congaree National Park
Countiesrecorded in 11
Year-round in South Carolina, with recorded sightings peaking in November–December.
Full South Carolina page →All South Carolina mammals →
VirginiaNativeRare40 records
State rankSecure
Notable placesTidal Lands · Hog Island Wildlife Management Area
Countiesrecorded in 9
Year-round in Virginia, with recorded sightings peaking in September.
Full Virginia page →All Virginia mammals →
North CarolinaNativeRare39 records
State rankSecure
Notable placesBald Head Island State Natural Area
Countiesrecorded in 11
Year-round in North Carolina, with recorded sightings peaking in December–January, with a smaller rise in March.
Full North Carolina page →All North Carolina mammals →
DelawareNativeCommon32 records
State rankVulnerable
Countiesrecorded in 3
Year-round in Delaware, with recorded sightings peaking in November.
Full Delaware page →All Delaware mammals →

IUCN Red List status

LC – Least Concern

Widespread and abundant; not at risk.

Elevation

From 200 georeferenced records, the Northeastern Marsh Rice Rat is recorded from sea levelsea level to 273 m896 ft, with half of sightings below 10 m33 ft.

250–300 m820–984 ft

200–250 m656–820 ft

150–200 m492–656 ft

100–150 m328–492 ft

50–100 m164–328 ft

0–50 m0–164 ft

Each band shows the share of georeferenced sightings that fall within it. Records cluster where people live and hike, so low, populated elevations are over-represented. Read this as observation density, not true abundance.

Best encounter

Where and when to see a Northeastern Marsh Rice Rat

Your best chance: Florida.

Where: FloridaFL

Trophic relationshipsFood web What a Northeastern Marsh Rice Rat eats, and what eats it.

Eaten by2

Timber RattlesnakeCrotalus horridusRed CornsnakePantherophis guttatus

This speciesNortheastern Marsh Rice Rat

insectsEastern Lubber GrasshopperRomalea micropteraMarsh WrenCistothorus palustrisSeaside SparrowAmmospiza maritima

Eats4

A sample of documented feeding relationships, filtered to species that also occur in the US. Diet and predators vary by region and season, and this is not a complete list, many animals eat, and are eaten by, more than what has been formally recorded here.

Life history

The Northeastern Marsh Rice Rat (50 g1.8 oz) is an omnivore that first breeds around 0.1 years, carries a 25-day gestation, and bears about 3.9 young per litter. Maximum recorded longevity is 2.4 years.

Life cycle

Gestation25 days
Birthlitter of 3.9 young
Sexual maturity0.1 yr (female)
Typical lifespan2.4 years
Maximum recorded longevity2.4 years

Reproduction

Gestation: 25days
Litter size: 3.9youngaverage
Litters / year: 5.5litters
Age at first breeding: 0.1years

Diet composition

Omnivore

By foraging composition: 40% plant material, 20% seeds & grain, 20% fruit, 20% invertebrates.

40%

20%

Plant material40%
Seeds & grain20%
Fruit20%
Invertebrates20%

Most active around the clock.

Typical values for the species, not local measurements. Maximum longevity is the longest lifespan on record; most individuals live far less.

Commonly confused with

Animals people sometimes mistake for the northeastern marsh rice rat, and how to tell them apart.

Photo:Laura MaeiNaturalist (CC BY 4.0)

Hispid cotton rat

Sigmodon hispidus

How to tell apart Hispid cotton rat has coarse, bristly grizzled brown fur and a tail clearly shorter than its head and body, while the marsh rice rat has softer grayish fur, white feet, and a tail about as long as its body for swimming through flooded grass.

View species page Compare side by side

Life in its habitat

It eats seeds, plants, insects, and small aquatic animals. It’s tied to places supplying food and shelter. That connection explains much of its range.

What records reveal

Records follow surveyed marshes and can’t measure numbers between points. Survey effort varies, and accessible places receive more attention. A gap can’t prove absence.

Looking ahead

Wetland drainage and rising seas remove cover. Conservation works best when it protects connected habitat and reduces avoidable deaths. Surveys can reveal change without confusing records with animal numbers.

Sources

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
PhyloPicCC0 / CC-BY per itemthe to-scale silhouettesAndrew A. Farke (human silhouette, CC-BY 3.0)
AnAge (HAGR)CC-BY 3.0longevity, maturity, and gestation figures
IUCN Red Listattributed factthe global conservation status
Global Biotic Interactions (GloBI)CC0 · public domainthe food web
Amniote Life-History DatabaseCC0 · public domainreproduction figures
EltonTraitsCC0 · public domaindiet and foraging-activity data