Description

Other Taxonomic Groupings - Named subspecies (e.g. Bailey 1946) are probably only color morphs (Taylor 1990).

Taxonomy

Kingdom	Phylum	Class	Order	Family	Genus
Animalia	Chordata	Mammalia	Rodentia	Muridae	Rattus

Synonyms

Mus rattus; Epimys rattus

Invasion History

Chesapeake Bay Status

First Record	Population	Range	Introduction	Residency	Source Region	Native Region	Vectors
1609	Extinct	Contracting	Introduced	Boundary Resident	Europe	East Asia	Shipping(unspecified)

History of Spread

Rattus rattus (Black Rat) is probably native to southeast Asia or India, but its range probably expanded greatly with the development of agriculture and concentrated human settlements (Lever 1985; Taylor 1990). It was introduced to Europe in Roman times (Taylor 1990), and to North America in the early 1600's (Lever 1985) or earlier, and probably spread rapidly on ships and overland modes of transport. However, in northern areas, it was rapidly displaced by the larger and more aggressive R. norvegicus (Norway Rat), but persisted in the tropics and southeastern United States (Hall and Kelson 1959; Paradiso 1969; Walker 1968). Rattus rattus is the 'common rat on ships, to which it gains access by climbing the moorings', and can be expected to be periodically reintroduced by ships (Paradiso 1969). Unlike R. norvegicus, R. rattus rarely enter water, but they are much better climbers than the larger species (Taylor 1990). Although Rattus rattus are not very aquatic, they tend to occur in urban waterfront areas (Paradiso 1969; Taylor 1990), and in tropical and warm-temperate parts of the world can be an important intertidal predator (Zamorano 1986). Rattus rattus are cosmopolitan, but as noted above, are most abundant and widespread in the tropics (Taylor 1990).

The earliest mention of Rattus rattus in North america may be from the Chesapeake Bay, that of John Smith at Jamestown VA in 1612 (cited by Lever 1985):' In searching our casked corne, we found it halfe rotten; the rest so consumed with the many thousand rattes (increased first from the ships) that wee knew not how to keep the little wee had.' Rattus rattus were apparently rare by the late 1800's, and were not mentioned in an unpublished manuscript (1895) on mammals of MD by W. H. Fisher (Lee 1988). Specimens were collected in dock areas of Washington D.C. in 1912 and 1923, and a few were found in waterfront buildings in Baltimore in 1949 (Paradiso 1969). An isolated population was found in a barn in western MD (Garrett County) in 1980 (Feldhamer and Gates 1980). In VA, R. rattus was probably present throughout the state before the coming of R. norvegicus, but in the 20th century, was only known from three counties in the southeast (Nansemond; Dinwiddie; Brunswick), in the vicinity of the Dismal Swamp (Bailey 1946; Handley and Patton 1947).

History References - Bailey 1946; Feldhamer and Gates 1980; Handley and Patton 1947; Lee 1988; Lever 1985; Paradiso 1969; Taylor 1990; Zamorano 1986

Invasion Comments

Population Status- There are no recent records of R. rattus. It is considered extinct around Chesapeake Bay, but is likely to be occasionally re-introduced by ships (Paradiso 1968).

Ecology

Environmental Tolerances

	For Survival		For Reproduction
	Minimum	Maximum	Minimum	Maximum
Temperature (ºC)
Salinity (‰)	35.0	0.0	0.0
Oxygen
pH
	Salinity Range	fresh-eu

Age and Growth

	Male	Female
Minimum Adult Size (mm)
Typical Adult Size (mm)
Maximum Adult Size (mm)
Maximum Longevity (yrs)
Typical Longevity (yrs

Reproduction

	Start	Peak	End
Reproductive Season
Typical Number of Young Per Reproductive Event
Sexuality Mode(s)
Mode(s) of Asexual Reproduction
Fertilization Type(s)
More than One Reproduction Event per Year
Reproductive Startegy
Egg/Seed Form

Impacts

Economic Impacts in Chesapeake Bay

Rattus rattus (Black Rat) may have been the primary rat of colonial America before the coming of the R. norvegicus (Norway Rat), but in recent decades, it has occurred in and near the Chesapeake region only as relict populations in warehouses, barns, swamps, and an occasional arrival on ships (Bailey 1946; Paradiso 1969; Feldhamer and Gates 1980). At present, it has no economic impacts in the Chesapeake region.

References - Bailey 1946; Feldhamer and Gates 1980; Paradiso 1969

Economic Impacts Outside of Chesapeake Bay

Rattus Rattus (Black Rat) is now rare in most cooler temperate industrialized areas of Europe and North America, but may be abundant in the southeastern United States, and the Mediterranean, and the tropics, where it is a widespread pest and disease carrier. It is also the predominant rat on ships (Hall and Kelson 1959; Taylor 1990).

References - Hall and Kelson 1959; Taylor 1990

Ecological Impacts on Chesapeake Native Species

Rattus rattus (Black Rat) may have been the predominant rat in colonial America before the introduction of the Rattus norvegicus. Now, in the Chesapeake Bay region it appears to be either extinct or reduced to small relict populations in waterfront buildings (Paradiso 1969; Taylor 1990), rural barns (Feldhamer and Gates 1980), and possibly in the Dismal Swamp (VA) (Bailey 1946; Handley and Patton 1947). Although R. rattus is less aquatic than R. norvegicus, it may have once been locally important in wharf and harbor areas of the Chesapeake, and can be a significant intertidal predator in areas with milder climates, e.g. Chile, Oregon, South Africa (Zamorano 1986), and tropical islands (Taylor 1990).

References - Bailey 1946; Feldhamer and Gates 1980; Handley and Patton 1947; Paradiso 1969; Taylor 1990; Zamorano 1986

Ecological Impacts on Other Chesapeake Non-Native Species

Rattus rattus (Black Rat) seems to have been largely displaced by R. norvegicus (Norway Rat) in temperate areas, largely due the latter's greater tolerance of cold (Taylor 1990). Where the species co-occur, R. rattus is frequently found on the upper floors of buildings because of its greater climbing ability, which also makes it the predominant species on ships (Paradiso 1969).

References- Paradiso 1969; Taylor 1990

References

Bailey, John (1946) The Mammals of Virginia, In: (Eds.) . , Richmond, VA. Pp.

Feldhamer, George A.; Gates, J. Edward (1980) A black rat population in western Maryland, Proceedings of the Pennsylvania Academy of Science 54: 191-192

Hall, E. Raymond; Kelson, Keith R. (1959) The Mammals of North America, , New York. Pp.

Handley, Charles O, Jr.; Patton, Clyde P. (1947) Wild Mammals of Virginia, , Richmond VA. Pp.

Lee, David S. (1988) Wm. H. Fisher's 'Mammals of Maryland': a previously unknown compilation of the state's fauna, Maryland Naturalist 32: 9-37

Lever, Christopher (1985) Naturalized mammals of the world., In: (Eds.) . , London. Pp.

Paradiso, John L. (1969) Mammals of Maryland, , Washington, D.C.. Pp.

Taylor, K. D. (1990) Ship Rat: Rattus rattus., , Oxford. Pp. 255-259

Taylor, K. D.; Fenn, M. G.; MacDonald, D. W. (1990) Common Rat: Rattus norvegicus., , Oxford. Pp. 248-255

Walker, Ernest P. (1968) Mammals of the World, , Baltimore, MD. Pp.

Zamorano, Juan H. (1986) Rattus rattus, un depredador intermareal poco conocido., Medio Ambiente 8: 58-62