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)

Dawn By The Riverside

Kingfisher

One of the good things about the longer nights in winter is that you don’t have to get up at an unearthly hour to be set up and waiting for the dawn chorus. This week I thought we’d take the car and park up by the little river which enters the sea just to the east of Ierapetra. Surprisingly a car makes a very good hide and as long as you’re in an area where birds are used to cars (almost everywhere) they ignore them.

We’ll go and have a look at the sea later where I expect we’ll find our old friend the kingfisher out on the rocks slyly eyeing the waters below for an unwary shoal of small fish.

Giant Cane

Meanwhile we’ll settle ourselves here under the bridge and wait for the light. Grab one of those canes will you and prop it up overhanging the water. It never hurts to put a convenient perch for dragonflies in a good spot for the camera. This is Giant Cane, by the way, and can grow to thirty feet or more. It’s in flower at the moment but those attractive, golden sprays are pretty much sterile in the seed department. You can see its main method of propagation just here in front of you; a stem falls into the water and new shoots appear at the nodes. It’s a pretty useful plant, being used for everything from construction to basket weaving and medicinally for the treatment of dropsy (oedema). Incidentally if you play the oboe then this is what you are sticking in your mouth each time you blow; Giant Cane is also the main source of reeds for woodwind instruments.

Grey Wagtail

The light is coming up and the sparrows and the hooded crows are starting to arrive and here comes one of my favourite winter visitors, the Grey Wagtail. He usually visits about this time of year and stays until March, bobbing up and down like a demented clockwork toy anywhere where there’s a bit of shallow water. He’s looking for insects of course which is his main food source but he’s not beyond taking the odd tadpole or two or even a small fish if one happens to chance by. I see he’s been joined by another bobber, a black redstart (which you will recall we met last week in Red Autumn). Although they both share this tail wagging habit they are not closely related; the Wagtails and Pipits are from the Motacillidae family whereas the Redstarts are from the Muscicapidae family along with the Flycatchers, Chats, Wheatears and Robins.

I don’t know about you but I’m getting a bit stiff now so let’s go and have a look at the surface of the water and see what insects we can find. If you pass me that pipette from the bag we’ll take a sample of water from the bottom and look at it under the microscope when we get back.

Termite alate

Now this is interesting and not instantly recognizable for what it is, which is a termite.  You don’t often think of them as winged insects but this is an alate; (which simply means winged form) and aletes are destined to become the Kings and Queens of the colony. The other insects that have alates are the ants but termites and ants are not related (even though termites are called white ants in many places).  Termites are in fact more closely related to cockroaches in the insect order Blattodea. The reason I find this discovery of ours particularly interesting is that, according to Fauna Europea, termites are absent from Crete which is not surprising as they’re  more associated with tropical and subtropical regions. As I’ve said before (see Phenomenal Phenology) south east Crete is getting hotter. More evidence of climate change perhaps?

Mediterranean Coastal Snail

While we’re out of the car let’s have a look along the bank and see what else is about. Here’s a gorgeous little fellow having his breakfast. There are two snails locally which look very similar; the Chocolate-banded Snail (Eobania vermiculata) and the Mediterranean Coastal Snail (Theba pisana). They both have these chocolate brown stripes at the base whereas the rest of the shell can be quite variable. The main clue is in the size. This one is a Mediterranean Coastal Snail which has a width of around 15mm in this area whereas the Chocolate-banded Snail is around twice as big at 22-32mm. Sometimes the Coastal gives you an extra clue by having a blue-grey whorl at the apex which the Chocolate –banded deems a bit too flash and will never be seen wearing.

We’ve been out for about three hours now so I think it’s time to go back and make a whacking great kedgeree for breakfast and then we’ll put that water sample under the microscope and see who’s living at the bottom of our river. I think I’ve got some seaweed in the fridge that will add a bit of oomph to the kedgeree. You haven’t tried kedgeree with seaweed before? You haven’t lived.

Ostracod or Seed Shrimp

That’s better, you can’t do microscopy on an empty stomach. Right, where did you put that pipette? Just mount a drop up on the slide so…  adjust the focus… and hello, a freshwater mussel I think. [But I think wrong. I am reliably informed that it is an Ostracod or Seed Shrimp. Having found the specimen in freshwater it most likely belongs to the order Podacopida]
Mussels are molluscs of course, like the snail we saw earlier, but there are several Classes of mollusc. Mussels are Bivalves because they have two valves (or shells as we commonly call them – a somewhat confusing use of the word valve) whereas the Mediterranean Coastal Snail is a Gastropod which means stomach foot. Marine gastropods tend to rasp seaweeds from rocks and terrestrial gastropods go for more conventional chewing like you and me. Seed Shrimps, on the other hand, are gulpers. Something swims by, the Seed Shrimp gets all excited, the valves open and in goes the prey. There he goes look, just press the Video Link and you can see it on your screen (he does this twice after 10 seconds and 45 seconds). Aren’t microscopes wonderful? That chap can’t be any more than a third of a millimetre long.

I don’t think we can top that this week so we’ll call it a day. Just a quick hello to everyone in Scandinavia – nice to have you back. (They’ve been enjoying the 24 hour daylight throughout the summer and now that the dark days are here they’re coming back to the blog – you see I know where you all live). Tell me, how do bats get on in Scandinavia? I’ve never thought about this before. Do they aestivate during the summer and then go hyperactive in the winter?

Now if only I could get rid of this ear-worm. Ever since we started out I’ve had the song “Down by the Riverside” going over and over in my brain with ‘Down’ replaced by ‘Dawn’ Hence the blog title. All the best and happy hunting until next week.

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·         From: Pest Control Technology magazine Mon 17^th November 2014

·         Termites have been the No. 1 structural pest in the United States for longer than most can remember, yet at a recent one-day conference organized by PestBusiness.com and held in Paris, France, it was made clear to the delegates that this is now a real threat facing Europe. Seventy-five percent of the market is in France, but Spain and Italy are fast developing and there are soon likely to be significant additional markets in countries such as Greece and Turkey.

http://www.pctonline.com/Paris-termites-conference.aspx

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Special thanks this week to all at the EntomologyGroup on Facebook with whom I had a long conversation about termites (including an offer to have some cooked for me in Uganda which I was sorely tempted to take up).
And also to invertzoo for identifying the "mussel" as an Ostracod or Seed Shrimp.

LINKS:

Naturalists (the facebook page that accompanies this blog)

Flowers of Crete;

BIRDS OF CRETE

Crete Birding

Greek Butterflies and Moths

AquaworldAquarium

Visit Greece (National Government Tourist Office)