Thursday, May 28, 2015

A special island

It has passed almost a whole spring and I've been posting almost nothing, but that shouldn't indicate a lack of activity. In fact, I've been probably too busy to stop and write... Summer is coming, I'm sure I'll find time to summarise the most interesting stuff.

One of the most exciting things I've been involved this spring: another visit to Illa de l'Aire, a small island south of Menorca (Balearic Islands) where a lot of friends from SOM (the local birding organisation) are carrying a spring ringing campaign. I've been there other times, just look for the label Illa de l'Aire.
  This season has been rarely low in the number of captures. Some theories are already in our heads, but we'll wait to analyse the data properly. It seems that the easterly winds could had drifted birds away, straight to the continent; and also Raül and Santi (the main ringers of the campaign) awared me about the very good body condition in most of species: high fat and muscle scores, high weights...
The island is probably the first part of land many migrants see after crossing the Mediterranean from Algerian coast. The place works specially good for birds who really need to stop, and those that are in better condition usually keep on flying a little bit more. Following that, we should be happy if the number of captures is low, but many migrants are theoretically crossing the sea more succesfully.

The number of Willow Warblers (Phylloscopus trochilus) 
trapped is almost 2000 below the average this season.

During my four days of stay, we got a mean of 20 birds/day, but we trapped a very nice mixture of species. I'll post about some topics.

Ageing Northern Wheatears (Oenanthe oenanthe)
Both postjuvenile and prenuptial moults are quite restricted, involving just a few inner GCs. Here three second-year birds:
Second-year (EURING 5) female. GC10 postjuvenile.
Second-year (EURING 5) male. GC10 postjuvenile, GC9
and 3 Median coverts are prenuptial.
Second-year (EURING 5) male. GC10 postjuvenile,
GC9 prenuptial.

Sexing Pied Flycatcher (Ficedula hypoleuca)
Some second-year males are specially difficult to sex. Look at the second bird below; a male with "female-like" appearence. White patches visible in forehead, black uppertail coverts and blackish prenuptial greater coverts. It has more white in greater coverts and tertials than a typical female, but still less than is expected in a 2nd year male.

Second-year (EURING 5) male.
Second-year (EURING 5) male, "female-like".

Moltoni's Warbler (Sylvia subalpina)
We trapped this nice male. Some 1st winters undergo a complete prenuptial moult, so we age this bird as EURING 4. Apart from the bluish grey in upperparts, salmon-pink underparts and dark lores, the plumage is very fresh because of the moult strategy.

There are a lot of other very nice things in the island apart from birds. For example, Lilford's Wall Lizard (Podarcis lilfordi lilfordi), always very curious and friendly, and the nice sunsets.

Special thanks to everybody I've met this season: Rafel, Nara, JJ, Raül, Santi, Sergi, Lola, Gabi...
I'll be back soon!!

Wednesday, April 29, 2015

'Orange-bellied' Barn Swallows

Whilst ringing some Barn Swallows (Hirundo rustica) in spring migration, some birds with orangish underparts attracted my attention. It's not unusual, but always 'special'. I wanted to say some things about them.

Following the genetic analyses by Dor et al. 2010, European-Mediterranean subspecies (H.r.rustica, H.r.transitiva and H.r.savignii) are part of a clade with no clear differences between subspecies. Actually, the study, together with Zink et al. 2006, suggests that the Barn Swallow could be treated as monophyletic (at least inside the European-Mediterranean clade), and states that the morphological differences between populations can be explained as a radiation in the early stages of differentation and potential later speciation. Following these findings, it seems likely that an African ancestor established the first population in Egypt, and then it expanded to Middle East and later on to Europe.

East-Mediterranean subspecies, transitiva and savignii, are well known to have orangish underparts. Typically, some orange-bellied Swallows appear in Europe, always provoking some discussion about their subspecific identification.

'Orange-bellied' Barn Swallow (Hirundo rustica cf. transitiva/savignii)
in Lanzarote (Canary Islands), April 2011. Photos by Juan Sagardía
First of all, it's important to note that both savignii and transitiva are sedentary, while, as is well-known, rustica is a tran-Saharan migrant. That considerably reduces the chances of spotting an eastern Mediterranean subspecies outside of its breeding range, and, in fact, it makes them really rare in western Europe.

