§1010 Ἀπορήσειε δʼ ἄν τις ἴσως πῶς κινοῦνται τέτταρσι σημείοις οἱ ὄρνιθες, ἢ πετόμενοι ἢ πορευόμενοι, ὡς εἰρημένου ὅτι πάντα τὰ ἔναιμα κινεῖται τέτταρσιν.
One might perhaps raise the question of how birds move by four points, whether flying or walking, as though it had been said that all red-blooded animals move by four points.
οὐκ εἴρηται δέ, ἀλλʼ ὅτι οὐ πλείοσιν.
But this was not said; rather, it was said that they move by no more than four.
οὐ μὴν ἀλλʼ οὔτʼ ἂν πέτεσθαι δύναιντο ἀφαιρεθέντων τῶν κώλων οὔτε πορεύεσθαι τῶν πτερύγων ἀφαιρεθεισῶν, ἐπεὶ οὐδʼ ἄνθρωπος βαδίζειν μὴ κινῶν τι τοὺς ὤμους.
Nevertheless, they would not be able to fly if their legs were removed, nor to walk if their wings were removed, since not even a human walks without moving their shoulders to some extent.
ἀλλὰ πάντα γε, καθάπερ εἴρηται, κάμψει καὶ ἐκτάσει ποιεῖται τὴν μεταβολήν·
But all animals, as has been said, perform their change of place by bending and extension; for all advance against what is underlying, up to a certain point, as if against something that yields.
ἅπαντα γὰρ εἰς τὸ ὑποκείμενον μέχρι τινὸς οἷον εἰς ὑπεῖκον προέρχεται, ὥστʼ ἀναγκαῖον, εἰ μὴ καὶ κατʼ ἄλλο μόριον γίνεται ἡ κάμψις, ἀλλʼ ὅθεν γε ἡ ἀρχὴ τοῖς μὲν ὁλοπτέροις τοῦ πτεροῦ, τοῖς δʼ ὄρνισι τῆς πτέρυγος, τοῖς δʼ ἄλλοις τοῦ ἀνάλογον μορίου, καθάπερ τοῖς ἰχθύσι.
Consequently, it is necessary, even if the bending does not occur in some other part, at least to occur at the origin—of the wing for the holoptera, of the wing-feather for birds, and of the corresponding part for the others, such as for fish.
τοῖς δʼ, ὥσπερ οἱ ὄφεις, ἐν ταῖς καμπαῖς τοῦ σώματός ἐστιν ἡ ἀρχὴ τῆς κάμψεως.
For others, such as snakes, the origin of the bending is in the bends of their body.
τὸ δʼ ὀρροπύγιόν ἐστι τοῖς πτηνοῖς πρὸς τὸ κατευθύνειν τὴν πτῆσιν, καθάπερ τὰ πηδάλια τοῖς πλοίοις.
On the other hand, the rump is for flying animals used to steer their flight, just like rudders for ships.
ἀναγκαῖον δὲ καὶ ταῦτα ἐν τῇ προσφύσει κάμπτειν.
And it is necessary for these parts also to bend at their point of attachment.
διόπερ τά τε ὁλόπτερα καὶ τῶν σχιζοπτέρων οἷς τὸ ὀρροπύγιον ἀφυῶς ἔχει πρὸς τὴν εἰρημένην χρῆσιν, οἷον τοῖς τε ταῷς καὶ τοῖς ἀλεκτρυόσι καὶ ὅλως τοῖς μὴ πτητικοῖς, οὐκ εὐθυποροῦσι·
Therefore, both the holoptera and those of the split-winged birds whose rump is naturally unsuited for the aforementioned use—such as peacocks, domestic fowls, and in general non-flying birds—do not fly straight.
τῶν μὲν γὰρ ὁλοπτέρων ἁπλῶς οὐθὲν ἔχει ὀρροπύγιον, ὥστε καθάπερ ἀπήδαλον πλοῖον φέρεται, καὶ ὅπου ἂν τύχῃ ἕκαστον αὐτῶν προσπίπτει, ὁμοίως δὲ τά τε κολεόπτερα, οἷον κάνθαροι καὶ μηλολόνθαι, καὶ τὰ ἀνέλυτρα, οἷον μέλιτται καὶ σφῆκες.
For none of the holoptera have a rump at all, so they are carried along like a rudderless ship, and each of them falls wherever it happens, and likewise both the coleoptera (such as beetles and chafers) and the elytra-less insects (such as bees and wasps).
