Crystal Maw, Royal Society for the Protection of Birds
The speaker began her career with the RSPB on Oronsay in the Western Isles, where she worked for three years. Here, the RSPB manage 50 cattle and 1000 sheep for the benefit of wildlife on the island, particularly to ensure the supply of nutritious dung beetle grubs which are critical for the survival of the island’s red-billed Chough population. This food source is found in cowpats.
The chough is an iconic feature of the island, but the Western Isles are at the northern limit of its distribution, and regrettably the population is in decline on Oronsay and Islay. The reasons for this are the subject of research and the speaker was tasked to establish a baseline database of the bird’s food consumption. This involved collecting and analysing the contents of cowpats, as well as sheep droppings. Her observations indicated that cowpats were entirely consumed by invertebrate larvae after 3 months, providing a rich source of food for choughs in the process.
Dung beetles in Australia provided a background to the research. The introduction of non-native cattle and sheep resulted in a build-up of dung, in the absence of any natural processes for its disposal. After careful experimentation, dung beetles were introduced from Europe and elsewhere. Some beetles are ‘dwellers’ in the dung, laying their eggs directly into it; others are ‘tunnelers’, taking a ball of dung into a burrow below it; others are ‘rollers’, rolling a ball away from the pat and hiding it. The introduction of dung beetles has solved the problem of disposal of cattle and sheep dung, and has had several other agricultural benefits.
Several other insects and their larvae are commonly found in cowpats. These include the common Yellow Dung Fly (Scathophaga stercoraria), the Sweat or Hover Fly, the Lesser Dung Fly (Sphaeroceridae), the Broad Centurian (Chloromyia Formosa), Clown Beetles (Histeridae), Dor Beetles (Anoplotrupes stercorosus), Night-Flying Dung Beetle (Acrossus or Aphodius rufipes), and several other types of the Aphodius genus of beetles. All the larvae are easy to find in the cowpats, hence their importance as a food source.
D.F.D