Breeding birds in Europe which follow national borders (1 Viewer)

[jurek]

I recently looked that the maps of the splendid EBBA2 atlas, and distribution of many birds exactly follows national borders. Not necessary borders which follow some geographical barrier.

• Eagle Owl: present everywhere, practically 100% in Germany, Czechia, Slovakia, but stops at borders of Poland and Italy. Breeds everywhere in Finland, but stops at the border of Russia and becomes rare in Sweden. Everywhere in Bulgaria but stops at the border of Romania.
• Hoopoe: present in France, Czechia, Poland but stops at the border of Belgium, Netherlands and West Germany. Former East Germany is in.
• Great White Egret - scarce, but found everywhere in Hungary. Then everywhere in a belt of: Ukraine, Belarus and Baltic States where it reaches far North, but avoids Romania, Poland and Russia.
• Oystercatcher: everywhere in Britain and Benelux and Denmark, but in ireland, France, Germany and Norway restricted to the coast.

You can easily find more examples. I guess it is partially observers error (people fill commoner species but not rarer ones) and partially land use. Any thoughts?

 

[opisska]

Hoopoe is really rare breeder in the Czech Republic, I am quite surprised how full the map is, but it's also or just "possible", maybe there's a difference in methodology at the border? Eagle Owl isn't actually a border, but it ends where the mountains end an the flat part of Poland starts, right? Egret also goes a bit into Slovakia and then stops as the Panonian plain ends and hills start? I think in general a lot of this can be explained by terrain, it just doesn't have enough resolution to see it doesn't exactly follow borders.

 

[dantheman]

Hoopoe is really rare breeder in the Czech Republic, I am quite surprised how full the map is, but it's also or just "possible", maybe there's a difference in methodology at the border? Eagle Owl isn't actually a border, but it ends where the mountains end an the flat part of Poland starts, right? Egret also goes a bit into Slovakia and then stops as the Panonian plain ends and hills start? I think in general a lot of this can be explained by terrain, it just doesn't have enough resolution to see it doesn't exactly follow borders.

And borders often follow terrain/features by default/history ...

A lot of birds stop just as they get to Britain ... ;-)

 

[jurek]

Hoopoe is really rare breeder in the Czech Republic, I am quite surprised how full the map is, but it's also or just "possible", maybe there's a difference in methodology at the border? Eagle Owl isn't actually a border, but it ends where the mountains end an the flat part of Poland starts, right? Egret also goes a bit into Slovakia and then stops as the Panonian plain ends and hills start? I think in general a lot of this can be explained by terrain, it just doesn't have enough resolution to see it doesn't exactly follow borders.

Resolution of 50x50 km makes it difficult to see, but it looks like both species stop at those squares which cross the national borders. Further north, Eagle Owls occur on almost all lowland Germany, but are scarce in lowland Poland. If there was simply a habitat change, line coastline of seabirds or mountains for alpine birds, it would not be that interesting.

 

[Ted Y.]

Resolution of 50x50 km makes it difficult to see,

If so, why speculate it is a yey or a nay? Is just undetermined.
Here is my speculation: birds do not understand Schengen Area. Just a joke.

 

[Ted Y.]

Great White Egret - scarce, but found everywhere in Hungary. Then everywhere in a belt of: Ukraine, Belarus and Baltic States where it reaches far North, but avoids Romania, Poland and Russia.

Not even in the Danube Delta? Look here!

And here, a EBBA2 map proving the last phrase is wrong:

European Breeding Bird Atlas

The European Breeding Bird Atlas is one of the most ambitious biodiversity mapping projects ever done. A total of 596 breeding bird species in Europe. A collaboration across political borders strengthening a network of 120,000 people and organisations who worked together in one of the biggest...

ebba2.info

Birds restricted by political frontiers? Something smells...

 

[Alexander Stöhr]

Hello Jurek,

I dont know the situation in Poland, but Eagle Owl has been succesfully reintroduced in many parts of Germany, after they had gone nearly extinct partly because of human pursuits. Population is going well after much conservation efforts and (presumable) habitation of Eagle Owls to urban/city environments.

I agree with you and all, that this interesting question is best discussed with each species seperatly. Please note, that the choosen resolution of 50x50 km squares and information how common or scarce a species is, makes interpretation further difficult. For example Hopooe is in the parts of NE-Germany I know, a spezialised habitat and a rare species. Yes, its slightly more common in the Fiener Bruch and I found this one: Wiedehopf | Startseite | LfU
Further sign imo, that its good to split the discussion into different species and yes, I am far for an expert in this topic.

 

[Andrew Whitehouse]

A somewhat related example, with a clear explanation:

Vultures avoid Portugal because of carrion ban

Portugal's policy of destroying animal carcasses is endangering its vulture population.

www.bbc.co.uk

 

[Ted Y.]

A somewhat related example, with a clear explanation:

Excellent example. Thank you.