Why do some birds hop and others walk? Essex, Sussex, Middlesex – but what about Nossex?

Why do some birds hop, others walk or run, and others (such as magpies) do both?

According to my late Dad, it's all to do with the size of the bird's brain. Small ones, such as finches and wrens, do not have enough grey matter to allow them to walk, so can only hop. Larger-brained ones can do either.

Brian Brown, Aberdeen

It is said that birds that habitually perch in trees hop, because it is not practicable to walk from twig to twig, while those that spend much of their time feeding on the ground walk. However, this is too simplistic; it also depends to a degree on the size and morphology of the bird in question, and on what is most energy-efficient and practicable: sparrows hop, and perch in trees; vultures also hop, ­although their lifestyle does not ­constrain them to living in trees.

Energy conservation is much more critical to birds than it is to humans. Well-fed humans could live for weeks without eating; a bird has to feed ­almost daily, making an effective feeding routine essential. Flying uses up energy at 10 times the rate of walking or hopping, so ground-feeding birds avoid flying if foraging over short distances – this is why feral ­pigeons in towns walk out of your way, and only fly if rushed at.

There is also a difference in the amount of energy used in hopping and walking. Magpies walk when they only need to move very short ­distances and hop when the distance is somewhat greater, because they have a clumsy gait and get there far more quickly than by walking. It might expend more ­energy, but the bird gets there quicker: ­natural ­selection has ensured birds know ­instinctively what to do for the best.

Birds that spend most of their lives on the ground always walk, it being the most energy-efficient way of getting around. But they also are able to do this freely – wagtails, for instance, which always walk, have relatively long legs and a freedom of movement that a sparrow cannot match.

Terence Hollingworth, Blagnac, France

To get to the other side.

Vic Smith, Ickenham, Uxbridge

What is the origin of the loyal toast – the Queen – at formal dinners? And what is a loyal, ie patriotic, ­republican to do?

The Jacobites did not believe that William III and his successors held power constitutionally, hence their ­efforts to avoid drinking a loyal toast (N&Q, 20 January). The current queen, however, is the constitutional head of state and republicans ought to recognise this by drinking to her health at formal dinners. Working towards ­constitutional change is an entirely separate matter.

Keith Stapylton, Bracknell, Berks

A friend of mine had the perfect answer – but it only works if you come from Lancashire. When everyone else intoned "the Queen", he toasted "the Duke of Lancaster" – which, of course, the monarch is – and that seemed to solve the problem. A propos of that, is there any truth in the old story about naval ­officers ­toasting "sweethearts and wives" when dining at sea on a ­Saturday, to which the youngest ­member of the wardroom ­replies, "and may they never meet!"

Colin Marsh, Leicester

A colleague, surprised to be ­leading us in very formal ­circumstances, stood to propose: "Comrades, 'the Queen'."

Denis Mongon, Widdington, Essex

Middlesex, Wessex, Sussex, Essex – what happened to Nossex?

Please, We're British.

Sally Dignan, Frome, Somerset

Nossex? The population died out.

Erich Hediger, Cottingham, E Yorks

While people are thinking about that, does anybody know what happened to South Finchley? There's North Finchley, East Finchley, West Finchley and Finchley Central – but no South Finchley.

Lawrence Greenberg, London N14

Nossex became Norfolk.

Mike Eatough, Cheltenham

I can do passable dogs, pigs, lions, snakes etc for the children but what noise does a giraffe make?

In our house, giraffes always used to say "hello down there".

Janet Ayres, Stockport, Ches

In reply to Angus Doulton's question about what noise dinosaurs make (N&Q, 20 January), your guess is as good as anyone's. If a dinosaur makes a noise in a forest, you couldn't hear it above the sound of falling trees.

Ed Saul, Canterbury, Kent

Any answers?

Taking inflation into account, what film is the biggest seller at the box-office?

John Johnson, Bedale, N Yorks

Vincent van Gogh and his brother Théo were Dutch, so why did they normally write to each other in French?

Tom Maxwell, London SW19

Why do I eat my biscuits chocolate side up?

Suzanne Asher, Barcelona, Spain

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