Sam Newton – Natural Heritage Trainee, Land of Iron
A single cow can produce over nine tonnes of dung per year, so across all domestic and wild herbivores imagine how this would quickly build up to mountainous proportions.
Fortunately there are many invertebrates whose life cycles involve clearing this up. Take Dung beetles – in the UK their annual role in the ecosystem is valued at £367 million, for cattle dung alone.
Dung beetles are a collection of around 60 species in the UK, within the Scarabaeidae family which also includes non-dung feeding Chafers and Stag Beetles). The actual dung feeders are split into the Aphodiinae (dwellers, residing within dung) and the Geotrupidae and Onthophagus (tunnellers, burying beneath dung). Contrary to popular belief there a no dung rollers in the UK, as this group are only found in the tropics and sub-tropics. The adults of all groups feed on liquid within dung, while the larvae eat the solids.
These 60 species utilise dung differently and so avoid competition – they use dung from different animals, they feed at different times of day or year, they live in different habitats and they favour dung of assorted ages. The fact that all the species vary in their ecology enhances the benefits provided in dung recycling to the wider ecosystem, helping fertilise the soil and enhance soil structure, and reducing greenhouse gas emissions.
In addition, dung beetles transport mites between dung piles, which feed on fly and worm eggs, thus indirectly helping reduce fly numbers along with some gastrointestinal parasites that can affect livestock.
Dung beetles also provide an important food source to many animals, for example Aphodius prodromus (a small Aphodiinae dung dweller), which is incredibly numerous in early spring when there are few other invertebrates available.
So Dung beetles are incredibly useful, as well as being beautiful (without mites) and valuable in their own right.
However, all is not well in the dung beetle world. A 2016 review found over 25% of UK species were ‘Nationally Rare’ (found in 15 or less 10×10km squares across the UK) and four may already be extinct.
Changing farming practises and the disappearance of livestock from historic pastures is a major cause of this decline in the UK. The loss of dung structure produced by modern livestock breeds fed high protein diets is also detrimental, as dung beetles essentially end up drowning in the dung. Soil disturbance is damaging to some species, and wormer overuse (e.g. Ivermectin can indirectly reduce larval development and survival) is perhaps the main cause of decline, ironically destroying the role dung beetles played in reducing parasitic worms naturally.
So how can people make changes to help conserve Dung beetles and their role in day to day biodiversity? If you keep any livestock, use faecal egg counts to reduce worming, consider keeping a few hardy livestock out during the winter if your land is suitable, also not removing all the dung from out of horse paddocks enables a constant supply of high quality dung. If you don’t keep livestock, try and support the keeping of native breeds which have better quality dung for a Dung beetle’s needs.
The Ancient Egyptians associated Khepri, god of the rising sun, with a dung beetle (a Scarab) which every day was believed to move the sun across the sky. While I’m not suggesting worshipping Dung beetles per se, we can try and appreciate these beetles, understand their predicament and even try and help.
There is a Dung Beetle UK Mapping Project. For lots of help with identifying between species, and to be able to record sightings and help build up a picture of distribution – see their website.
Apologies for the titular puns.