Appearently, no morphological differences appear to be discriminant to subspecies identification. At least, I haven't found any difference mentioned in bibliography apart from tail streams lenght, which is also a sex-related character (Vortman et al. 2011); savignii has shorter tails than the other subspecies, but this would not be enough to identify one.

As I was saying, the 'main' difference between these three subspecies is ventral colouration. While most of European rustica shows whitish underparts, Israeli transitiva are orangish, and Egyptian savignii are even darker, almost chestnut in some individuals.H.r.savignii is, on average, slightly smaller (Svensson 1992), though Cramp et al. (1988) found wing lenght range 113-125 (n=21), which overlaps considerably with the lower end of measurements for rustica.

Some differences in ventral coloration in H.r.rustica, specially in undertail coverts.
Also, from left to right, appreciate the more 'orangish lines' in underparts.

Below, a bird with all underparts orangish. The bird was trapped on 14th April 2015
 in central Catalonia (NE Iberian Peninsula). The light is a bit different, I don't know
why blogger made it lighter, but you can imagine the real colouration anyway.

Both tail streamers lenght and ventral colouration have been proved to be sexual indicators for this species (Vortman et al. 2013). Thus, apart from sex-related differences in this characters, we'll find even more variation due to sexual quality. So, males with longer tails and darker underparts will be 'more attractive' to females rather than other individuals.

Another study (Saino et al. 2013) points out the relation between melanin-based colouration and viability in Barn Swallows, which also supports the idea of orangish Swallows having higher fitness, specially (and more obviously) in the nominate subspecies.

After that, and in my opinion, both transitiva and savignii are not recognisable outside their ranges (at least without proper haplotype analysis -and sometimes this is not enough). So, the regular claims of orange-bellied Barn Swallows in Europe and NW Africa should be taken to be 'high quality' birds.

Indeed, although I have trapped a very few individuals, almost all orange-bellied birds I've trapped were males. Some other were intermidiate in measurements but and I haven't found any orangish birds safely sexed as a female (sexing according to Svensson 1992; tail fork in female up to 57 mm, male > 58 mm; I usually use 60 to avoid extreme females). Additionally, most orangish males I've trapped also had quite long tail streamers, and they were big too (wing lenght usually > 125 mm).

Another 'orange' individual, trapped on 13/04/2015 in central Catalonia.
Although light is very different, this bird was a bit less orangish than
the one on 14/04/2015.

To Bernat Ferrer and Lídia Giménez for their help in the field, and for their interest, that inspired this post. Many thanks also to Stephen Menzie, who revised the text, and to Juan Sagardía for allowing me to use his pictures of the Canary Islands bird.

Cramp, S. (Ed.) (1988). Handbook of Birds of Europe, the Middle East and North Africa. Volume V. Oxford University Press, Oxford.
Dor, R., Safran, R.J., Vortman, Y., Lotem, A., McGowan, A., Evans, M.R., Lovette, I.J. (2012). Population Genetics and Morphological Comparisons of Migratory European (Hirundo rustica rustica) and Sedentary East-Mediterranean (Hirundo rustica transitiva) Barn Swallows. Journal of Heredity 103 (1): 55-63.
Dor, R., Safran, R.J., Sheldon, F.H., Winkler, D.W., Lovette, I.J. (2010). Phylogeny of the genus Hirundo and the Barn Swallow subspecies comnplex. Molecular Phylogenetics and Evolution 56: 409-418.
Saino, N., Romano, M., Rubolini, D., Teplitsky, C., Ambrosini, R., Caprioli, M., Canova, L., Wakamatsu, K. (2013). Sexual Dimorphism in Melanin Pigmentation, Feather Coloration and Its Heritability in the Barn Swallow (Hirundo rustica). Plos One, volume 8, issue 2 (February 2013).
Saino, N., Romano, M., Rubolini, D., Ambrosini, R., Caprioli, M., Milzani, A., Costanzo, A., Colombo, G., Canova, L., Wakamatsu, K. (2013)Viability Is Associated with Melanin-Based Coloration in the Barn Swallow (Hirundo rustica). Plos One, volume 8, issue 4 (April 2013).  
Svensson, L. (1992). Identification Guide to European Passerines. Fourth Edition. Lars Svensson, Stockholm.
Vortman, Y., Lotem, A., Dor, R., Lovette, I., Safran, R.J. (2013). Multiple Sexual Signals and Behavioral Reproductive Isolation in a Diverging Population. The American Naturalist, vol. 182, no. 4 (October 2013), 514-523.
Vortman, Y., Lotem, A., Dor, R., Lovette, I., Safran, R.J. (2011)The sexual signals of the East-Mediterranean barn swallow: a different swallow tale. Behavioral Ecology 22: 1344 - 1352.

