Rice field rat
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Rice field rat ( Rattus argentiventer ) |
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| Rattus argentiventer | ||||||||||||
| ( Robinson & Kloss , 1916) |
Rice field rats ( Rattus argentiventer , Syn . : Rattus rattus argentiventer , Rattus rattus brevicaudatus , Rattus rattus bali , Rattus rattus umbrivente ) are medium-sized rats in Southeast Asia that have adapted their way of life to the cultivation of rice fields. They live directly in or on rice fields and can lead to a harvest loss of up to 60% if they are eaten. In many areas of Southeast Asia, they are considered the largest agricultural pest among rodents .
Appearance
Rice field rats with a weight of up to 239 g and a head-trunk length of up to 230 mm belong to the medium-sized rats. Their dark colored tail is always slightly shorter than the head-torso with up to 210 mm. The somewhat wiry fur on the back of the rice field rats is colored orange-brown and usually has black spots. The color of the fur on the belly side can vary from silvery white to gray, and a dark stripe runs lengthways along the middle of the belly. Rice field rats have a moderately long snout and large, slightly hairy ears. There is usually an orange-colored area of fur directly in front of the ears. The top of the thin, long feet is also covered with some dark hair.
distribution
The occurrence of the rice field rats extends over the lowlands of southern Thailand , Cambodia and Vietnam as well as along the Mekong to southern Laos . They can also be found on the Malay Peninsula and the main islands of Indonesia . Isolated populations are found in southern New Guinea and islands in the Philippines - Cebu , Luzon , Mindanao , Mindoro and Negros . The deposits on Sulawesi , the Lesser Sunda Islands , the Philippines and New Guinea are believed to have been introduced by humans.
Habitat
Rice field rats prefer habitats that are regularly flooded by water. They are found in rice fields, gardens and plantations where they dig their burrows. These are only ever inhabited by a single animal and its offspring. They can only be found in localities during migrations. Their choice of habitat is closely adapted to agricultural activities. Outside of rice cultivation, most of the buildings are on canals and in gardens; when the fields are planted, more and more buildings are being built in the dams of the rice fields.
food
The food spectrum of rice field rats includes grasses, which also include rice , (rice field) herbs, cereals and other seeds as well as invertebrates ( crustaceans , snails and insects ).
reproduction
The reproductive cycle of rice field rats is closely related to agricultural activities of humans. The first pairing of a season takes place shortly before the rice fields are planted, so that the first young animals are born while the rice plants are growing. There may be a second litter when the rice ripens and a third after the rice harvest. If the rice fields are continually planted, the young of the first litter can reproduce within the same year.
Theoretically, the first mating in females is possible at an age of around 28 days (31–40 g), but it usually takes place later, when they weigh 60 to 120 g. Males are sexually mature at around 59 days (90 g) of age. The females are pregnant for an average of 21 days (20–26 days). While the number of young animals in a litter can be up to 18, the mean is significantly lower. This varies between the different regions and is usually from 5–7 pups in Malaysia to 10–11 pups in West Java . In captivity there are 7–8 animals in a litter.
While with most rodents a new litter causes the young of the previous litter to leave the nest, with rice field rats several generations can live within a burrow. This, and the fact that up to 100% of all females in a population can be pregnant, can be the reason for the sometimes extremely high population densities. In Indonesia, for example, 500–600 individuals per hectare were counted (with double rice planting); higher densities may well be possible.
Rice field rats as pests and a source of food
Rice paddy rats can cause a 10–25% crop loss, with the greater damage being the second growth. If there are three "rice generations" or "places of refuge" (main canals, "mountainous" rice fields), 30–50% of the harvest can be lost. In rural Thailand , particularly in the Pathum Thani Province , the rat meat of these rodents is eaten.
swell
- Ken P. Aplin, Peter R. Brown, Jens Jacob, Charles J. Krebs, Grant R. Singleton: Field methods for rodent studies in Asia and the Indo-Pacific (= ACIAR monograph 100). Australian center for international agricultural research, Canberra 2003, ISBN 1-86320-393-1 , online (PDF; 3.13 MB) .
Web links
- Rattus argentiventer inthe IUCN Red List of Threatened Species 2013.2. Posted by: Ruedas, L., Aplin, K. & Lunde, D., 2008. Retrieved December 6, 2013.