Nature 2009 June

Socialising – ‘Whilst many a mingled swarthy crowd – rook, crow, and jackdaw – noising loud’

Weathewise, June is the month by which we judge how good our summers are. The rare occurrence of a ‘flaming June’ somehow dictates our impression of the season as a whole. Take 1976, which we oft quote as the benchmark on which all summers are to be judged. It was characterised by an all but perfect June. True, July and August were also sunny but that is not so unusual. My conclusion is that it’s the length of the summer season that stands out in our memories not the occurrence of scorching hot days. So what about this year? Although the Met Office has announced it will be a ‘good summer’, folklore contradicts this with the first cuckoo late announcing its arrival this year (25 April). The only other prediction I will make is that rain will not interrupt play on Centre Court this year!

I was the witness at a wedding a month or two back. Not a wedding I had been invited to and not one involving just a single couple but one with many, many participants. It was a noisy affair but there were no humans involved. It was a ‘crows’ wedding’ but there were no crows involved. Instead, each day from late January for several weeks, there were normally over a hundred rooks flying in tight formation, stalling and stumbling. Why is a conflagration of rooks assigned to crows? Rooks and crows are closely related of course and at a short distance both birds look black but rooks have shiny feathers which in sunlight have an ‘oil-on-water sheen’ of blues, bronzes, purples and mauves. So what is going on at such ‘weddings’? Rooks are the most intelligent and sociable birds of the ‘corvid’ family (rooks and crows, etc) while crows lead a mainly solitary existence.

Maintaining good relations in a crowded community necessitates order, customs and conventions. Rooks achieve this by having rules reinforced by a complex vocabulary; some say up to 30 distinct calls. Younger birds joined in to learn the ropes and practise these elaborate flights ultimately aimed at establishing pairings and hierarchies in the rookery. As the days went by many couples cemented a relationship by synchronising their displays. Victorian writers did not try and distinguish rooks from crows, both of which were imbued with age old affiliations with death and disease and were equally blamed for their destructive abilities and scourge of arable land. Rooks in particular outnumbered crows by a hundred to one, so it remains a bit of a mystery why we have ‘scare crows’ and not ‘scare rooks’. We may describe distances in terms of ‘as the crow flies’ yet it is the rooks in their hundreds, rather than crows, that are known for long, straight flights up to 25 miles returning to their roosts. Much like a rook in a ploughed field, I unearthed this tasty morsel, part of a longer poem about the month of January by the 18th Century poet John Clare, which paints for us a still relevant picture:-

Whilst many a mingled swarthy crowd –
rook, crow, and jackdaw – noising loud,
Fly to and fro to dreary fen,
Dull winter‘s weary flight again;
They flop on heavy wings away
As soon as morning wakens grey,
And, when the sun sets round and red,
Return to naked woods and bed.

One interesting find, summing up the love-hate relationship with the rook, was an account of how colonists to New Zealand in 1874 took rooks with them. Some writers, somewhat romantically, have said this was to remind the émigrés of the ‘Old Country’. Not at all, despite their lessthan- harmonious relationship with man, they were seen as ideal pest controllers to deal with insect infestations prevalent in the South Island. Rook populations may have fallen in the UK but are on the increase down under and there are serious concerns they will become a major pest in their own right in the North Island. Another reminder of animals living in an unusual association with humans came from a recent conversation about the arrival on someone’s doorstep of some wild but highly sociable bees, living happily in the crevices beneath the brickwork – a source of neither damage nor danger. Bees are the most highly developed of all insects. Although the colonies of honey bees may seem to be the ‘bee’s knees’, these housesitter bees are in fact the top of the beepyramid. These bees have developed a specialised trade, wood-boring or leaf-cutting for example. Many of them have consequently sacrificed their ability to bite or sting. So to insure their progeny are protected against predation, they live as individuals but in a loose, but sociable community preserving their individuality but adopting a level of give and take with their neighbours. These bees are in fact the most ‘socialised’ of all bee societies, proving the motto ‘Good fences make good neighbours’. The next group of bees and the largest of all are in fact strictly solitary, shunning publicity. Some are even aggressive towards their own kind and prime candidates for a bee ASBO for their persistent unsociability. Honey bees represent the third way.

A highly ordered, sociable community sacrificing individuality for an impressive organisation of labour, comprising foragers, defenders and egg producers (queens and drones) all locked together by an advanced form of communication. Man has harnessed this community living to his own ends, exploiting their industry as pollinators and harvesting the fruit of their labours. A few thousand years of intensive bee husbandry may be having disastrous consequences. Colony Collapse Disorder is the name coined for the yet-to-be- determined cause for rapid decline in bee communities right around the world. Some of the possible reasons for the declining numbers could be a bee plague, pesticides, or malnutrition. If the commercial bee community were to collapse totally within as little as three seasons, fruit and vegetable food production could have all but ceased. The consequences for food production would be devastating on the human population. I don’t normally recommend a walk amongst the nettles but if the harsh winter has not taken too heavy a toll a third brief example of sociability to look out for are the colonies of small tortoiseshell, peacock or red admiral caterpillars clustered tightly on the freshest leaves. Safety in numbers and co-ordinated reactions to predatory wasps protect the vulnerable larvae and ensure a healthy population of butterflies to socialise in your garden or up and down the hedgerow.