Louisiana mammals

Northwestern Marsh Rice Rat in Louisiana

Oryzomys texensis

Native to Louisiana S5 Secure in Louisiana

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

IUCN Red List status

NE – Not Evaluated

Not yet assessed against IUCN Red List criteria.

Northwestern marsh rice rat on a bare soil bank, unrestrainedAI-generated image: Northwestern marsh rice rat foraging among sedges at dusk. No additional license-safe photograph of this species exists. This image was generated with AI from verified reference material and reviewed by our editorial team for accuracyAI-generated image: Northwestern marsh rice rat grooming on a muddy bank. No additional license-safe photograph of this species exists. This image was generated with AI from verified reference material and reviewed by our editorial team for accuracy
Photo: Rich Sommer · CC BY 4.0Northwestern marsh rice rat on a bare soil bank, unrestrainedAI-generated image No additional license-safe photograph of this species exists. This image was generated with AI from verified reference material and reviewed by our editorial team for accuracyNorthwestern marsh rice rat foraging among sedges at duskAI-generated image No additional license-safe photograph of this species exists. This image was generated with AI from verified reference material and reviewed by our editorial team for accuracyNorthwestern marsh rice rat grooming on a muddy bank

Northwestern Marsh Rice Rat in Louisiana, by the numbers

Rare in Louisiana 52nd most recorded of 72 mammals logged in Louisiana

23 occurrence records
9 with iNaturalist photos
Oct 30, 2022 Last seen in Louisiana

Records from 2000–2026.

23 total records count every Louisiana occurrence from GBIF and iNaturalist; the monthly chart covers the 22 records with a full observation date.

When to look for the Northwestern Marsh Rice Rat in Louisiana

Most sightings fall in December to January.

22 Louisiana occurrence records (iNaturalist and GBIF) by month of year, 2000–2026. Shows when the species is recorded, not a guarantee of presence. Based on a small number of dated records; the seasonal pattern may not be representative.

Monthly Louisiana records (table)
MonthRecords
January5
February1
March4
April0
May0
June4
July0
August0
September0
October3
November0
December5

Monthly northwestern marsh rice rat occurrence records (iNaturalist and GBIF) in Louisiana, 2000–2026.

Seasonality

Year-round in Louisiana, with recorded sightings peaking in December–January, with a smaller rise in March and June.

Occurrence map

Where Northwestern Marsh Rice Rat has been recorded in Louisiana

23 records mapped · zoom and drag to explore

23 Louisiana records mapped

Notable places to look

Park, forest, or monumentiNaturalist records
Grand Isle 2

Protected places with the most northwestern marsh rice rat 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 Louisiana

CountyRecords
East Baton Rouge County 6
Terrebonne County 4
Jefferson Davis County 2
Lafourche County 2
Natchitoches County 2
Orleans County 2
Vermilion County 1
Plaquemines County 1
Tangipahoa County 1
Lafayette County 1
Other localities 1

The complete county distribution, spread across 10 Louisiana counties. Every occurrence record falls in one county, so these sum to the total. Counties from GBIF and US Census boundaries.

Northwestern marsh rice rats carry a NatureServe S5 secure rank in Louisiana despite a global rank that’s still unresolved, GNR, reflecting recent taxonomic splitting of the marsh rice rat complex. The record leans toward GBIF (20 of 23 records), and Grand Isle’s 2 logged sightings anchor the coastal marsh habitat this semi-aquatic rodent depends on.

Records bookend the year, January and December each carry 5 of the 23 sightings, together nearly half the total, with long stretches of complete silence from March through May and July through September, a pattern that may track cooler-season trapping timing more than any true seasonal shift in this marsh-dwelling rat’s activity.

Occurrence data from iNaturalist.

Northwestern marsh rice rat on a bare soil bank, unrestrained
Full species profile Northwestern Marsh Rice Rat Oryzomys texensis Size 22.6–30.5 cm8.9–12 in Weight 40–80 g1.4–2.8 oz View the full profile

More mammals in Louisiana 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
  • USGS Protected Areas Databasepublic domainthe named parks, forests, and refuges behind "notable places to look"