House Mouse (Mus musculus)

OTHER NAMES: Common House Mouse 
Latin Etymology: Mus ("mouse") musculus ("little mouse")

Adult House Mouse (subspecies M. m. domesticus) at Geddington, Northants - November 2016

Featured Subspecies: Mus musculus domesticus
Weight: 40-45g  /  Length: 12.5-20cm
IUCN Red List: Least Concern 

Perhaps of all vertebrates, the single species which has benefited most from humans - historically they are believed to have originated in Asia, but have followed humans to almost every location on earth.  They are adaptable omnivores, and given their fast reproductive cycle natural selection can change them quite drastically in a comparatively short amount of generations.  They are considered pests as they will damage human property although they are also the species from which domestic mice have descended.

Related Species:

Order: Rodentia 
Family: Muridae 
Genus: Mus 

SUBSPECIES: M. m. castaneus, M. m. domesticus, M. m. musculus, M. m. bactrianus, M. m. gentilulus

 - Sighting Locations -

UNITED KINGDOM - A very common resident, particularly in human inhabited areas though proportionately rarely seen

 - Seen at various sites including Geddington and numerous locations in London

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto .

Brown Rat (Rattus norvegicus)

OTHER NAMES: Common Rat, Street Rat, Wharf Rat, Norwegian Rat
Latin Etymology: Rattus ("rat") norvegicus ("of Norway")

Adult Brown Rat (subspecies R. n. norvegicus) at Geddington, Northants - May 2012

Featured Subspecies: Rattus norvegicus norvegicus

Length: 38-50cm  /  Weight: 230g

UK STATUS NOT EVALUTATED / IUCN Red List: Least Concern

A very adaptable and highly misunderstood creature - rats a very intelligent and expert survivors that have spread around the world with humans. They can be found in a broad range of habitats, although perhaps the most visible ones are urban ones where they are able to survive using food that humans leave. Originally reaching the UK aboard ships, it displaced the Black Rat which had reached the country first, making the latter more scarce. They were not responsible for the Bubonic Plague, but, may in theory carry other diseases. As with this individual photographed, perhaps the easiest time to see them is when they raid bird tables.

Related Species:
Order: Rodentia 
Family: Muridae 
Genus: Rattus 

SUBSPECIES: R. n. norvegicus, R. n.caraco, R. n. praestans, R. n. primarius, R. n. socer

- Sighting Locations -
UNITED KINGDOM - A common but usually shy resident
 - Seen at various sites including Geddington and Rutland Water

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto .

Eastern Grey Squirrel (Sciurus carolinensis)

OTHER NAMES: Squirrel, Grey Squirrel
Latin Etymology: Sciurus ("squirrel") carolinesis ("of Carolina")

Adult Eastern Grey Squirrel (Sciurus carolinensis - unknwon subspecies) at Regent's Park, London - November 2009

Featured Subspecies: Unknown
Length: 42-55cm  /  Weight: 400-600g
UK STATUS NOT EVALUTATED / IUCN Red List: Least Concern

A very common species found in parks and woodland throughout the UK. It is partially arboreal and can often be seen climbing in the upper reaches of trees, as much as it is on the ground. An introduced species, it carries parasites which are very dangerous to the native red squirrel population and as such the red squirrel has been replaced in much of its range by this species.

Related Species:
Order: Rodentia 
Family: Sciuridae 
Genus: Sciurus 
SUBSPECIES: S. c. carolinesis, S. c. extimus, S.c. fuliginosus, S. c. hypophaeus, S. c. pennsylvanicus

- Sighting Locations -
UNITED KINGDOM - An abundant resident - probably the most easily seen mammal in the UK
 - Seen at various sites including Geddington and Regent's Park

Further Notes: BirdForum Opus, IUCN Red List,  RSPB, Wikipedia, Xeno-canto  .

