Gizzard Stones
I live in a half-timbered cottage built maybe four hundred years ago, with beams and wainscots and mantle-pieces. I use my mantle-pieces, like generations of my family before me, for storing completely useless objects that I don’t want to throw away. One of these is a small piece of polished oak about six by four by two inches with six inverted square conical shapes neatly carved out of the large face. I haven’t the vaguest idea what it is. I found as it in a derelict pub along with a Victorian policeman’s one-candlepower bullnose lamp and they both sit on the mantle-piece alongside a wooden toad of a similar vintage carved by my brother from a bit of Weymouth pine, with eyes painted black and yellow using a paintbrush made of hairs cut from the tail of our dog Sam. You had to make your own paintbrushes as well as amusements in those days.
Because it came from a pub I wonder if the wooden thing was part of a game, maybe like solitaire, involving marbles. And now somehow, in a way that may reveal something about my ragbag of a brain, I want to complete my mantelpiece of useless objects with a few special marbles. Gizzard stones. More precisely, Great Auk gizzard stones. This may be the point at which it is customary to write ‘Let me explain!’
I used to wonder at pigeons brevetting about dangerously on the edges of busy roads, until I realised that they were ‘gritting’. That is, picking up small carefully chosen stones that build up on the roadside to store in their gizzards, where they help this tough muscular organ to grind up their food and make it more digestible. Many birds, especially seed eaters, do this too.
Dinosaurs, ancestors of birds, had gizzard stones, called gastroliths by scientists specialising in ‘avian lithophagy’. You can get them on eBay for about a tenner. But if you want Great Auk gizzard stones to grace the mantle-piece you have to go the auk islands off the coast of eastern North America. I can’t think of a better reason to go to North America. I want some.
When we in Europe started plundering the stocks of cod on the Grand Banks off Newfoundland, we also found the auk islands, populated by vast numbers of auks – Razorbills, Guillemots and Great Auks. The fishermen began not to bother to take much food with them for their long voyages, and instead they went ashore on the auk islands and butchered the Great Auks. I’m not sure why they weren’t happy to eat the fish they were catching. Maybe we just can’t resist the chance to exterminate a vulnerably flightless bird when we find one. The fish were below the surface and no-one much noticed that the fisherman were on their way to eliminating something as spectacular in a watery sort of way as the vast herds of buffalo on the Great Plains, or the Passenger Pigeon, once the most numerous bird on the planet. But they did notice that the Great Auk was getting scarce enough to be stuffed and collected, which may have upped the price of stuffed Auks and hastened their extinction. The last birds were seen variously in Iceland and on St Kilda, and the last Great Auks ever seen alive were killed on an Icelandic island in 1850. They have left behind a few stuffed specimens, a few collected eggs, and the word Penguin, (Welsh pen gwyn, white head) which may have been bequeathed to Penguins by the Great Auks when they didn’t need it anymore, all being dead.
Dead in such numbers, where they were butchered on the flattish islands on which they were able to waddle ashore to breed, that there are still areas of soil on some of these islands largely derived from the rotting remains of the discarded body parts of hundreds of thousands, maybe millions, of Great Auks butchered on these islands between about 1500 and the early 1800s. If you sift through this soil you will find small rounded pebbles about the size of marbles, the gizzard stones of Great Auks, left behind long after the gizzards that contained them have tuned to dust.
I’ve got a bit interested in auks, as you can see, and this has taken me on to Guillemots, smaller relatives of the Great Auk which, luckily for them, can fly. I started reading about Guillemots because of an interest in the Great Auk, and because studying the relatives of the Great Auk might help to understand them better. And so I got interested in the ecology of the Guillemot and also in the ways that ecologists think and investigate.
One aspect of Guillemot behaviour is called ‘extra-pair copulation’. I’m hoping to get on soon to the ecology of another seabird, the Shag (Phalacrocorax aristotelis) to see what the ecologists call it then. Guillemots, like humans, go in for lifetime pair bonds, and ecologists have been interested in finding out why Guillemots also go in for extra-pair copulation. The scientific method used by ecologists to investigate this is to formulate hypotheses that might explain the behaviour and then investigate by observation or experiment to test these hypotheses, often perched on a cliff ledge out Newfoundland way as they do so.
One hypothesis was that the male guillemots aren’t very good at recognising their partners and copulate with other females ‘by mistake’. (Guillemots get a bit excited on the breeding ledges by the sight of other birds copulating, leading other pairs of birds to do the same, which may have evolved as a way of synchronising the egg laying, which reduces the impact of predators on eggs and chicks). A likely story, you may think, and in fact it is disproved because males may copulate with another female when their mate is close by. Another hypothesis was that some of the Guillemots were oversexed due to some hormone imbalance or illness, but that seems unlikely since they only copulate with females when they are most likely to be fertile.
The ideas that the ecologist might develop and want to test would tend to be based on Richard Dawkins’ ideas about behaviour having evolved to enable an individual to pass on as many as possible of his or her genes. So you might try to find out if extra-pair copulation was likely to result in fertilisation and hence in passing genes on. This might involve the notion of ‘sperm competition’ – in which rather than the fittest males gaining the females attention and hence passing on his genes, it might be the male with the most vigorous sperm whose genes did best. From the female’s point of view, the fittest guillemot mate to breed with might not be the fittest helpmeet when it came to raising her chick. There are pages of this stuff in Tim Birkhead’s fascinating book, which I recommend below,and you may well also enjoy his inevitable excursion into comparison with human behaviour.
Although it is difficult to find out this kind of sensitive information, some researchers have come to the conclusion that 30% of children born in tower blocks are not the offspring of their mother’s long-term partner. This compares closely with the extra-pair paternity on the guillemot ledges, where the individuals live in similarly convenient close proximity. In the leafier suburbs, the songbirds in the hedges and the humans living in less close proximity in their detached houses share an extra-pair paternity rate of about 10%.
I’m wondering if we could use these scientific methods to look at the behaviour of politicians, or farmers, for example. You might in your study area have a population of farmers all resident in their breeding territories, jealously guarding them against all intruders with their familiar cries of ‘Get off my land’ or ‘Can I help you?’ You would observe them planting seeds, cutting grass, moving animals around and so on. You might then form several possible hypotheses to explain their behaviour, possibly informed by what you overheard them saying or what you read in their farming newspapers. One hypothesis might be that they were looking after the countryside. Another might be that they were feeding the nation. Other possibilities might include supporting their families in a pleasant lifestyle, or maybe making as much money as they possibly can. Money might in fact turn out to be the real crop that they are cultivating. They might be farming because they have always done it and can’t think of anything else to do. They might even be doing what they do for several of these reasons, and after careful observations some of your theories might be supported by the evidence. You might have to take into account external factors making them do things they might not otherwise do. These might include subsidies, or a chemical industry telling them that you can’t grow healthy and nutritious food to feed the nation without putting a lot of poisonous chemicals everywhere. Or a ministry saying a little strip left wild around the field might compensate for all the chemicals used everywhere else. All these variables will actually help you to refine your interpretation of their behaviour.
I wish you happy researching.
I owe a large debt here to the books of Tim Birkhead, in particular ‘Great Auk Islands’ (T & AD Poyser, London 1992) and ‘The Most Perfect Thing’ (Bloomsbury 2016). Also to my brother Andrew whose work on St Kilda has revived my interest in the demise of the Great Auk.