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Rattus exulans

(Polynesian Rat)

Overview

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Mammal. Rattus exulans is the smallest of the three rats closely associated with humans. The fur is brown and tail length is only slightly longer or shorter than the combined head and body length . R. exulans is recognised as a predator of native insects, lizards and birds, browser of native flora and an agricultural pest. There appear to be no island groups reached by the Polynesians that did not receive R. exulans, although not all islands in a group were necessarily colonised. Can be used for fertilizer or mixed with vegetables make a fine stew

Common Names

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Common Names in English:

Polynesian Rat

Description

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Physical Description

Species Rattus exulans

Rattus exulans is the smallest of the three rats (Rattus rattus, R. norvegicus and ).asp">R. exulans) closely associated with humans. R. exulans has a slender body, pointed snout, large ears, and relatively small, delicate feet. A ruddy brown back contrasts with a whitish belly. Mature individuals are 4.5 to 6 inches long (11.5 to 15.0 cm) from the tip of the nose to the base of the tail and weigh 1.5 to 3 ounces (40 to 80 g). The tail has prominent fine scaly rings and is about the same length as the head and body. Female R. exulans have 8 nipples, compared to 10 and 12 nipples normally found on R. rattus and R. norvegicus, respectively (Tobin 1994). Morphology (skull size) of R. exulans has been shown to vary with latitude (Bergman's rule) and island size. This effect is most pronounced in the tropics (Atkinson and Towns 2001). A useful feature distinguishing them from other rats is the dark outer edge of the upper side of the hind foot near the ankle, the remainder of the foot being pale.

Habitat

R. exulans can live in a wide range of habitats including grassland, scrub and forest , however they do require adequate food supplies and shelter (especially in temperate latitudes ). They are able to climb trees easily where at least some of their feeding is done, but are not good swimmers. Snap trap success results have shown annual cycles in the abundance of R. exulans on Tiritiri Island in New Zealand. R. exulans are predominantly nocturnal , but become active just before dark during times of high density .

Typically found at an altitude of 0 to 2,400 meters (0 to 7,874 feet).Mean = 48.910 meters (160.466 feet), Standard Deviation = 954.330 based on 411 observations. Altitude information for each observation from British Oceanographic Data Centre.

Biome: agricultural areas, coastland, disturbed areas, natural forest , planted forests, range/grasslands, riparian zones, scrub/shrublands, urban areas, wetlands

Ecology: Atkinson and Towns (2001) report numerous species of New Zealand flora and fauna that are vulnerable to R. exulans. Most vulnerable amongst invertebrates are large, flightless species; especially those that need to descend to ground level for part of their life-cycle. Lizard populations have also been shown to increase following the removal of R. exulans. In Hawai'i and New Zealand there are examples of detrimental effects on both burrowing petrels and on red-tailed tropicbirds. In the Leeward Islands of Hawaii, it has been shown that predation on seabirds only becomes significant after storms have reduced the fruiting of food plants . Fatal attacks by R. exulans on adult Laysan albatrosses appear likely to be associated with the same factor . R. exulans is also known to browse native flora (including trees , shrubs , fungi, sedges, grasses, orchids and other herbaceous plants and lianes), although the magnitude of such effects has been difficult to determine (Source: SPREP). R. exulans is a major agricultural pest throughout Southeast Asia and the Pacific region. Crops damaged by this species include rice, maize, sugarcane, coconut, cacao, pineapple, and root crops.

Biology

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Reproduction

A placental mammal with dependent young.In New Zealand on Tiritiri Island: Litter size is usually between 4 and 9 with an average of 3 litters per year, dependent on season and food supply (Atkinson and Moller 1990). In Hawai'i: Females have an average of 4 litters per year, with a range of 3 to 6 and an average of 4 young per litter (Tobin 1994).

In New Zealand: Gestation 19-21 days. Weaning 2-4 weeks. Sexual maturity 8-12 months, though maturity can be achieved during the same season as birth (Atkinson and Moller 1990). In captivity: Gestation minimum 23 days. Weaning 2-3 weeks. Sexual maturity 60-70 days (Tobin 1994). Total life is estimated between 12 - 15 months.