Stoat (Mustela erminea)

OTHER NAMES: Ermine, Short Tailed Weasel
Latin Etymology: Mustela ("weasel") erminea ("ermine")

Adult Stoat (subspecies A. a. stabilis) at Wooler, Northumbria - July 2009

Featured Subspecies: Mustela erminea stabilis
Weight: 260g  /  Length: 17-32cm
UK STATUS NOT EVALUTATED / IUCN Red List: Least Concern

Possibly the easiest to see of the UKs seven mustelid species, it is still however, quite an unusual occurrence to see one. It looks superficially similar to the weasel, but can be told apart by the substantially larger size and black tip to its tail. As with many mustelids, it is proportionally an incredibly powerful predator - killing animals many times its size and weight such as rabbits.  The Stoat in the UK remains brown throughout the year, but in more northerly populations they grow a thick white coat for camoflage during Winter, and it is in this form they are known as ermine and have been hunted for their fur in the past.

Related Species:
Order: Carnivora 
Family: Mustelidae 
Genus: Mustela 
SUBSPECIES: M. e. erminea, M. e. aestiva, M. e. alascensis, M. e. anguinae, M. e. arctica, M. e. augustidens, M. e. bangsi, M. e. celenda, M. e. cigognanii, M. e. fallenda, M. e. ferghanae, M. e. gulosa, M. e. haidarum, M. e. hibernica, M. e. initis, M. e. invicta, M. e. kaiacensis, M. e. kaneii, M. e. karaginensis, M. e. lymani, M. e. martinoi, M. e. minima, M. e. muricus, M. e. nippon, M. e. ognevi, M. e. olympica, M. e. polaris, M. e. richarsonii, M. e. ricinae, M. e. salva, M. e. seclusa, M. e. stabilis, M. e. stratori, M. e. tebedina, M. e. tobolica 

Further Notes: BirdForum Opus, IUCN Red List,  RSPB, Wikipedia, Xeno-canto .

European Water Vole (Arvicola amphibius)

OTHER NAMES: Water Vole, Water Rat
Latin Etymology: Arvicola ("field inhabitant") amphibius ("amphibious")

Adult Water Vole (subspecies A. a. amphibius) at Rainham Marshes, London - July 2010

Featured Subspecies: Arvicola amphibius amphibius
Weight: 200-350g  /  Length: 33cm
UK STATUS NOT EVALUTATED / IUCN Red List: Least Concern

Also (incorrectly) named the Water Rat, and thus star of the famous novel "Wind in the Willows", the Water Vole is a reasonably large rodent which lives, as its name suggests, along bodies of water. They live in burrows near ditches ponds and streams or occasionally in nests in reed beds. They unfortunately dramatically declining, in part because of the introduction of American Mink, but also habitat loss.

Related Species:
Order: Rodentia 
Family: Cricetidae
Genus: Arvicola 
SUBSPECIES: A. a. amphibius, A. a. hintoni, A. a. illyricus, A. a. italicus, A. a. jacutensis, A. a. jenissijensis, A. a. kuznetzovi, A. a. martinoi, A. a. meridionalis, A. a. musignani, A. a. ognevi, A. a. persicus, A. a. reta, A. a. stankovici, A. a. tauricus, A. a. terrestris

- Sighting Locations -

UNITED KINGDOM - An uncommon resident

 - Seen on several occassions at Rainham Marshes.

Further Notes: BirdForum Opus,  IUCN Red List, RSPB, Wikipedia, Xeno-canto .

Brown Hare (Lepus europaeus)

OTHER NAMES: Hare, Common Hare, European Hare

Latin Etymology: Lepus ("hare") europaeus ("of Europe")

Adult Brown Hare (Lepus europaeus - unknown subspecies) at Geddington, Northants - May 2012

Featured Subspecies: ?

Length: 53cm  /  Weight: 3800g

UK STATUS NOT EVALUTATED / IUCN Red List: Least Concern

The brown hare may initially seem like a rabbit but there are notable differences - the longer ears and more athletic build, not to mention the larger size in general being the main give aways. Hares also do not have burrows but sit upon the surface and hide - often they will not move until you are practically on top of them. It is typically a creature of field and grassland, but actually I've had some substantial luck in certain locations with wide grassy and rarely used paths through woodland bordering fields - it would seem that perhaps the lack of disturbance by machinery so often works may work in their favour.

