Aging dormice shorten their hibernation for more reproduction

Date:  October 31, 2018

Source:  University of Veterinary Medicine -- Vienna

Edible dormice are extremely long-lived for their size thanks to their seasonal dormancy. The animals are veritable record holders in this "discipline," with hibernation periods lasting between at least six and a maximum of eleven months. The factors influencing the variable duration of the hibernation period, apart from the specific environmental conditions, have so far been unknown. Researchers at Vetmeduni Vienna hypothesised that older animals should shorten their winter dormancy in favour of a reproductive advantage. This hypothesis has now been confirmed in a database analysis, published in Scientific Reports, of dormice populations living in large outdoor enclosures. The shortened winter hibernation of aging males and females were due to an increase in reproductive activity. Older animals also delay the onset of hibernation and emerge earlier in the season.

Mammals usually have a clear correlation between body size and life history, with smaller species tending to have a shorter lifespan. Various strategies exist, however, through which small mammals, including several species of rodents, can extend their lifespan. One of the most successful of these strategies, besides flight or arboreality to escape ground predation, is hibernation. Animals like the edible dormouse (Glis glis) hibernate to avoid predators and to get through seasonal periods of low food availability. Dormice are true "sleepyheads," with an average length of dormancy between eight and nine months. The benefit of torpor, with a considerably reduced metabolism, is an exceptionally high life expectancy of up to 13 years. This makes them the Methuselah among the otherwise short-lived small rodents.

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More woodland management needed to help save dormice

June 26, 2018, University of Exeter

Managing woodlands to a greater extent could help stop the decline of Britain's dormice, new research suggests.

Dormouse numbers are falling in Britain—down by 72% in just over 20 years—and the scientists say this could reflect changes in climate and the composition and structure of woodland habitats.

The findings, from two new studies led by the University of Exeter, show dormice favour woodland with varied heights and areas of regrowth, including species such as hazel and yew that provide the flowers, fruits and nuts they enjoy.

The researchers call for a return to active woodland management, which can include coppicing, glade creation and small-scale tree felling, to create a "mosaic" of trees of different ages and sizes, especially areas of new growth and medium-height trees.

Dormouse numbers are higher in woodlands with more varied tree heights and scrubby areas, and they prefer to use areas of woodland edge, and dense trees and shrubs, when they move around at night.

"Habitats that we found to be good for dormice have been in decline," said lead author Dr. Cecily Goodwin, of the Environment and Sustainability Institute on the University of Exeter's Penryn Campus in Cornwall.

"Dormouse conservation would benefit from more broadleaf woodland in the landscape and more diverse woodland structure—ranging from new growth and scrub to mid-height woodland to old trees.

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Dormice in Britain 'vulnerable to extinction'

By Claire Marshall BBC environment correspondent

9 September 2016

Britain's native dormouse has declined by more than a third since the year 2000 according to a new report by wildlife charity, the People's Trust for Endangered Species.

The State of Britain's Dormice report also shows that hazel dormice are extinct in 17 English counties.

The researchers assessed more than 100,000 records gathered from across the UK over 25 years.

The report says the dormouse is now vulnerable to extinction in Britain.

Since 1998 trained volunteers around the country have been gathering data on the tiny hazel dormouse (Muscardinus avellanarius). It is one of the longest-running small mammal monitoring projects in the world.

The creatures live mainly in hedgerows and woods, weaving ball-like nests in the undergrowth from bark in the summer and hibernating on or near the ground in winter between October and May.

They are extremely tricky to locate - a populated area the size of two football fields will only contain four dormice. A giveaway sign is a nibbled hazelnut.

'Dramatic decline'

Today's report shows that they are more difficult to find than ever. Over the last 16 years, the population has declined by almost 40%. Populations are now restricted to the Welsh borders and southern England. They have never been recorded in Scotland or Northern Ireland.

Ian White is dormouse officer at the People's Trust for Endangered Species. He has been monitoring the species for the last decade and describes the decline as "dramatic". He says: "Dormice have been around for 40 million years, but their future in Britain is now precarious and there's a pressing need for action to ensure their long-term survival."

In 1885, dormice were present in 49 English counties; today, they're known in 32 - excluding those counties where they have been reintroduced.

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Dormice 'take naps to aid chances of survival'

2nd July 2014

By Victoria Gill

Science reporter, BBC News, Manchester

The notoriously sleepy dormouse may be even sleepier than previously thought and researchers say naps help the animals survive until hibernation.

Researchers in Vienna found that when less food was available, garden dormice used a short sleep-like state called torpor to save energy.

The animals also appear to use torpor when the weather is colder.

They presented their findings at the Society for Experimental Biology's annual meeting in Manchester, UK.

Lead researcher Dr Sylvain Giroud from the University of Veterinary Medicine, Vienna compared dormice that had unlimited supplies of food with those that were fasted on alternate days.

The food-restricted dormice used torpor more frequently and entered the sleep-like state for longer than those animals that were able to feed freely.

While they are in this state, their metabolic rate slows and their body temperature is reduced, which saves energy. This allows the animals to store more body fat, which is crucial for their winter survival.

"This shows how the wild mice cope with the unpredictability of food," explained Dr Giroud.

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Reintroduced dormice thriving in Cambridgeshire wood

Dormouse doing well in Bedford Purlieus Wood.

Branching out - dormouse on the march in Peterborough wood

November 2012. Dormice are thriving in a Peterborough wood - and now a local farmer is helping then to branch out even further afield.

The Forestry Commission found 27 dormice in boxes in Bedford Purlieus Wood, near Peterborough, during the final monthly check of the year in October. Adults, juveniles and babies were recorded, most in good health and with plenty of fat to see them through their winter hibernation.

The checks - carried out by rangers and volunteers - have been crucial in charting the progress of the endangered mammals since they were released in the 200 hectare beauty spot in 2001 after becoming extinct locally.

Cheryl Joyce, Forestry Commission ranger, said: "Finding so many dormice in our final check is great news. But what has really excited us is that some animals were found a long way from the original release point, adding to our hopes that they might soon spread into the surrounding countryside. That really is the next major project landmark. It just shows what sensitive habitat management allied to the passion of volunteers can achieve."

Dormice boxes
Spurred on by the dormouse revival, Clive Fuller from 1150 acre Cross Leys Farm, is working with Cambridgeshire Wildlife Trust and volunteers to erect boxes in hedgerows in his fields bordering Bedford Purlieus Wood. 

Read more:  http://www.wildlifeextra.com/go/news/dormice-cambridgeshire.html

Dormice whiskers aid tree-climbing

Dormice use their whiskers to help them climb trees, researchers say.

By twitching them upwards, outwards and straight ahead up to 25 times a second, they sense where they are going, a University of Sheffield team has found.

The process, called whisking, is used by some other rodents, and by whiskered mammals including seals and walruses.

Dr Robyn Grant, from the university's Active Touch Laboratory says whisking is "a parallel sense to our sense of touch".

She says hazel dormice (Muscardinus avellanarius) use their whiskers, or vibrissae, in a similar way to how people use their eyes - scanning to recognise what is in front of them.

"Because of the uneven surface on branches, they vibrate them to find where to put their feet, as well as to work out where there's a gap and where to change branches," says Dr Grant.

Dormice are endangered in the UK and hibernate most of the year in small nests on the ground, but in the summer they live in trees.

Dr Grant says that they can also use the sensory nodes in their whisker follicles, which respond to the vibrations of their whiskers. This helps them to locate and determine the size, shape and quality of a food item, or to sense their way home.

Continued:  http://www.bbc.co.uk/nature/18237655