North East Harvest Mouse Survey 2017

Once again we would be delighted if you would like to help with Northumbria Mammal Group and Durham Wildlife Trust’s Harvest Mouse survey this year.

The Harvest Mouse is a very interesting species in this region as it was long thought that the Tees Valley was the northerly limit of its distribution nationally, with only sporadic records further north. However, results from the surveys we have conducted in the past three years suggest it could simply have been overlooked and the higher (though still quite small) number of records in the Tees Valley could largely be the result of greater survey effort.

Harvest Mouse – Margaret Holland

This survey was originally devised by the Mammal Society but due to operational reasons they were unable to continue with it. Northumbria Mammal Group and Durham Wildlife Trust stepped in at the last minute three years ago to continue it in this region.

The Mammal Society’s survey involved searching set areas of habitat for a set period of time to give an indication of relative abundance. However, the aim of the survey in this region is just to establish the extent of Harvest Mouse distribution across the North East so we are concentrating on finding signs of its presence rather than comparing its population at one site against another.

1. Before you start
If you would like to take part in the survey please make sure you have registered that you will be doing so by contacting either Vivien Kent or Ian Bond on
We don’t allocate people specific areas to survey so anyone can survey any suitable bit of habitat at a time and location that is convenient for them. However if you would like to discuss possible locations please get in touch with Ian or with Vivien.

Please ensure that you ask permission from the landowner before surveying at any sites that does not have open public access. Taking part in the survey doesn’t grant any right of access so please be courteous and understanding if permission is refused.

The survey looks for Harvest mouse nests, but any records of Harvest mice including any historical ones that you might come across, for example by talking to farmers, would be greatly appreciated.

Harvest Mice will continue to breed into November so please leave the nest where you found it if surveying in early November. However the mice do not re-use their nests so it is acceptable to remove them for evidence if found any later than that.

2. Looking for Harvest Mice Nests

Harvest Mice themselves are very difficult to find so the survey concentrates on finding their distinctive nests. What makes a Harvest Mouse nest distinctive is that it is woven into the living leaves of the grass, which the mouse then shreds and weaves together. The nest is so tightly woven that often an entrance hole isn’t visible. Harvest mouse nests are built off the ground, which may be up to 1m in reeds or just a few centimetres in a clump of cocksfoot. The nests are spherical rather than dome shaped as in a bird’s nest and can be the size of a tennis ball for a breeding nest or just the size of a ping-pong ball for a day nest.

Harvest Mouse Nest – Martha Crowell

Harvest Mice habitat can be found in areas of tall, dense grass (grass includes reed-like plants and cereals). The easiest places to find Harvest Mouse nests are in tall grasses such as Common Reed or Reed Canary Grass. The other likely location is in clumps of Cocksfoot grass where the nest usually sits inside the clump but off the ground.

When searching amongst Cocksfoot it is best to find a spot with an area of Cocksfoot that is 10m*10m or more (or the linear equivalent) rather then looking through isolated clumps. Other grasses, including some tall grasses such as False Oat Grass tend to be too weak to support Harvest Mouse nests. However their nests can also be found in the bases of hedges where the hedge plants give some support to weaker grasses and also in plastic tree tubes that have grass growing through them.

You would be very unlikely to find Harvest Mouse nests among grass that is mown or grazed or among tall but weak-stemmed grasses. They are also unlikely to be present in woodlands or other habitats that do not have areas of tall, dense grass.

Harvest Mice nests are quite distinctive in certain circumstances, e.g. when they are clearly elevated in vegetation however, there is still scope for confusion with nests of other species so if you do find a likely nest then please try and take photograph for confirmation if possible.

Harvest Mouse Nest in Seaham – 2016 Survey

3. Once you’ve finished
Once you have finished your survey please send us details of the:
Grid Ref (minimum 4 figures)
Date of survey
And don’t forget to let us know your name and, of course what you found (or didn’t find).
Please send any results, positive or negative to Ian Bond or Vivien Kent.
Any other wildlife records that you make are also very valuable and can be passed directly to the Environmental Records Information Centre North East (ERIC) or passed to Ian or Vivien who will collate them and pass them on to ERIC and the relevant Wildlife Trust.
Any queries

Please contact Ian Bond at or Vivien Kent at

Good Luck!


