Tuesday, July 26, 2011

The unsung beauty of dung

Fresh cow dung is wonderful stuff.  Gooey, smelly and, perhaps surprisingly, a hive of activity.

The meadow at Flitwick Moor has heaps of the cow-pats courtesy of these guys and girls.
I've never taken time out to sit and stare at a cow-pat before. Today I did. Fascinating. Little beetles, which looked a bit like water beetles, were zapping in and out of holes in the pats like whippets mainlining on caffeine.

I tried hard to get some decent shots of these beetles, but they were just too fast for me. These are the best shots I could get.
I am pretty sure these beetles are Sphaeridium scarabaeoides; a terrestrial water beetle. A very similar species is Sphaeridium lunatum. Their ecology is essentially the same. They are about 6mm long, shiny black with a goldie bottom and red patches on their elytra. Pretty smart looking apart from being a bit streaked with poo.

S.scarabaeoides live exclusively on cow-pats (Otronen & Hanski, 1983), and they like 'em fresh. The adult beetles are coprophagous; they eat dung. They live on, eat and have sex in fresh, wet cow-pats. To them a sloppy wet cow-pat is like The Dorchester. 

S.scarabaeoides larvae are carnivores; they predate fly larvae in dung (and eat each other when maggots are in short supply (Sowig, 1997)). Here are some tiny flies laying eggs on the cow-pat and a green bottle-type fly, possibly Orthellia cornicina, whose larvae also live in dung.
Heaps of invertebrates utilise cow-pats as a habitat. As cow-pats are ephemeral habitats these creatures can locate fresh pats very rapidly (Otronen & Hanski, 1983) and their larvae develop very fast (Sowig, 1997). These beetles and flies are the first colonists of cow-pats. Adult beetles start arriving within 2 hours of cow-pat deposition and it's not unusual to find over 50 adults on/in a pat (Otronen and Hanski, 1983).
Cow-pats themselves are wonderful to study because they are tiny habitat islands distributed randomly within pasture; the surrounding pasture is not suitable for these specialised beetles. How they find pats and colonise them fascinates ecologists.

Anthelmintics (Ivermectin/Avermectin) are broad-spectrum anti-parasitics, introduced in the 1980s to treat cattle. Drug residues persist in faeces and are thus a threat to invertebrates that live in dung, reducing their density and diversity (Vickery, et al., 2001, Beaumont, 2005). If there are less insects in dung, then this also potentially reduces the food available to foraging birds (Vickery, et al., 2001).

Dung insects like these little beetles are vital in meadow and pasture ecosystems (Webb, 2004). They are the invertebrate equivalent of Tudor gong farmers (nightsoil collectors); a dirty job, but absolutely vital to the healthy functioning of communities. 


Addendum:
I also took a photo of a fly I didn't identify at the time.
From reading Stand and Stare blog, I think this may possibly be a noon fly (Mesembrina meridiana), another dung laying species.

References
Beaumont D  (2005) Avermectins and dung Insects. Conservation Science Review, Number 43. RSPB. PDF available here.
Otronen M and Hanski I (1983) Movement patterns in Sphaeridium: differences between
species, sexes, and feeding and breeding individuals. Journal of Animal Ecology, Volume 52, pages 663-80. Available here.
Sowig P (1997) Predation among Sphaeridium larvae: the role of starvation and size differences (Coleoptera Hydrophilidae). Ethology Ecology & Evolution, Volume 9, pages 241-51. Available here.
Vickery JA, Tallowin JR, Feber RE, et al., (2001) The potential value of managed cereal field margins as foraging habitats for farmland birds in the UK. Agricultural Ecosytems and Environment, Volume 89, pages 41–52. Available here.
Webb L (2004) The Dung Beetles (Coleoptera: Scarabaeidae and Hydrophilidae) of Ayrshire, Scotland. Bulletin of the Amateur Entomologists’ Society, Volume 63. Available here.

There were some common lizards hanging about in the meadow too. I only managed to catch one on the camera, from a distance.
NOTE
I must acknowledge the considerable help I received from my 5 year old niece when writing this blog entry at 6am this morning.

7 comments:

  1. Did you know there's a fellow cow pat enthusiast on the web at http://standandstare-nyctalus.blogspot.com/2009/05/this-is-noon-flymesembrina-meridiana-if_21.html#comment-form

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  2. Wow, now here's something that I never would've thought of investigating.... But you've shown that, indeed, there's fascinating stuff to be learned EVERYWHERE! Great post!

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  3. Hi Phil. Thanks for heads up. We dung devotees ought to stick together. M

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  4. Greetings Mel! What a great post. Dung is cool (except when fresh) but there does seem to be a limited group who share this view. Mind you, I have not spent as much time with my nose stuck in it as you clearly have.
    The difficulty in laying hands on a copy of 'Insects of the British Cow Dung Community' by P Skidmore remains a sadness (nice name that -the more you study them, the more you stand in, so you do in fact Skidmore).
    I don't know how I've missed your blog - looks great so I've got some back reading to catch up on...
    Best wishes, Allan

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  5. You'll be pleased to hear a report from a birder in North Kent today:
    A rare Maid of Kent beetle was found in a cow pat on The Swale NNR this morning by one of the Vol. Wardens
    Also last year at the same time.....
    http://www.bbc.co.uk/news/uk-england-kent-10957374

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  6. :-) Trowels at the ready then.....
    Now that's one amazing hairy-bumblebee-mimicking rove-beetle-creature I'd love to see.
    Deep sigh.

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  7. Update: I just bought the Skidmore book from Amazon for £2.95. Amazing bit of luck! May even have my hands on it by the weekend :-) so will have something to do if it rains.

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