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Rare Birds in Spain

Identification

Spring plumages of Mediterranean and Balearic Shearwaters

by Ricard Gutiérrez

Introduction
Acknowledgements

Introduction 

The identification of Mediterranean (also named Yelkouan) Shearwater Puffinus yelkouan in comparison with its Mediterranean sea counterpart, the Balearic Shearwater (P.mauretanicus) is one of the 'classic' species-pair problems that, despite having been regularly dealt in the birding literature (e.g. Mc Geehan, A. & R.Gutiérrez. 1997a Dark Secrets. Birdwatch, 61: 26-30; Gutiérrez, R. 2004. Identification of Yelkouan, Balearic and Manx Shearwaters. Birding World,17: 111-122 to name a couple of mine) it's still under consideration given for example the existence of the Menorca population which phenotypically is yelkouan like but that it might have some mauretanicus genes (see this Birdguides note for example).

The coasts of Catalonia are one of the few areas in the world where both species can be compared side by side along the year. In the Girona N coast, however, yelkouan (or at least yelkouan-like for the purpose of this note) outnumber the concentrations of mauretanicus, particularly in spring and summer, and concentrations of thousands of those Mediterranean Shearwaters have been reported from Cap de Creus to Palamós in the South of Costa Brava.

In late May 2010 large numbers of Mediterranean Shearwaters were recorded along the area. Those included over a hundred around Roses Bay and over 1.100 birds at Medes Islands (including a few tens of mauretanicus as well) on 20.5 (Ricard Gutiérrez, Albert López, David Caballero, Teresa Montràs) and over three hundred S of Begur cape, towards Palamós on 23.5 (Gerard Dalmau, Guillem Hontangas, Gerard Berengueras, Ricard Gutiérrez, Joan Hontangas, Bruna Roma, Gerard Gutiérrez, Ariadna Gutiérrez, Helena Arbones). The birds were observed in a diversity of lights, from contrasted morning sunny conditions to late evening warmer and yellower sunlight to a completely foggy sea on 23rd of May 2010. This note shows some of the pictures taken those days comparing the results with previous data also from the same wide area.

Since late spring - early summer the plumage of yelkouan becomes increasingly worn, initially distinctive dark grey almost black yelkouan plumage looks dark brown and variably worn according to exposure to sunlight of the different feathers. In these months, the identification of yelkouan becomes always more difficult, since the plumage tones can approach those of mauretanicus which, however, remains structurally more powerful, longer-winged and differently head-shaped.

Interestingly, the fewmauretanicusrecorded in late May 2010 showed a very different moult pattern from most (roughly over 98%) of the yelkouan. Its moult score was higher (more advanced moult stage) compared with yelkouan since all secondaries were in simultaneous growth, something only recorded in a few yelkouan (see photos). It's not clear if those moulting birds could be breeders or non-breeders, as suggested by Gutiérrez (2004), but yelkouan breeding in Menorca by late June 2003 had that score, hence the observed moulting birds were a month ahead of what had been seen in other areas also for mauretanicus (e.g. Mouriño et al 2003).

Also interesting was comparing these mauretanicus with handled birds caught accidentally in a fishing longline hook near Montgrí area, just N of the Medes islands, in May 2008. All examined 11 mauretanicus from 2008 showed a similar growing pattern of secondaries, while an analysis of breeding condition showed that all birds were not actively breeding (see photos below). Also similarly, a yelkouan non-breeding bird released after an intoxication episode produced by sea algae at Roses Bay in June 2007 had also a very visible 'gap' comparing primaries and secondaries, that were in active growth (figure below).

Some of the photos of the 2010 flying birds show darker secondaries. This may have been caused by a different wear stage due to a different feather age or even sun exposure. But in all cases feather length differences are a clear indication of active growth, even more if it was confirmed with in-hand examination.

All in all, these photographs may contribute to support the theory of moulting related to an active or non active breeding condition and the differences between both species in this season.

