Arxius mensuals: Novembre de 2014

Black Stork wintering in Catalonia?

Since 20 years ago to see White Storks wintering in the whole of Spain has become a commonview. They feed on wetlands, open fields and rivers but also, and many times mostly, in trash centres. Here they feed on a variety of items with a big short term success but with an uncertain success in the medium and long terms.

Black Storks have a really different behavious as they are little likely to be found in trash centres and similars. They mainly feed on fish and frogs to be found along rivers and streams, mainly inside or nearly forested areas. Black Storks, as many Whites are migratory birds, arriving to European nesting sites in April and leaving the continent in September and October.

In Catalonia Black Storks are only migratory birds as no breeding population is settle in the country. Nevertheless in the past five years some birds appear as soon as January and February. They are supposed to arrive from Southern Spain, where little numbers of them remain in winter.

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Black Stork white Whites at the roof of the Lleida waste centre. Note the longer, more pointed bill when comparing with White Storks.

 

This winter seems to be different, thought. One Black Stork has been seen around the Lleida trash centre during the las 40 days. It feeds directly in the trash along with White Storks as well as look for food in the fields around. The last sight of this bird (an adult) was on 23th November, in one of our tours.

That day we saw the bird resting along with White Storks at the roof of the Lleida trash centre main building. After 20 minutes the bird was going on ground to feed on trash along with several White Storks, Red Kites, Jackdaws and other.

This is of interest both because it seems to become probably the first Black Stork wintering in Catalonia and because of the mymethic behaviour of White Storks. If this is a punctual case or a new tendency in this species it is to be see in the future.

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Black Stork in a crowed image with White Storks. Note smaller size and more horizontal position of the body when resting.

 

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Yellow-browed Warbler (Phylloscopus inornatus) influx in Catalonia (North-East Spain)

Yellow-browed Warbler (Phylloscopus inornatus) is, by far, the commonest Siberian bird visiting West Europe. Within the last two decades an average of over 100 of them have been seen every autumn in both the UK and France. In fact, this species is no longer to be considered a rarity in these countries but a scarce migratory bird.

Yellow-browed Warblers breed in Central and East Siberia, where it prefers the huge boreal forests known as taiga. During migration it is likely to appear in small patches of trees, prefering decidous forest although it is also to be found in coniferous forests.

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Yellow-browed Warblers (Phyllocopus inornatus) present a marked facial pattern ressembling Goldcrest and it is slightly smaller than Chiffchaffs.

This 2014 a large influx of YBs have been reported in France, Spain and even Morocco. In Catalonia, over 25 of them have been spotted in different localities, which it mades this year as the best for this warbler in the country. Despite most of the sights have been made along the coast or close to some birds have been found in mixed forest in inland wetlands.

Are we seeing a change in the migratory habits of this bird? Yellow-browned Warblers winters in South and South-East Asia. But it seems to be clear that at least a small portion of its population is not going to Asia for winter. An explanation to this aparently change of migratory habits is the increase of its breeding population at the West of the Urals. It was considered to be fairly scarce in the 60s but about 45.000 pairs were nesting in the area in the 90s.

But, where do these birds go? Do they winter in somewhere in South-West Europe? Or do they winter in some of the countries facing the Guinea Gulf? These questions are still without any answer. What it seems to be sure is that this bird becomes more and more common every autumn in Western Europe. Let see if this is a new trend!