A Nose For Navigation

Last time we were together we finished up looking at a dead grasshopper so this week we'll start with a live one. We're very much in grasshopper territory here and this is our local version of the Meadow Grasshopper, Chorthippus bornhalmi. Crickets and grasshoppers are well known for their songs and it is a common myth that they sing by rubbing their legs together. Almost true. Generally speaking crickets chirp by rubbing their wings together whereas grasshoppers rub their wings against their legs. I see that there's an old stone bridge down there crossing a small gully that gets considerably deeper as it heads southwards. Definitely worth investigating methinks.

The gully seems to be running into a bit of a ravine which is absolutely inundated with Giant Cane. Despite its massive height it is, like bamboo, a type of grass. Also, like bamboo, the young shoots are edible and you can eat the boiled rhizomes apparently. I haven't tried it myself and I've never seen any recipes for it (so I'd be inclined to take that information with a bit of caution or maybe even a pinch of salt) but I'll pass it on anyway. It also looks fairly impenetrable but we won't let a little fact like that put off intrepid explorers like us. I'm sure that we can slide our way through somehow.

OK so they were pretty unforgiving but look who's waiting for us; a Common Darter. Only he's not so common, not at this time of year anyway. It's a fairly recent discovery that certain dragonflies migrate, the same as birds do ^[1]. And how do we know that? Because some fool entomologist managed to fit a dozen of them with the world's smallest transmitters and follow them in a light aircraft for 58km over six days. Research is ongoing and I'll put in my fourpenn'orth with this set of seasonal maps which I've put together from iNaturalist. As you can see you'll only find them in Winter around the Mediterranean. By Spring they're up as far north as the Netherlands and in Summer and Autumn they're in Scotland and Denmark.

You may have noticed that these canes are getting thicker and I'm beginning to think that someone should have put an electronic transmitter on me as I'm not sure which is our best route out of here. Meanwhile we have some pretty little Clematis cirrhosa down here which is quite, quite poisonous (see Entrapment In A Virgin's Bower) and some Myrtle berries, Myrtus communis, which are most definitely edible (see Fly Feet And Lizards' Ears). All of which is rather academic at the moment as we seem to be effectively caged in on all sides and we've traced a tortuous and probably unretraceable route to get this far. All is not lost however as I am indebted to Phil Bebbington who sent me this handy little GPS tracker for our travels. As I've been marking our finds as we go along I should at least be able to track our route back by following the trail of breadcrumbs as it were. So, if I just pick the appropriate screen I get a picture of... what appears to be an earthworm in its death throes. Our route has been more circuitous than I thought. Another feature of this little gizmo is that we can combine our current position with satellite images which means, in theory, that we can see our shortest route out. I say 'in theory' because I haven't yet mastered how to do that yet. I can tell you where we are to eight decimal places of latitude and longitude but that's not exactly helpful at this moment. We will have to rely on the old naturalists' trick of escaping from river gullies: proceed in any direction you like so long as it's up.

It never fails and we seem to have emerged on the same side of the gully as we entered which is a bonus. There's a whole flock of feral pigeons sitting on a telephone wire over there and I swear that they're laughing at us. Ignoring the incongruity of a telephone wire stretching over a pinnacle of rock and dangling down into an inaccessible cave (this is Crete and it's best not to dwell on such conundrums if you wish to preserve your sanity for any length of time), the reason the pigeons are laughing is that they don't get lost in cane breaks. Exactly how they manage to navigate long distances is still under investigation but if, like me, you thought that it was all down to reading the Earth's magnetic field and/or following the sun's arc then you'd be wrong. Both are useful as compasses but not much cop if you don't know where you're heading for. Like ourselves in the cane break, without a satellite image to see where we were in relation to the edge of the canes, knowing our latitude and longitude and the direction of north was of no help. You need a map and so do the pigeons. After forty years of research^[2] it would appear that your homing pigeon probably uses olfactory mapping as a primary navigation tool. They know what home smells like and if you take them to a new location they'll sniff their way back. And on that incredible note I think we'll make our way back. Can anyone smell the car?

The Extra Bit

On the subject of navigation I would propose a study of island postmen. Here on Crete the smaller villages have no road names and no house numbers. If, like Phil Bebbington, you are kind enough to send me a piece of equipment that you have finished with and pay extra for parcel tracking then the Post Office will hand over delivery to a courier. This means that it will eventually arrive in the near vicinity of my home, having travelled across Europe in ever decreasing circles, and after a flurry of telephone calls I will retrieve the package from an exasperated man in a little white van from outside the village shop. Pop it in the regular post and my postman will (almost) invariably deliver it to my door a week or two later. How he memorises where everybody lives is a feat worthy of scientific investigation.

Thanks again for the GPS Phil, it really is a most appreciated gift and I will get to grips with combining it with satellite images!

[1] Dragonflies Migrate Like Birds

[2] How Do Homing Pigeons Navigate?