Puffinus yelkouan

All photos © Ricard Gutiérrez

Puffinus

Puffinus raft (mostly yelkouan). Medes Islands, Girona. 20.5.2010

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010

Pufyel Caldio

2 Puffinus yelkouan & 1 Calonectris diomedea. Off Palamós, Girona. 23.5.2010

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010.

Pufyel

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010

Pufyel

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010. Notice the rounded head shape and typical forehead shape.

Pufyel

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010. A rather dark bird but yet yelkouan.

Pufyel

Puffinus yelkouan. Off Palamós, Girona. 23.5.2010. Notice the old, worn plumage which makes the bird become brower, more mauretanicus-like. But despite stretched wing, notice body shape, front slope, hint of eye-ring and leg length compared with mauretanicus.

Pufyel

2 Puffinus yelkouan. Off Palamós, Girona. 23.5.2010. Left bird show an apparent gap between primaries and outermost secondaries.

Pufyel Puffinus yelkouan. Off Palamós, Girona. 23.5.2010

Pufyel

Puffinus yelkouan. Off Roses, Girona. 20.5.2010 morning

Pufyel

Puffinus yelkouan. Off Roses, Girona. 20.5.2010 morning

Pufyel

Puffinus yelkouan. Off Roses, Girona. 20.5.2010 morning. Non moulting birds

Pufyel

Puffinus yelkouan. Off Roses, Girona. 20.5.2010 morning. No trace of moult apparently seen.

Pufyel Puffinus yelkouan. Medes Islands, Girona. 20.5.2010 evening. Unlike most yelkouan, this showed apparently growing central secondaries, with perhaps older innermost. Compare with bird below.

Pufyel

Puffinus yelkouan. Medes Islands, Girona. 20.5.2010 evening

Puffinus mauretanicus

Puffinus

15 Puffinus yelkouan & 1 P.mauretanicus (bottom right), Medes Islands, Girona. 20.5.2010 evening

Pufmau

P.mauretanicus, Medes Islands, Girona. 20.5.2010 evening. See another photo of this bird below.

Pufmau

P.mauretanicus, Medes Islands, Girona. 20.5.2010 evening. Note old primaries with even broken tips and simultaneously growing secondaries.

In hand birds

Pufmau

P.mauretanicus upperwing, Montgrí coast, Girona. 17.5.2008. In hand examination.Innermost secondaries are growign, three outermost older than the rest but all more new than primaries.

Pufmau

P.mauretanicus underwing, Montgrí coast, Girona. 17.5.2008. In hand examination. Notice abraded primaries compared with growing secondaries.

Pufyel

P.yelkouan upperwing, Aiguamolls de l'Empordà Natural Park, Girona. 15.6.2007. In hand examination. A non-breeding bird showing an active replacement of secondaries, a month later than mauretanicus and yelkouan above.

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Acknowledgements

My warmest thanks to all those who have believed in seabirds & sealife conservation effort in Catalonia. Particularly in this case to Joan Hontangas and his Radi vessel, Albert López and Gemma González and their Projecte Ninam's Dzul Haà vessel, Alex Lorente and colleagues from Medes islands and Montgrí Natural Park and all those who have helped in any way: Cap de Creus Natural Park, Wildlife Service of Generalitat de Catalunya, the family, Armand, Sergi, Emma, Carol, Gerard, Berengueres, Guillem, Bruna, Tere, Àlex, Eva, Jordi, Roca's brothers, Aïda, Santi and all of you that have expressed your interest or support in any way along the years.


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Citation
Gutiérrez, R. 2010.Spring plumages of Mediterranean and Balearic Shearwaters. Rare Birds in Spain. Retrieved from http://www.rarebirdspain.net/arbsi034.htm 



 



Spring plumages of Mediterranean and Balearic Shearwaters

Summary:
Introduction

Puffinus yelkouan

Puffinus mauretanicus

In hand photos

Acknowledgements

Citation
 
 
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30.5.2010