Small mammals on the night camera

David Beeson, late July 2021

My Apeman Wildlife camera has again been pointed at a peanut feeder just alongside our garage. This is adjacent to where I found two (rare) UK dormouse nests in November last year, and then recorded a pair on this feeder. Since that time brown rats found the feeder and started to dominate it – hence a new, highly protected feeder. Which is sad as I quite like rats, having kept two as pets, and the images on this feeder are less good. Yet yet rats dominated too much and had to be moved on.

Species – Bank Vole – The Mammal Society — I find bank (long-tailed) voles active in the day in both our meadows and climbing onto the feeder. Note the small eyes and rounded head. Short-tailed voles have noticeably shorter tails and have not been on the feeder, preferring grassland.

House Mouse and Wood Mouse | www.wildlifekate.co.uk — Wood mouse on left, house mouse to the right.

The UK has a limited range of small mammals – the voles (long and short-tailed, the mice (yellow-necked, long-tailed, dormice and house mice) and shrews (common and pygmy). Edible dormice (introduced) are found in an area north of London but not around here. We also have brown rats and a remnant population of black rats in a few locations. Regrettably, we have no harvest mice here, although they occur with a couple of miles.

Dormice are found in Southern England, East Wales and a few other scattered locations, where they are being enhanced or re-introduced. They are deciduous woodland specialists, especially where there is a well-developed shrub layer. Mature hedgerows are also occupied, and ours is a conifer hedge (our neighbours’) enhanced with a diverse range of deciduous shrubs on our side. Ancient woodlands are ideal, but some dormice have been found living in coniferous areas.

Rewilding: Hedge highways and restored woodlands aim to boost hazel dormouse populations in Yorkshire Dales | The Independent — Dormouse. Note especially the furry tail, large eyes and general body shape. On my feeder they seem to feed head down, while the other mice feed head up. Voles prefer to sit at base level.

I recently found a dead dormouse in a zone of pure oaks with no under layer, although a diverse range of plants was within 100m.

Dormice are almost exclusively nocturnal, and they can travel up to the tree canopy. Ours, so far, have been nocturnal and are content feeding from shelled walnuts, hamster food and peanuts. Droppings showed flowers were also being eaten. Our hedge has an array of food sources throughout the year: holly berries over winter through to ivy fruits in the autumn. There are climbing roses for hips, honeysuckle, cherry plums, damsons, apples, hawthorn berries and more. Dormice are poorly equipped to digest cellulose, so prefer softer vegetation and may avoid nuts.

Two dormouse nests. The larger is a breeding nest, the smaller non-breeding size. These were located under 1 m from the soil, in a small shrub of maximum height 1.5 m.

Litter size is said to be between 2 – 9. Typically 4 or 5. They usually breed the year after being born. Life span, in the wild, at least 4 years. It is said that crows and magpies drop dormice they have caught, and that could have been the origin of the one I discovered under pure oak.

Dormice have special UK protection and handling them without a license is an offence – not that it was when I first caught one!

During the day long-tailed (bank) voles dominate the feeder, at night it becomes the realm of the mice – long-tailed, yellow-necked and dormice.

I have been checking this feeder since April, yet the dormice only reappeared in early July. Perhaps they had been feeding elsewhere since ending their hibernation or were very late in emerging. To date I have seen no signs of nests.

A brown rat approaching the previous feeder. I have kept two ex-laboratory brown rats and found them to be highly intelligent and nimble. I do not make any attempt to remove them from the garden … the house is another matter! How do I know it is a rat? Larger size and thicker tail, which is scally.

Measurements.

In summer dormouse adults: head and body 80 – 85 mm plus tail, 57 – 68 mm. Weight up to 25 g in pregnant females.

So, here are wildlife camera images; I regret not to John’s standard.

Night one.

The long, non-furry tail says: long-tailed mice or yellow-necked mice. The latter are larger, less common, and have a yellow band across the underside of the neck. The tail length is less than the body length. If yellow-necked they would need to be young animals to be this size … so, I suggest these are long-tailed mice, also called wood mice. Let’s call them wood mice!

Wood mice range in size in summer: 80 – 100 mm plus tail, 70 – 95 mm. So considerably larger than the dormouse at maturity. Of course, young will be of various sizes. Yellow-necked have tails longer than their body, not so with the long-tailed mouse.

House mice are uniform grey, wood and yellow-necked brown in back colouration … not that I can see that on black-while images! House mice are largely creatures of urban environments as combine harvesters and ‘clean’ farming has decimated their food supplies in non-urban areas. Of 1536 small mice captured during a study in Wiltshire only 5 were house mice. The species is virtually never found in woodland areas. It may still occur in intensive poultry and pig units. One location that they do still occupy is off-shore islands. There, if other mice are not present, they may survive but they fail to cope with competition.

I have not seen house mice in this area, so, again the waiting mouse is a long-tailed. Inside the feeder, with the furry tail is a dormouse. The dormouse seems to be dominant as the wood mouse waited some time before it got onto the feeder.

A triplet. The dormouse had just arrived. Do note the tail length – each wire grid being one by one inch. I suggest the tail is: 2 inches. 50 mm. Suggesting sub-adult / young animal.

Comparing dormouse and, what appears to be, a yellow-necked mouse as the tail is as long as its body. (Take no notice of the temperature data, it is not accurate.)

Nice profile. Sorry, it will not allow more cropping. Here the mouse is 10 cm long, plus tail . Tail length suggest long-tailed (wood) mouse.

Dormouse is about 6 inches / 15 cm long – stretched out. 7 cm tail, 8 body. Mammals of Great Britain, THE mammal book, states adult size in summer is 80mm – 85mm and tail 57 – 68mm. So, an adult? The triplet dormouse had a tail of 50 mm, so smaller.

I have attempted to contrast the dormouse to see its size more clearly. Body length is about 3 inches, 75 – 80 mm. Tail, just over 2 inches, 55 mm. Adult size.

Head down feeding on the previous feeder – last November. The mouse is looking fat, ready for hibernation.

Night two

The camera has been moved higher to attempt to achieve more accurate size measurements.

Body length greater than tail length. Body 100 mm. Adult wood mouse.

Body length about 5 cm. Young wood mice.

Four mice. The one on the top: Which type of mouse? Adult or young? Answer A at end of article.

Above is a very young dormouse – 5 cm, hairy tail, more rounded ears.

Okay, who do we have here? Answer B at the end.

22.37. Tail longer than body, so probably a yellow-necked mouse.

A good general view of an adult wood mouse.

A, wood mice. B, young dormice.

So, we have a family group of dormice adults and young, plus wood and yellow-necked mice. And, yes, given access we would see brown rats too.

For more articles on wildlife see: http://www.nwhwildlife.org – scroll down for 100+ ad-free articles. Please feel free to comment as I / we may get things wrong or you may have ideas to add.

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