καὶ τοῖς μὴ πτητικοῖς ἀχρεῖον τὸ ὀρροπύγιόν ἐστιν, οἷον τοῖς τε πορφυρίωσι καὶ ἐρωδιοῖς καὶ πᾶσι τοῖς πλωτοῖς· ἀλλʼ ἀντὶ τοῦ ὀρροπυγίου πέτανται τοὺς πόδας ἀποτείνοντα, καὶ χρῶνται ἀντʼ ὀρροπυγίου τοῖς σκέλεσι πρὸς τὸ κατευθύνειν τὴν πτῆσιν.
And for non-flying birds, the rump is useless, such as for the purple gallinules, herons, and all web-footed waterbirds; instead of the rump, they fly by stretching out their feet, and they use their legs instead of a rump to steer their flight.
βραδεῖα δʼ ἡ πτῆσις τῶν ὁλοπτέρων ἐστὶ καὶ ἀσθενὴς διὰ τὸ μὴ κατὰ λόγον ἔχειν τὴν τῶν πτερῶν φύσιν πρὸς τὸ τοῦ σώματος βάρος, ἀλλὰ τὸ μὲν πολύ, τὰ δὲ μικρὰ καὶ ἀσθενῆ.
The flight of the holoptera is slow and weak because the nature of their wings is not in proportion to the weight of their body, but the body is large while the wings are small and weak.
ὥσπερ ἂν οὖν εἰ ὁλκαδικὸν πλοῖον ἐπιχειροίη κώπαις ποιεῖσθαι τὸν πλοῦν, οὕτω ταῦτα τῇ πτήσει χρῆται.
Just as if, then, a merchant ship should attempt to make its voyage with oars, in this way these insects use their flight.
καὶ ἡ ἀσθένεια δὲ αὐτῶν τε τῶν πτερῶν καὶ ἡ τῆς ἐκφύσεως συμβάλλεταί τι πρὸς τὸ λεχθέν.
And the weakness both of the wings themselves and of their point of growth contributes something to what has been said.
τῶν δʼ ὀρνίθων τῷ μὲν ταῷ τὸ ὀρροπύγιον ὁτὲ μὲν διὰ τὸ μέγεθος ἄχρηστον, ὁτὲ δὲ διὰ τὸ ἀποβάλλειν οὐθὲν ὠφελεῖ.
Among birds, the rump for the peacock is at one time useless because of its size, and at another time, because of shedding, it is of no benefit.
ὑπεναντίως δʼ ἔχουσιν οἱ ὄρνιθες τοῖς ὁλοπτέροις τὴν τῶν πτερῶν φύσιν, μάλιστα δʼ οἱ τάχιστα αὐτῶν πετόμενοι.
On the contrary, birds have the nature of their wings opposite to that of the holoptera, especially those of them that fly fastest.
τοιοῦτοι δʼ οἱ γαμψώνυχες· τούτοις γὰρ ἡ ταχυτὴς τῆς πτήσεως χρήσιμος πρὸς τὸν βίον.
Such are the birds of prey (those with curved talons); for them, the swiftness of flight is useful for their way of life.
ἀκόλουθα δʼ αὐτῶν ἔοικεν εἶναι καὶ τὰ λοιπὰ μόρια τοῦ σώματος πρὸς τὴν ὠκεῖαν κίνησιν, κεφαλὴ μὲν ἁπάντων μικρὰ καὶ αὐχὴν οὐ παχύς, στῆθος δʼ ἰσχυρὸν καὶ ὀξύ, ὀξὺ μὲν πρὸς τὸ εὔτονον εἶναι, καθάπερ ἂν εἰ πλοίου πρώρα λεμβώδους, ἰσχυρὸν δὲ τῇ φύσει τῆς σαρκός, ἵνʼ ἀπωθεῖν τε δύνηται τὸν προσπίπτοντα ἀέρα· καὶ τοῦτο δρᾷ ῥᾳδίως καὶ μὴ μετὰ πόνου· τὰ δʼ ὄπισθεν κοῦφα καὶ συνήκοντα πάλιν εἰς στενόν, ἵνʼ ἐπακολουθῇ τοῖς ἔμπροσθεν, μὴ σύροντα τὸν ἀέρα διὰ τὸ πλάτος.
The other parts of their body also seem to be consistent with rapid movement—head small in all, and neck not thick, chest strong and sharp, sharp in order to be streamline, as if the prow of a light vessel, and strong by the nature of its flesh, so that it can push away the air that collides with it; and this it does easily and without effort; and the parts behind are light and taper again to a narrow point, so that they follow the parts in front, not dragging the air because of their width.