FROM RSPB BIOSECURITY MANUAL CHAPTER 2 - RODENT SURVEILLANCE & IDENTIFICATION - Rodent identification and signs of stowaways

Oct 12, 2026

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Provides guidance from the RSPB Biosecurity Manual for Chapter 2 on rodent surveillance and identification, focusing on recognizing UK target rodents and interpreting evidence left in the environment. Covers distinguishing droppings by size, shape, and consistency, including differences among brown rat, black rat, and house mouse, and discusses confusion risks such as rabbit, goat, shrew, vole, and invertebrate droppings. Includes methods to confirm species using photography and DNA testing, and outlines additional signs like nests, burrows, footprints, and rodent tooth marks.

LanguageEnglish

CategoryGeneral

FormatPDF

Pages7

Reading Time3 min

AccessFree to download

Rodent identification and signs of stowaways

Key features of UK target rodents

Identifying rodent droppings

Invertebrate droppings

Nests and other signs

Footprints

Rodent teeth marks

Rodent identification

FROM RSPB BIOSECURITY MANUAL CHAPTER 2: RODENT SURVEILLANCE & IDENTIFICATION Rodent identification and signs of stowaways Key features of UK target rodents Black rat House mouse FROM RSPB BIOSECURITY MANUAL CHAPTER 2: RODENT SURVEILLANCE & IDENTIFICATION Identifying rodent droppings Rodent droppings can be very variable (depending on diet), including in colour, but as a guide: | Brown rat | Black rat | House mouse | | --- | --- | --- | | -13-19mm long,
-3-4mm thick
-Rounded ends, one end may go toa point (as pictured)
-Likely to contain fur
-Often located in latrines along tracks, at feeding sites and on prominent rocks | -7-14mm long
-3-4mm thick
-Tapered ends
-Often slightly curved
-Likely to contain fur | -4-8mm long
-2mm thick
-Small and thin
-A bit like grains of rice
-Strong smell of ammonia. | | | | | Figure 2.9 Droppings of UK invasive rodents. Images: taken from Morton & Cole 2013 Rabbit or goat droppings be mistaken for rat droppings, though they are usually more spherical (particularly rabbit) and uniform. Goat droppings may be more cylindrical but with flatter or round, rather than tapered ends. Breaking up droppings should help (wear gloves): rabbit and goat droppings just contain vegetation, whereas rat droppings are likely to contain fur and a range of food stuffs. Shrew droppings – typically 2-4mm long and 1-2mm thick, these should be smaller than rat or mouse droppings. However, evidence from St Agnes and Gugh (Isles of Scilly) shows shrew droppings can be much larger than this. They are of a sandy consistency and are largely comprised of insect remains, whereas rodent droppings generally contain a wider array of food sources. Rat droppings usually contain fur as they are extensive groomers. Vole droppings are fairly uniform, cylindrical and tend to be rounded at both ends. Water vole droppings are 7-10mm long and 3-4mm wide and are those which are most likely to be confused with brown rat droppings. Rat droppings are usually tapered at one end (and are likely to contain fur/wider range of food sources) . Droppings from smaller species of voles cannot be distinguished, but their uniform nature may help distinguish them from mouse droppings. Wood mouse and yellow-necked mouse droppings look short and thick compared to house mouse droppings. Invertebrates, e.g. rose chafer beetles may produce piles offrass that could be mistaken for a rat latrine (right) . However, their droppings are likely to be more prolific and uniform. DNA testing can be done to confirm species. Droppings should be photographed in situ and then all of them should be collected, not just a sample. See the resource section 'Rodents-trapping and using bait legally' and the document called 'Necropsy, measuring and sexing rodents', for more details. Invertebrate droppings Rat prints in sand (above left), mud (above right) compared to tracking plate (below) Nests and other signs If you encounter baby rodents in a nest, install a trail camera to confirm the species, and take further action accordingly. Black rat Brown rat burrow and nest House mouse UK invasive rodent nests and burrows Burrow system of brown rat on coastal cliffs. Search for other signs around the entrances to a burrow system, such as droppings. Footprints | Black rat | Brown rat | House mouse | | --- | --- | --- | | 4 toes on front feet, 5 on rear 28-34mm long
Clear split in hind foot central pad | 4 toes on front feet, 5 on rear 30-42mm long
Solid hind foot central pad | 4 toes on front feet, 5 on rear 15-23mm long. | |
(not to scale) | | | Footprints of UK invasive rodent species. Note that the footprints of black rats shown here are similar to those which would be left on tracking tunnel plate, while those of the brown rat and house mouse are similar to those that would be left in a soft substrate such as mud, which allows more detail tobe [seen](seen www.pestdetective.org.nz)[ www.p

FAQs

How can droppings help identify brown rat, black rat, or house mouse?

Droppings vary in length, thickness, ends (rounded vs tapered), and may contain fur. The manual provides guide ranges for each species and notes ammonia smell for house mouse.

Why might rabbit or goat droppings be mistaken for rat droppings?

They can be confused by appearance, but rabbit droppings are usually more spherical and uniform, while goat droppings are often more cylindrical with flatter or rounded ends. Breaking up droppings can help: rat droppings are more likely to contain fur and a wider range of food.

How can species identification be confirmed when signs are unclear?

DNA testing can confirm species. The manual also advises photographing droppings in situ and collecting all droppings, not just a sample.

Oct 12, 2026

Upload by Liam