Photographic Bit

Many of you have asked me what photographic equipment I use so for details of aperture settings, shutter speeds etc. my pictures will be on Flickr within a few days and that has all the geeky stuff. Pictures were edited with FastStone Image Viewer and combined with Microsoft Paint.

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LINKS:

Share your nature thoughts, photos and comments on Naturalists (the facebook page that accompanies this blog)

Explore the region with the #CreteNature interactive Hiking and Nature Map

Cretan Flora

Flowers of Crete;

BIRDS OF CRETE

Crete Birding

Greek Butterflies and Moths

Aquaworld Aquarium

Visit Greece (National Government Tourist Office)

The Milonas Gorge

I think that I may have lulled you into a false sense of security last week with all that beauty in Where Three Valleys Meet. Not that this week’s stage of the journey is any less beautiful but it will require a head for heights and nerves of steel in places. You have been warned! Those three mountain streams that were gently carving out valleys have now got together and their combined force has carved through the limestone like a knife through butter and we’re going to try and get through there. If you’re up for it, follow me.

Not surprisingly, as we enter this damp, almost subterranean gloom, we have fungi. The creamy brown jobs running up the length of this fallen tree are of the Crepidotus genus which is based upon the Greek for cracked ear. Many different species have been described in the past but modern phylogenetic analysis has shown that the same species can show different growth forms depending upon where they are growing. Essentially, like us humans, they can look very different but underneath they’re all the same. The gorgeous little yellow fellow is a wax cap of the Hygrocybe genus and these are rather unusual in that recent research has shown that they seem to have a symbiotic relationship with mosses and other bryophytes. As usual we are constantly discovering new ways in which elements of nature are working together.

I think we need to do a bit of climbing here. If you’d like to flip a few rocks I’m just going to shin up this overhanging pine and spy out our route. What have you got there? One grey and one orange woodlouse. Why? I believe that it is down to a genetic variation. The orange one, being more conspicuous, is more likely to be predated and so the grey form predominates. Did you know that the woodlouse is one of the true blue bloods of the animal world? Instead of having rich, red haemoglobin in their blood (see How To Get Blood Out Of A Stone) they have haemocycanin  that  uses copper to bind with oxygen instead of iron and their oxygenated blood is blue... um, you could have just taken my word for it.

We seem to have reached a little shelf where we can sit and catch our breath for a minute. Which is just as well as the next part looks a bit strenuous. The sea squills are just beginning to push their dark green leaves up from their bulbs and we have quite a swathe of little buttercups. We have over twenty species of buttercup on Crete and the distinctive leaves of these tell us that these particular ones are Ranunculus bullatus (subspecies cytheraeus if you want to be really precise). And where we have flowers we now have a beetle. These delightfully furry Tropinota flower chafers will be all over the place in a month or two’s time but this one seems to be taking advantage of an early harvest.

Now for the hairy bit. I did warn you but before we risk life and limb have you noticed the crag martins dancing through the gorge? You normally find them at this altitude and above but this winter I’ve seen them down by the beach. We always think of bird migration as a long distance affair but some birds are mini migrators – just a few kilometres north to south or from higher to lower altitudes.  Rock thrushes and even ravens tend to move down from the mountains in cold weather round here whereas white wagtails move up from the beaches where they bum around in the summer and head for the shelter of the olive groves. If you’re ready we’ll crawl along this little ledge and then scramble our way to the top. My, but it’s a long way down. I’m not sure that your humming the theme from Indiana Jones in my ear is helping.

The Extra Bit

You have to admit that the view from the top was worth the knee-trembling climb. The whole of the lower valley stretched out before us. All we have to do now is find a way to get down there.

I'll be popping back and forth between Crete and Athens over the next few weeks so please bear with me if I'm a bit slow in answering your correspondence. SD

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LINKS:

Naturalists (the facebook page that accompanies this blog)

See detailed pictures at http://www.inaturalist.org/login  (search - people-stevedaniels-observations)

The Nature of Crete  (Flipboard Magazine)

Cretan Flora

Flowers of Crete;

BIRDS OF CRETE

Crete Birding

Greek Butterflies and Moths

Aquaworld Aquarium

Visit Greece (National Government Tourist Office)

Sun, Sex and Sandpipers

Despite the title this is not a travel advertisement. Well, not for humans anyway. I noticed the other day that after an exceptionally high tide one of our brackish lagoons down at Long Beach had considerably raised water levels. As many of the small inland ponds are now drying up I thought we’d go down there today and see who’s about.

