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Tuesday, 5 May 2015

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)


 


4 comments:

  1. THIS week´s text and images are to me personally just perfect. Facts flow fine and humour rightly abound. Do not tell Steve, that he writes an excellent book without knowing it himself.

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  2. Interesting as ever, and so bang on right re the similarities to human plight in Africa. X

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  3. Texte hyper intéressant, superbe observation !

    ReplyDelete