Thursday, April 20, 2017

Spring migration in the Western Mediterranean (I)

This year for Easter I had the great pleasure to participate once again in the spring ringing season in Illa de l'Aire, an small islet south of Menorca, in the Balearic Islands, where the SOM (Menorcan Ornithological Society) has organized the campaign for the last 25 years!! So the first thing I have to write down is a big congrats for all of you, for being such great ringers and very nice friends!

These days' team was composed by Ingela (who got a lot of new-in-hand species!), and Pere Mercadal, a future Menorcan ringer. And of course, the amount of Lilford's Wall Lizards (Podarcis lilfordi lilfordi) that are virtually everywhere in the island!
Islands often hold incredible secrets of evolution of life, as it's the case for instance with the relationship between the Lilford's Wall Lizard and the Dead Horse Arum Lily (Helicodiceros muscivorus). The plant provides juicy fruits for the lizards to eat, that feed mainly on them during summer, and at the same time the seeds get dispersion over the island. The plant is also called "pig's ear" in Catalan for it's shape and texture, and it's full of this 'hair' that trap flies inside. The flower has a characteristic bad smell, for the acumulation of dead flies inside.
Lilford's Wall Lizard population in this island is one of the most dense populations of lizards in the world! And such a density may attract predators, such as Booted Eagles (Aquila pennata), that have learnt to hunt them. And Kestrels (Falco tinnunculus), that might be too keen to visit the island to hunt, and then they are eventually caught on the nets!

The island acts as the very first piece of land that migrants find after the long sea-crossing over the Mediterranean. Even being a rather hostile island, full of pointed rocks and few vegetation, it must look like a great place to spot for them. Some may stay for hours and then jump to Menorca or continue with their travels, other might need several days to have energy to continue, and other might day on the try. Fortunately most of birds apparently succed on their migration journeys.
This Robin was in a rather poor condition, and stayed in the
island for over a week...

Others (such as this Blackcap) will stay shortly, for a day or
just for several hours. Among the few resouces available in
the island, flowers and their nectar are a rather good source
of energy. And also a good pollination for the plants!
We had rather warm and sunny days, almost without wind, and we were lucky enough to have some good migration days. Robins (Erithacus rubecula) were surprisingly the commonest birds, with more than 230 ringed in a single day. Together with several Blackcaps (Sylvia atricapilla)Song Thrushes (Turdus philomelos), Chiffchaffs (Phylloscopus collybita), 1 Meadow Pipit (Anthus pratensis), 2 Dunnocks (Prunella modularis) and 1 Bluethroat (Luscinia svecica) proved the tendency of this year's spring to have some late (mid-April) peaks of presaharan migrants. The two latter species are rather rarely caught in the island in spring!
Meadow Pipit (Anthus pratensis)
Dunnock (Prunella modularis)
Bluethroat (Luscinia svecica)
Willow Warblers (Phylloscopus trochilus) were the second commonest species, and they lead the transaharan migrants passage. Good numbers of Redstarts (Phoenicurus phoenicurus) and still few individuals of species like Pied Flycatcher (Ficedula hypoleuca)Whinchat (Saxicola rubetra)Common Whitethroat (Sylvia communis), Subalpine Warbler (Sylvia cantillans)Nightingale (Luscinia megarhynchos) and Yellow Wagtail (Motacilla flava)Tree Pipits (Anthus trivialis), among other species.
Tree Pipit (Anthus trivialis)
Yellow Wagtail (Motacilla flava)flava subspecies.
Whinchat (Saxicola rubetra)
Whitethroat (Sylvia communis)
Redstart (Phoenicurus phoenicurus)
Common Nightingale (Luscinia megarhynchos)
More interesting transaharan migrants follows:
Wryneck (Jynx torquilla)
Ortolan Bunting (Emberiza hortulana)
Short-toed Lark (Calandrella brachydactyla)
A lot of Hoopoes (Upupa epops)! This season more than 40
 have been ringed already!

Subalpine Warblers (Sylvia cantillans) were caught in few numbers, but with an interesting diversity. We caught up to 4 putative (pending to be accepted by the Spanish Rarities Committee) Eastern Subalpine Warblers (Sylvia cantillans albistriata) and a putative 'Italian' Subalpine Warbler (Sylvia cantillans cantillans). 

4 different Eastern Subalpine Warblers (Sylvia cantillans albistriata), showing tail and
breast patterns. All 2cy (EURING 5). Notice the deep colour restricted to the throat, with
some feathers with white tips. White moustachial stripe wide and well-defined. R5 has a lot
of white, but only when the feather has been replaced!
'Italian' Subalpine Warbler (Sylvia cantillans cantillans), 2cy
(EURING 5) male. The tail pattern is similar to albistriata, with
a lot of white following the racuis on R5. Underparts colouration
has a slightly distinctive deeper area on the throat, with some white
tips, and orangish flanks and belly.
An Iberian Subalpine Warbler (Sylvia cantillans iberiae).
Notice more uniform orangish underparts, and less white
on R5. Some individuals can show white patterns similar
to eastern taxa, and it can even vary in the same individual,
as in this one: usual iberian pattern on one side and a bit
of white following the rachis on the other.
Also 2 males of the recent split Moltoni's Warbler (Sylvia subalpina).
Notice how the breast colour can change drastically in the pictures!,
and it's of course the same bird... In the sun they look quite orangish
(in the picture!!!), but the real colour, salmon-pink, is better shown
in the picture below. Also notice the dark loral area.
Tail pattern of the individual above, with a straight clear cut between
blackish and white in R5, which is likely to be the common pattern
in subalpina.
Two pictures of the second individual, showing the salmon-pink
underparts, a very dark loral area (not always as obvious!), and
very fresh plumage (look at the closed wing in the second picture),
after their usual complete moult in winter.
Talking about Balearic birds, it might be also interesting to show this Balearic Woodchat Shrike (Lanius senator badius).

Adult (EURING 6) female badiusSome females can have a
more similar male-like plumage.
Adult (EURING 6) male.
As you can see, we had a lot of diversity! And Phylloscopus couldn't be an exception:
Phylloscopus species!
from left to right: Common Chiffchaff (P.collybita)Iberian Chiffchaff
(P.ibericus)Willow Warbler (P.trochilus) and Wood Warbler (P.sibilatrix).
Closer picture of the Iberian Chiffchaff...
And a Western Bonelli's Warbler (P.bonelli)!, that was missing
the other day, but was also caught afterwards!
When Sun goes down and Gulls search for a place to stay overnight...

And seabirds, like Scopoli's Shearwaters (Calonectris diomedea) and Storm Petrels (Hydrobates pelagicus), appear around the island, usually delighting with great scenes while they call and display in the dark.

It's also during the night when most of birds caught during the day will continue their travels, and a new bunch of migrants will be brave enough to cross the Mediterranean.

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