Perhaps it is the ‘Harvest’ in Harvest Mouse that provides an instant association with summer – think ripe, swaying cereal fields and the picture starts to build but please allow me to expand the view.

Meet the Harvest Mouse

Weighing just 6g when fully grown (about the same as a 2 pence piece!), the Harvest Mouse is the smallest rodent in Britain. Well adapted to life in the “stalk-zone”, they are our only mammal species with a prehensile (capable of grasping) tail, which they use as an extra limb to grip hold of stems when climbing amongst tall vegetation such as grasses and sedges. They are russet-brown in colour with a fully white underside, and, unlike our other mouse species, they have short muzzles and small hairy ears. They are particularly elusive though, so you would have to be very lucky to spot one!

Habitat

Harvest Mice were historically described as abundant in cereal fields, but nowadays they tend to favour wilder habitats, including rough grasslands, marshes, and reedbeds. Within Hertfordshire, reedbed habitat is rare covering only about 20 hectares. This is an increase from just 12 hectares in the early 2000 as a result of dedicated work by many across the region. This will have benefitted Harvest Mice, as they require undisturbed areas of tall and dense vegetation in which they can forage and build their nests. One of the largest reedbeds in Hertfordshire and positioned along the River Lea which connects it to neighbouring habitats, Stanborough Reedmarsh Nature Reserve, which is managed by the Trust, is a perfect home for the species. By managing this habitat rotationally outside of the breeding season, we are able to maintain the reedbed whilst minimizing disturbance. 

Status 

Not much is known about the current status of Harvest Mice in the country, as they are incredibly under-surveyed, but they are believed to be in decline; in 2020, they were assessed to be Near Threatened in Great Britain on the Red List for British Mammals [1]. In addition to the loss and fragmentation of our wilder habitats, it’s believed that this decline is due in part to the modernisation of farming practices, which have reduced the habitat suitability of arable fields for Harvest Mice. Another cause for concern is their susceptibility to extreme weather conditions such as cold spells and floods, which are becoming more and more frequent as climate change progresses…

Nests

Harvest Mice make their tennis ball-sized nests by weaving together strips of long vegetation which are still attached to the surrounding plants, suspending them above the ground. They are the only small mammal in Britain to nest in the stalk-zone of tall vegetation in this way, making their nests a unique field sign to look out for in the winter months, once the vegetation has died back and the breeding season has ended. 

Find out more 

Did you know you can use our Wildlife Explorer webpages to find out more about some of our lesser-known native mammal species? Just head here!

References

[1] Mathews F, and Harrower C. (2020). IUCN – compliant Red List for Britain’s Terrestrial Mammals. Assessment by the Mammal Society under contract to Natural England, Natural Resources Wales and Scottish Natural Heritage. Natural England, Peterborough ISBN 978-1-78354-485-1 (https://www.mammal.org.uk/science-research/red-list/)