Old World Harvest Mouse (Micromys minutus)


Class: Mammalia
Order: Rodentia
Family:    Muridae
Size:    Length: 2 to 3 inches (5 to 7.6 cm) 
Weight: 0.18 to 0.35 ounce (5 to 10 g)
Diet: Grain, insects, fruit, seeds and grass
Distribution: Europe and northern Asia
Young:  4 to 9 young, up to 3 times per year
Animal Predators:  Hawks, owls, snakes, weasels, foxes, stoats, crows and cats
IUCN Status: Lower Risk, Near Threatened
Terms: No special terms
Lifespan: 1 to 2 years in the wild and up to 5 years in captivity



·        Harvest mice love to bask in the sun during cool weather.

·        The minimum time between litters is 17 to 18 days.

·        Their scientific name Micromys minutus means the smallest tiny mouse in Latin.



These tiny animals are among the smallest of the world’s mammals. They have large eyes; large, round ears; and a small, blunt nose. Their back and head is covered with thick, soft, red-brown fur, while their underbelly is white. There are five toes on each of their hind feet and four on each front foot. They are the only European mammals to have a prehensile tail, which means they can hold or grip things with their tail.  



Old world harvest mice are found in Europe and parts of northern Asia, including Korea, Japan and China. They prefer habitats with tall grass, often near ponds, rivers or lakes. They live in fields and build nests on the stems of tall grass during the summer. During the winter, they live underground or in old buildings, but they do not hibernate.  


Feeding Habits

They often feed on the grain grown in fields, but also on potentially destructive insects, so they are both a blessing and a curse to farmers. Harvest mice also eat fruit, seeds and grass. They have a special digestive system that compels them to re-ingest pre-digested food after defecation. This allows them to get the most possible nutrients out of their food. 



Mating takes place anytime from spring to early autumn. The female undergoes a 17 to 21 day pregnancy and gives birth inside her cozy, deep nest made of woven grass and lined with shredded leaves, on a stalk three to four feet above the ground. She makes a new nest for each litter. The male is not allowed in the nest and has nothing to do with rearing the offspring. The youngsters are born naked with their eyes closed. Their eyes open approximately a week after birth and they begin to be weaned at 11 days. They develop quickly and leave the nest for good when they are 15 to 16 days old. 



Although hundreds of these mice can be found in a relatively small area, they merely tolerate each other and are not particularly social. Harvest mice have excellent hearing and when they realize a predator is near, they will freeze; if that does not work, they try to find a place to hide, such as an underground burrow. Harvest mice are active both during the day and night; however, they follow a three-hour rhythm of sleeping and feeding: they sleep for three hours, then feed for a half hour, then sleep again for three hours and so on. 



Because of diminishing habitat due to human settlement, old world harvest mice have been forced to live near human dwellings, including in grain fields, but they are left homeless when farmers clear their land during harvest season. The farm equipment kills youngsters still in the nest, and many adults also die because they need tall grass to survive. When it is cut, they are left in the open in clear view of predators. Although not yet considered endangered, their numbers have been greatly reduced. 










Old World Harvest Mouse Wildlife Fact File, IM Pub, US