In my last Nature Table post I gave you the challenge of identifying a feather; I can reveal now that it was a wing feather from a Great Spotted Woodpecker (Dendrocopus major), many of you got this right so I am quite impressed – perhaps it was a bit easy.
Today I am looking at the few skulls I own (I wish I had more but they aren’t easy to come by!) almost all of them are from birds. Skulls are complex structures for the obvious reason that they have a multitude of tasks to perform for the animal; protection and support of the brain, housing the eyes, chewing and ingestion of food/water, housing the nasal and ear cavities – and doing all this without being too heavy for the animal to hold up. Skulls are very telling objects for the naturalist to inspect; they reveal a lot about the animals life history, especially what senses it uses most. Large eye sockets might lead you to conclude that it is a nocturnal creature, the position of its nostrils may indicate the habitat it lives in and in birds particularly their beaks reveal a lot about its food (jaws and teeth do the same in other animals).
This first skull is from a Robin (Erithacus rubecula) and is actually from a bird that my cat rather unfortunately killed in my front garden, I took the body (which was uneaten) and rotted it under a flowerpot. It is truly tiny (about 2cm long) and makes you appreciate how much the feathers make up the apparent bulk of a bird. The actual space in the skull for the brain is remarkably small as the bill and eye sockets take up most of the room; you can see how the weight of the bill is reduced by having those holes in the sides – which double as nasal openings.
This second skull is a Magpies; from the same bird that owned those wing feathers I showed you last time; the differences from the Robin are striking, most noticeable is the thickness and solidity of the beak. The brain cavity also takes up a larger proportion of the skull than in the Robin; nearly a third, otherwise though the overall shape and layout of the skull is very similar to the Robin – showing that despite obvious differences in size and the niches they occupy, their main habitat (being woodland) is probably the same.
This last skull is particularly interesting, I obtained it during a day trip to the island of Skomer off of the Welsh coast; it belongs to a Manx Shearwater (Puffinus puffinus) which has a large breeding colony there. On my walk around that small isle I came across huge numbers of Shearwater body parts in various states of decay littered around the paths, this was the work of Great Black backed gulls which are voracious predators of our coasts. These are most unusual birds, they spend all day on the open ocean looking for shoals of fish then at night they return to their breeding colonies (how do they navigate?!) to feed their chicks that are hidden deep in old rabbit burrows. The shape and structure of this skull is rather different to the previous two, which gives away that it lives in a completely different habitat. The hooked tip of the bill is used for grasping fish from the waters surface (I say fish, but they probably take anything from crabs to jellyfish or whale blubber), the nostrils are small and the whole head is quite elongated; helpful for diving and streamlined gliding over the sea waves. Notice particularly the position of the eye sockets; they are much more to the top of the head than the Magpies, this is probably because of their need to see above them for danger from gulls or Skuas when they are flying low over the water.
This weeks mystery item is these two jaw bones, the small upper one is 2.5cm long and the lower is 3.5cm. Missing a few teeth but hopefully a few of you can give an educated guess, seeing as it’s a bit difficult I’ll give points if you are close to the truth.