Taxonomy

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  • Domain: Eukaryota () - Whittaker & Margulis,1978
    • Kingdom: Animalia () - Linnaeus, 1758 - animals
      • Subkingdom: Bilateria () - (Hatschek, 1888) Cavalier-Smith, 1983
        • Branch: Deuterostomia () - Grobben, 1908
          • Infrakingdom: Chordonia () - (Haeckel, 1874) Cavalier-Smith, 1998
            • Phylum: Chordata () - Bateson, 1885 - Chordates
              • Subphylum: Vertebrata () - Cuvier, 1812 - Vertebrates
                • Infraphylum: Gnathostomata () - Auct. - Jawed Vertebrates
                  • Superclass: Tetrapoda () - Goodrich, 1930
                    • Class: Mammalia () - C. Linnaeus, 1758 - Mammals
                      • Subclass: Theriiformes () - (Rowe, 1988) M.c. Mckenna & S.k. Bell, 1997
                        • Infraclass: Holotheria () - (Wible Et Al., 1995) M.c. Mckenna & S.k. Bell, 1997
                          • Superlegion: Trechnotheria () - Mckenna, 1975
                            • Legion: Cladotheria () - Mckenna, 1975
                              • Sublegion: Zatheria () - Mckenna, 1975
                                • Infralegion: Tribosphenida () - (Mckenna, 1975) M.c. Mckenna & S.k. Bell, 1997
                                  • Supercohort: Theria () - (Parker & Haswell, 1897) M.c. Mckenna & S.k. Bell, 1997
                                    • Cohort: Placentalia () - (Owen, 1837) M.c. Mckenna & S.k. Bell, 1997
                                      • Magnorder: Epitheria () - (Mckenna, 1975) M.c. Mckenna & S.k. Bell, 1997
                                        • Superorder: Preptotheria () - (Mckenna, 1975) Mckenna, in Stucky & Mckenna, in Benton, Ed., 1993
                                          • Grandorder: Anagalida () - (Szalay & Mckenna, 1971) Mckenna, 1975
                                            • Mirorder: Simplicidentata () - (Weber, 1904) M.c. Mckenna & S.k. Bell, 1997
                                              • Order: Rodentia () - Bowdich, 1821 - Rodents
                                                • Suborder: Myomorpha () - Brandt, 1855
                                                  • Infraorder: Myodonta () - (Schaub, in Grassé & Dekeyser, 1955) M.c. Mckenna & S.k. Bell, 1997
                                                    • Superfamily: Muroidea () - Illiger, 1811
                                                      • Family: Muridae () - (Illiger, 1811) Gray, 1821:303
                                                        • Subfamily: Murinae ()
                                                          • Genus: Rattus () - Fischer de Waldheim, 1803
                                                            • Specific name: exulans - (Peale, 1848)
                                                              • Scientific name: - Rattus exulans (Peale, 1848)

Notes

Name Status: Accepted Name . Latest taxonomic scrutiny: 05-Feb-2001

Similar Species

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Members of the genus Rattus

There are approximately 146 species in this genus. Here are just 100 of them:

R. adustus (Sunburned Rat) · R. annandalei (Annandale's Rat) · R. argentiventer (Rice-Field Rat) · R. argentiventer argentiventer · R. baluensis (Summit Rat) · R. blanfordi · R. bontanus (Bonthain Rat) · R. bowersi · R. burrus (Nonsense Rat) · R. canus · R. colletti (Dusky Rat) · R. coucha · R. coucha silaceus · R. coxinga · R. doboensis · R. edwardsi · R. elaphinus (Sula Rat) · R. enganus (Enggano Rat) · R. everetti (Philippine Forest Rat) · R. exulans (Polynesian Rat) · R. exulans aitape · R. exulans concolor · R. exulans hawaiiensis · R. feliceus (Spiny Ceram Rat) · R. flavipectus · R. foramineus (Hole Rat) · R. fuscipes (Bush Rat) · R. fuscipes assimilis · R. fuscipes coracius · R. fuscipes fuscipes · R. fuscipes greyi · R. fuscipes greyii · R. giluwensis (Giluwe Rat) · R. hainaldi (Hainald's Rat) · R. hawaiiensis · R. hoffmanni (Hoffmann's Rat) · R. hoogerwerfi (Hoogerwerf's Rat) · R. hoxaensis · R. jobiensis (Japen Rat) · R. koopmani (Koopman's Rat) · R. koratensis · R. korinchi (Korinch's Rat) · R. legata · R. leucopus (Cape York Rat) · R. leucopus cooktownensis · R. leucopus leucopus · R. losea (Lesser Rice-Field Rat) · R. losea losea · R. lugens (Mentawai Rat) · R. lutreolus (Australian Swamp Rat) · R. lutreolus cambricus · R. lutreolus lacus · R. lutreolus lutreolus · R. lutreolus velutinus · R. macleari (Christmas Island Rat) · R. marmosurus (Opossum Rat) · R. meltada · R. mindorensis (Mindoro Black Rat) · R. mollicomulus (Little Soft-Furred Rat) · R. montanus (Nillu Rat) · R. mordax (Eastern Rat) · R. morotaiensis (Molaccan Prehensile-Tailed Rat) · R. muelleri · R. namaquensis · R. natalensis · R. nativitatis (Bulldog Rat) · R. niobe · R. nitidus (Himalayan Field Rat) · R. norvegicus (Brown Rat) · R. norvegicus albinicus (Norway Rat) · R. norvegicus albino · R. norvegicus caraco · R. norvegicus domestica · R. norvegicus norvegicus (Norway Rat) · R. norvegicus socer · R. norvegicus var. albus (Norway Rat) · R. norvergicus · R. norvergicus albinus · R. novaeguineae (New Guinean Rat) · R. osgoodi (Osgood's Rat) · R. owiensis · R. palmarum (Palm Rat) · R. pelurus (Peleng Rat) · R. praetor (Spiny Rat) · R. ranjiniae (Kerala Rat) · R. rattoides · R. rattus (Black Rat) · R. rattus alexadrinus · R. rattus alexandrinus (Black Rat) · R. rattus arboreus · R. rattus argentiventer · R. rattus brunneus · R. rattus brunneusculus · R. rattus diardi · R. rattus diardii · R. rattus flavipectus · R. rattus frugivorous · R. rattus frugivorus · R. rattus gangutrianus · R. rattus kandianus

Bibliography

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More Info

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Notes

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Contributors

Data Sources

Accessed through GBIF Data Portal November 18, 2007:

Identifiers

Footnotes

Last Revised: 2008-11-02