Migration Routes across the Mediterranean

And we are not disappointed - no less than seven different bird species, all of which have two things in common. Firstly, they all search for food in shallow waters and secondly they are all passage migrants to the island; that is they stop off at Crete on their way from Africa to their breeding grounds in the north. Although we get birds flying through every Spring I wouldn’t call Crete a migratory hotspot and the reason for this is very simple: crossing the sea is dangerous. Take a look at this handy map I just happen to have in my pocket. Which route would you choose if you were a bird? West from Morocco to Spain or up through the Middle East are undoubtedly the safest  but if you must go up through the middle then Tunisia to Italy is only 125 miles whereas Libya to Crete is 200 miles and then you have to island hop to reach mainland Europe. Very much a fourth choice then. The more perspicacious amongst you will have noticed the parallels to the current wave of human migration in this regard for exactly the same reasons. But back to the birds: up at the top end we have a Little Egret searching the slightly deeper water for the odd passing amphibian whilst along the edges we have from left to right - Little Stint, Little Ringed Plover, Wood Sandpiper, Greenshank and Ruff. That only makes six you say? Take a look at the other end of the lagoon.

Squacco Heron

Now that is what I call a magnificent bird. If you thought that all herons came in black and white then this one definitely has a full colour licence. Quite small as herons go, standing a little under two feet tall, but beautifully marked. Like the others he’s on his way from sub-Saharan Africa to breed further north, quite possibly among the lakes and marshes of the Balkan Peninsula, where he’ll hang out on the edges of other Heron colonies. All this begs the question: why bother with all this migration business at all? It all comes down to 'where’s the best place to raise a family?' If all the birds stayed in Africa, nesting and raising chicks all over the place, then the food supply would soon run out. As the weather heats up just north of the equator the plants begin to wither and die and the insect life drops off. Meanwhile in Europe, Spring is providing a veritable cornucopia and the further north you go the more daylight hours you have to take advantage of this largesse. If you can make it all the way up to the Arctic the days are as long as you want them to be, there’s plenty of space for everyone and far fewer  predators. In short birds migrate because the chances of successfully raising a family are greater out of Africa. Again, the parallels with our own species are obvious with the major difference being that we don’t fly back again in winter. So it seems logical that the best way to stop the mass human migration, and the attendant misery it brings with it, is to make Africa a safer, more productive place in which to raise a family.

The Life of an Emperor Dragonfly

But now for some sex. You may have noticed as we’ve been walking along that the air is alive with massive, metallic blue dragonflies and the surface of the water is full of what appears to be large brown dead insects. They are not corpses in fact but exuvia, the discarded skins of dragonfly larvae (Dragon and Damselflies – collectively the Odonata order of insects – undergo incomplete metamorphosis. See The Arms of Giants).  Like teenagers everywhere, out on the prowl and dressed to kill, they drop their old clothes where they fall. So off they zoom in search of a girl and then indulge in sex in such a bizarre way that you won’t even find it in the Karma Sutra. The male ejaculates prematurely (supply your own teenage allegories if you must), wraps his sperm in a packet and transfers it to a spot somewhere in the region of those two large blue segments in the middle. Having found a female suitably impressed by his dazzling livery he then holds her down by the back of the neck using a special pair of claspers attached to his rear end. She will then swing her own rear end around, in a way that would be the envy of any contortionist, and pick up the packet from his middle. Then she will lay her eggs and fertilise them with the contents of the package while the male hovers nearby fending off any would-be interlopers.

 

European Green Toad

Now, while we’ve been busy with our bit of voyeurism into the sex lives of dragonflies you may have been aware of a high pitched elongated brrrriiiip sound coming from those reeds over there. If we just part them carefully we may find the originator of this distinctive call. Here he is, one of my favourite local amphibians, the European Green Toad. They’re quite often out and about in the daytime during the mating season but prefer to keep under cover in the heat of the sun. Unlike many toads the European Green Toad is quite heat resistant and can tolerate temperatures up to 40 degrees centigrade. As for diet, he doesn’t worry too much about food during the mating season, his mind presumably being on other things, but outside of that he has a peculiar predilection for ants.

A Hoverfly on Rayless Chamomile

That’s the sun and sex bit done with and it’s getting quite hot and steamy down here in this hollow in more ways than one so let’s go and cool off with a bit of refreshing sea breeze. 

Just here on the edge of the beach we have a little hoverfly busy pollinating some Chamomile. No, it hasn’t lost its petals, it grows like that. This is a type of Rayless Chamomile which goes by the scientific name of Anthemis rigida. It’s one of those horrible scientific names that mixes Latin and Greek.  Anthemis is Greek and simply means flowery whereas rigida is Latin and refers to the fact that the stems are rather rigid. Personally I’d prefer a totally Greek Anthemis akamptos which means exactly the same thing but maybe that’s just me. Enough of the pedantry, that water looks tempting enough for a quick dip.

Until next week – happy hunting.

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Thanks to all at Crete Birding this week for their help in sorting out the Sandpipers and their relatives.

LINKS:

Naturalists (the facebook page that accompanies this blog)

http://www.cretanflora.com/ (an invaluable guide to the flora of Crete)

Aquaworld Aquarium (Hersonissos: for Crete’s marine life and reptiles – well worth a visit)

Flowers of Crete;

BIRDS OF CRETE

Visit Greece (National Government Tourist Office)