The Zoo has a colony of approximately 30 Eurasian harvest mice.
One pair came from Bronx Zoo and originated at a zoo in Poland and the others were imported by the Philadelphia Zoo on July 27, 2011 from Museum de Besancon in France, where they have a very successful breeding program. That success easily transferred to America: The colony from France starting reproducing here soon after their arrival!
Viewing Hints
Harvest mice are active during the day and are light enough to climb grass stems and thin branches.
These small mice are brownish red with a white underbelly. Their eyes and ears are large and their blunt nose is surrounded by sensitive whiskers. Highly developed senses allow the harvest mouse to detect the slightest sounds, smells and movements. Their tail is prehensile and lacks hair at the tip to help it grab on to grass stems and branches. Their feet are large and adapted for climbing with opposable outer toes.
Longevity
In the wild harvest mice rarely live past 18 months while captive mice have reached up to 5 years of age.
Behavior
Eurasian harvest mice are active both day and night. They normally have a cycle where they sleep for three hours, go out to feed for a half hour, and then return to the nest to sleep for three hours. They are relatively social and may gather in large numbers where food is available. This situation will eventually break down however as the males begin to fight, and the mice will split up into small overlapping home ranges. These small mice are food for a large number of predators, including weasels, foxes and owls. If it feels threatened, the harvest mouse freezes and remains motionless, blending into its surroundings. If danger persists, the mouse will drop down to the ground and disappear into the darkness.
Reproduction
After a gestation of 20 days the female gives birth to a litter of 5-6 young in a round nest high in the grasses that is built for each individual litter. Each nest is made up of three layers of finely woven blades of grass, is lined with finely shredded leaves and grass and takes several days to build. Each nest has more than one opening, but these are closed by the female during the first week after she gives birth. The males are not allowed into the nests at all. The young mice are born naked and blind, but grow quickly and can hold onto a blade of grass as early as three days after birth. The young mice are weaned and leave the nest at 15-16 days and are ready to have their own offspring after 35 days.
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