The Health & Safety Bit
Please read and follow the following guidelines – while most will seem like common sense, it is highly recommended that you do follow these when carrying out your surveys.
As a volunteer you are under no obligation to participate in this survey and you can cease taking part in the survey at any point. You are responsible for your own health and safety and should never put yourself or others in a position that could be dangerous. If at any point you have concerns about your own health and safety or that of others, you are strongly advised not to undertake/continue the activity.
Please take care while carrying out your surveys. Surveying in the vicinity of water can be hazardous, so where possible work with another responsible person. Northumbria Mammal Group can take no responsibility for personal injury incurred by volunteers during the course of their surveys.
Personal equipment –You are advised to wear appropriate clothing and footwear for the terrain and weather conditions you are working in. The weather can be unpredictable, especially at this time of year, so ensure you have suitable clothing for all weather conditions. Wear gardening or work gloves and long-sleeved clothing to protect your hands and arms from thorn or rough vegetation while carrying out the survey. Carry a torch, spare batteries, a compass, whistle, first aid kit, water and high energy food. If working in remote locations, consider taking a survival bag.
Lone working and contact – If possible avoid lone working. If this is unavoidable, before you go into the field ensure that you inform a responsible person of where you going (for more remote areas a grid reference is particularly advised) and when you expect to return; how you intend to travel to and access your site, and who to contact if you do not return when expected. Consider also leaving your vehicle registration details if relevant, with a responsible person. Ensure that you have a well-formed contingency plan if you do not return when expected. Always carry a fully-charged mobile phone with you. Mobile phones may not work in remote areas and it is advisable to locate the nearest public telephone box or nearest inhabited house to your survey site.
Weather – Be aware that hazards may increase in rain, strong winds, snow and thunderstorms. If bad weather is forecast or encountered, do not commence your survey, or cease if you have already started. It is recommended that you do not survey in heavy rain, sleet, hail, snow, strong winds, thunderstorms or very cold weather.
Assessing your site – All surveyors should consider the particular hazards that are associated with their site/s. Identify potential hazards before commencing your survey. Assess your individual circumstances and medical conditions in relation to the potential hazards on your site before choosing to undertake the survey.
Livestock – Care should be taken when entering areas with livestock, particularly cattle, rams and horses. Do not enter fields containing bulls and be especially careful around cows with young calves as they can be particularly protective of their young. If you have any concerns, remove yourself from the situation. Rutting deer can also be aggressive in autumn. It is not advised that you take a dog with you while surveying. If you intend to take your dog while surveying, ensure that you keep it on a short lead and under control at all times.
Farm machinery – Farm machinery should be avoided and not touched at any point. Avoid fieldwork in close proximity to any working farm machinery.
Terrain – Please take extra care when surveying along watercourses, cliff edges, ditches, areas of boggy ground, reed beds and loose rock, as well as general rough terrain. Wear appropriate footwear and never cross rivers unless via a bridge. Avoid hazardous areas such as quarries, railway lines, busy roads and ravines, and do not attempt to climb steep slopes, walls or fences. If fieldwork is being carried out along roadsides, wear bright-coloured clothing, or preferably a high visibility vest. If walking along roads, ensure that you face on-coming traffic. Take particular care on blind bends in the road and have somebody keeping watch for traffic.
Where possible avoid very muddy or boggy areas. If moving through these areas is unavoidable, test every footstep on the ground before putting your weight on your feet. Proceed slowly and push a stick into the mud to test its consistency and depth before proceeding. Do not wear waders to carry out this survey or enter any water deeper than a shallow puddle. Look out for hazards in wooded or scrubby areas such as low or fallen branches.
Human confrontation – If you have any concerns about your personal safety at any point then cease surveying and remove yourself from the situation. Avoid working alone. Consider the privacy of residents, particularly when working and around residential areas.
Daylight hours – Do not survey in dusk or at night. Ensure you give yourself enough time to carry out the survey in daylight hours, bearing in mind the short winter days of the survey period. Carry a torch and spare batteries as a back-up.
Disease – Volunteers may be exposed to disease during survey work. This can pose a hazard to humans and also to wildlife.
Cuts or abrasions of the hands should be covered by sticking plasters or rubber gloves. Take particular care with these simple precautions at sites where brown rats are common since there may be a risk of Weil’s disease; also where you may encounter dog faeces as this can present a risk of Toxocariasis. Wash your hands after completing your survey and before eating, drinking or smoking.
To reduce the risk of spreading any disease (especially water-borne), ensure footwear and outdoor clothing is cleaned before and after visiting a site to carry out the survey. Follow any bio-security measures in place on the land you are surveying, e.g. use disinfecting mats at gates etc.
If disease is expected or you feel unwell at any time after carrying out the survey, then consult your doctor immediately, explaining the type of fieldwork you have been involved with and where you have been carrying it out.
By taking these precautions you are reducing the risk of contracting any disease, however, the following diseases can have severe effects and in rare cases can be fatal.
Tetanus – Caused by the bacterium Clostridium tetani, a common micro-organism found in soil. This infection of minor wounds and scratches can result in tetanus. All skins wounds should be covered before fieldwork is commenced and anti-tetanus treatments should be kept up to date. Always wash your hands after completing fieldwork and before eating, drinking or smoking.
Leptospirosis (Weil’s disease) – This bacterium is carried by rodents, particularly rats and is excreted in their urine. This disease is commonly found in water. As for tetanus, ensure that all wounds are covered and avoid contact with water that may have been contaminated by rat or cow urine. Wash hands thoroughly before eating, drinking or smoking. If you suffer from flu-like symptoms following field-work, contact your doctor immediately and mention Weil’s disease.
Lyme disease – The bacterium that causes Lyme disease is transmitted via the ticks of various species, including deer, sheep and pheasants. While surveying in long grass or forested areas, check exposed skin for ticks and if found remove. Tuck trousers into boots or socks and wear light-coloured clothing to enable ticks to be seen more easily before they attach themselves to you. Ticks are unlikely to be a problem during the winter months. If you suffer from flu-like symptoms following fieldwork, especially (nut not only) if you found a tick on you after the survey, contact your doctor immediately and explain that you may have been exposed to Lyme disease.
Tick-borne encephalitis – This is a viral disease carried by animal ticks. There is a vaccine for this disease if prolonged exposure to tick-infested areas is a possibility. In Britain and Ireland a similar disease known as ‘Louping ill’ is also present. This is particularly associated with grouse and hares in moorland regions and has similar symptoms to tick-borne encephalitis, ranging from flu-like symptoms to severe symptoms requiring hospitalisation. It is incredibly rare in humans.
Salmonellosis – This bacterial infection is common in rats and mice. If the bacterium is ingested as a results of poor hygiene, then mild to severe food poisoning will occur.
Toxocariasis – This is a rare infection caused by roundworm parasites which are commonly found in cats, dogs and foxes. The parasites can be passed on to humans by contact with the faeces of these animals. Symptoms can include, a cough, fever, stomach pain or headaches, but more serious symptoms can occur and infection can lead to damaged sight. Use gloves while carrying out the survey and wash hands thoroughly afterwards and before eating, drinking or smoking. Contact your doctor immediately if you have any symptoms of illness after carrying out the survey.