Monday, March 30, 2015

I'ts March!

In case you didn't know... :P

March is always a great month because of the first arrivals of many migrant species. Some, as Swallows and many waders, already appear on late February, but March is always better for them.

This situation, the beggining of migration, always produce me some sort of ecstasy that will persist until June. Migration is ON. You may know what I mean if you're birder too. That feeling that almost anything can be flying over you at any time...

I started the month in the Ebro Delta, with Josep, Marina and Xavi, looking for the Brown Shrike (Lanius cristatus) that has wintered there. A very nice bird that we wanted to see... you'll find more information about the finding and everything here.

To be honest, the 'twitch' was nice, but the rest of the day, starting to feel this migration sensations I was talking about, was so much better. We ended up the day in the northen part of the Delta, seeing how almost a hundred Flamingos (Phoenicopterus roseus) were taking off and going away, migrating along the coast...

Firsts Wood Sandpipers (Tringa glareola) of the year too

Also, the beach was full of Chiffchaffs (Phylloscopus collybita), and hundreds of White Wagtails (Motacilla alba) were around too...

Back to my area, inland, migration seems to not be as nice. Anyway, I've seen some nice species here too! The first one, this Jack Snipe (Lymnocryptes minimus) appeared in one of the typical places for them. It's quite a scarce but anual species here.

In the same place, days later, 13 Garganeys (Anas querquedula) spent one day to rest. It's a scarce migrant in this part of Catalonia, so more than 10 birds is always a very nice event!

Ringing in my local patch, I trap the biggest numbers of Serins (Serinus serinus) and Great Tits (Parus major) during this month, because of they are actively displaying.

Serin (Serimus serinus). Second-year (EURING 5) male
Great Tit (Parus major), with some sort of melanistic aberration
That day. the first Redstart (Phoenicurus phoenicurus) of the season, an adult male as it 'should' be, appeared. It's a quite confident bird, and it already has been one week here...

 It was impossible to get that Redstart, but at least I trapped another one. You'll see the other was an adult, and this one was a second-year.

With 7 old GCs
I got my first Willow warbler (Phylloscopus trochilus) for the season, too!

As I was saying, while I was taking photos of the Redstart the first day, the thing I probably like the most about migration is the unpredictability. So, suddenly, a flock of 93 Cranes (Grus grus) -quite scarce here, too- were flying over me. Followed by my first Egyptian Vulture (Neophron percnopterus) and Booted Eagle (Aquila pennata)...

Short-toed Eagles (Circaetus gallicus) is probably the commonest raptor in my area during this month. I don't live in a very nice place for raptors, so 30 Circaetus in one morning was the best number I got so far.
Alpine Swifts (Apus melba) are also ery common these days,
with flocks of hundreds almost everywhere
Better things were still waiting to come. 2 Shelducks (Tadorna tadorna) stopped in the same place were we saw the querquedulas days ago. This is an actual rarity in this area, being only the fourth record ever (1 bird in 1978, 2 together in 1979, 1 in 2013).

As last year, I started a 'weekend ringing campaign' in l'Aiguamoll de la Sala. where I trapped some nice birds.
Bluethroat (Luscinia svecica) was one of the first birds I got in the first day:

Numbers of Chiffchaffs and Blackcaps (Sylvia atricapilla) were a bit low, but I trapped two very nice birds. Actually, I had never (!) handled any of both species, so...

This Mistle Thrush (Turdus viscivorus) is an adult. There's no moult limit in the wing, and GC's pattern, with the buffish outer fringes, and the reduced spot on the tip are also good for adult.

The white in underwing was surprisingly bright!
It reflects sunlight a lot!
If somebody had told me I would trap my first Crag Martin (Ptyonoprogne rupestris) in a reedbed, I think I wouldn't believe it, A small flock (about 20 birds), together with Barn Swallows (Hirundo rustica), came into the pool to drink some water. They were flying so low, almost touching the upper part of the nets... and this one finally was trapped in!

In Catalan we say la primavera la sang altera, which is something like "spring alters the blood". As I was saying before with the Serins and Great Tits, this male Lesser Spotted Woodpecker (Dendrocopos minor) was also quite agitated, and decided to jump into one of the nets!