Related Species: 
Order: Lagomorpha
Family: Leporidae
Genus: Lepus

SUBSPECIES: L. e. caspicus, L. e. connori, L. e. creticus, L. e. cyprius, L. e. cyrensis, L. e. europaeus, L. e. hybridus, L. e. judeae, L. e. karpathorum, L. e. medius, L. e. occidentalis, L. e. parnassius, L. e. ponticus, L. e. rhodius, L. e. syriacus, and L. e. transsylvanicus

- Sighting Locations -

UNITED KINGDOM - A widespread but local resident.

 - Seen at sites including Pitsford Reservoir, Trevose Head and Geddington.

Further Notes:  BirdForum Opus,  IUCN Red List, RSPB, Wikipedia, Xeno-canto 

.

Water Deer (Hydropotes inermis)

OTHER NAMES: Vampire Deer, Chinese Water Deer
Latin Etymology: Hydropotes ("water drinking") inermis ("unarmed")

Adult male Water Deer (subspecies Hydropotes inermis inermis) at Thornham Harbour - November 2020

Featured Subspecies: Hydropotes inermis inermis (Chinese Water Deer)
Weight: 9-14kg  /  Length: 77-100cm  
UK STATUS NOT EVALUATED/ IUCN Red List: Vulnerable

This small unusual deer species is native to China and Korea - it lacks any antlers at all, but is notable for it's large fang-like tusks, causing it to be classed as belonging to it's own subfamily with Cervidae. Despite it's native habitat of East Asia, it is notably seen in the UK; following escapee's from Woburn and Whipsnade a feral population has sprung uk in the East of England, and continuing to increase.

Related Species:
Order: Artiodactyla 
Family: Cervidae 
Genus: Hydropotes
SUBSPECIES: H. i. inermis, H. i. argyropus

 - Sighting Locations -

UNITED KINGDOM - An escapee from collections that has gone on to have a breeding population.

 - Two at Thornham Harbour

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

.

Eurasian Otter (Lutra lutra)

OTHER NAMES: European Otter, Otter, European River Otter 
Latin Etymology: Lutra ("otter") lutra ("otter") 

Adult Eurasian Otter (Lutra lutra) at Market Deeping, Lincolnshire - May 2026

Featured Subspecies: Lutra lutra lutra
Weight: 7-12kg  /  Length: 57-95cm 
NO UK STATUS / IUCN Red List: Near Threatened

A very widely distributed species found broadly across most of Eurasia where suitable habitat is available as well as some range in Algeria and Tunisia. Formally extremely rare in the UK due to pollution and persecution it has now reestablished in every county but remains a secretive and difficult animal to connect with.  They are primarily pescivorous but will expand their diet to wider prey as required. 
 
Related Species: 
Order: Carnivora 
Family: Mustelidae 
Genus: Lutra
SUBSPECIES: L. l. lutra, L. l. aurobrunnea, L. l. barang, L. l. chinensis, L. l kutab, L. l. meridionalis, L. l. monticola, L. l. nair
 
- Sighting Locations -

UNITED KINGDOM - A widespread but scarce resident

 - Seen at Market Deeping in 2026 

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

.

European badger (Meles meles)

OTHER NAMES: Eurasian Badger, Badger, Brock
Latin Etymology:  Meles ("badger") meles ("badger")

Adult European Badger (subspecies M. m. meles) at Weekley, Northants - January 2022

Featured Subspecies: Meles meles meles
Weight: 10-27kg  /  Length: 60-90cm
UK STATUS NOT EVALUATED/ IUCN Red List: Least Concern

Generally the largest terrestrial carnivore found in the UK by weight, the badger has a perculiar place in the country as a species that is very familiar but for most people rarely. One of the largest mustelids, they have a squat powerful build, evolved for digging and constructing their burrow-colonies known as sets. However, while they live socially, they actually disperse to feed and are relatively solitary as they seek out food. Almost entirely nocturnal, they are omnivores who will feed on a wide variety of foods if needed.

Related Species:
Order: Carnivora 
Family: Mustelidae 
Genus: Meles
SUBSPECIES: M. m. meles, M. m. marianensis, M m. heptneri, M. m. milleri

 - Sighting Locations -

UNITED KINGDOM - A widespread and numerous, but shy species.
 - Seen at Haweswater in childhood, and more recently at Weekley

Further Notes: BirdForum Opus, IUCN Red List, RSPB, Wikipedia, Xeno-canto

.