GORDON D’ARCY

Natural SCAVENGER

BY GORDON D’ARCY

We may not like to dwell on the subject of scavengers but there is no escaping the scavengers that dwell on us. Microscopic demodex mites live in hair follicles and feed on our sloughed skin cells. Provided they don’t multiply and cause an unpleasant skin condition they provide a useful (if somewhat distasteful) ex-foliating function on the human body. ese mites are representatives of hordes of miniscule invertebrate scavengers that perform vital clean-up work throughout nature, the absence of which would quickly reduce our world to an odorous ‘tip’.

In general, scavengers are regarded negatively. We know they are there but we like to keep them at a distance: we do not like our sanitised notion of nature to be ‘contaminated’ by them. ere is, nevertheless, no escaping their importance in ecology.

It is among the birds that we become most aware of scavengers. Take the noisy, gregarious starling, famous for the spectacular murmurations. Starlings re ect their amazing collective intelligence from an early age. No sooner have they le the nest than hordes of brown juveniles, gather on the shore. Working together as an avian meitheal they seek out the abundant food stocks hidden in the accumulated seaweed along the high tide. De ly icking over the rotting fronds they extract seaweed y eggs and larvae, sand-hoppers and any other exploitable jetsam. e little seaweed-coloured rock pipit has been so successful at this activity that it occurs exclusively all around the Irish coast. Jackdaws and rooks will join in the foraging when it suits but they generally prefer agricultural land to the open coastline. One species, however, the hooded crow, has made an art-form out of shore scavenging. By ying up to the requisite height, hovering and dropping anything from a winkle to a mussel, to be smashed on a rock below, the ‘hoodie’ has cornered a particular scavenger’s market to itself. Herring gulls will try the same method but as o en as not the mollusc

will refuse to open having been dropped on a seaweed-covered rock or a grassy verge. Herring gulls, have succeeded in giving scavengers a particularly bad name due to their chaotic land ll assemblages and their annoying tendency to harass people for scraps in urban settings.

Most of our mammals, whether considered primarily predator, or prey species, are also scavengers. Dare we when necessary. When the nocturnal ramblings of the fox take it along the high tide it too will feed on the available tit-bits and on any unsuspecting tit-bit foragers with which it comes in contact. ere is no denying the vital service provided by the likes of crows and foxes in clearing up road-kill. Scorned though they o en are, how much additional contagion would exist in the wild, in farm livestock, even in humans, were it not for these roadside corpse-cleaners? Historically, human preoccupation with cleanliness has cast many important scavengers into the metaphorical refuse bin. In more unsanitary times the red kite (one of most e ective refuse collectors), gained the rather uncomplimentary moniker of ‘shite-hawk’. Vili cation of this kind and the steady destruction of its woodland 'MOST OF OUR MAMMALS, habitat resulted in its disappearance from Ireland in the early 19th century. WHETHER ankfully, a more CONSIDERED enlightened attitude has PRIMARILY supported the successful PREDATOR, OR PREY SPECIES, ARE ALSO reintroduction of this most useful and beautiful raptor. e African lappet-faced vulture was also subject to SCAVENGERS'. ignorant vili cation which almost brought about its extinction. Erroneously regarded as a livestock killer due to its readiness to feed on carcasses, this magni cent raptor was seen as an undesirable presence on the African savannah. Trapped by pastoralists, poisoned with bait laid for jackals and shot by tusk-hunting poachers, this vulture had declined to endangered status by the turn of the millennium. Just in time, however, its unique function in opening the tough hide of mammalian carcasses was realised. By exposing the innards with its huge hooded beak and rendering them available for consumption by a host of other scavengers – from other vultures to jackals and hyenas – diseases consider the rat? Our highly successful such as botulism were greatly reduced. brown rat is the quintessential scavenger e lappet-faced vulture is still of all kinds of refuse whether ‘natural’ or endangered but a new appreciation of its human. As likely to be found along the role should ensure its future. shore as a sewage outfall, this much- In these days of economic ‘nature-rating’ vili ed creature has been performing its (as in the much-debated notions of Natural scavenging duties since its (inadvertent?) Capital and Ecological Services), it behoves introduction in the Middle Ages. ough us to re-evaluate our relationship with our less appropriately designed for the job, scavengers. A er all, they are closer to us mice, voles and even shrews will scavenge than we think!