Every now and then I got a glimpse of this bird which I'm pretty sure is not native to Northern Germany where I live. There are at least three of these birds around but I usually only see something quick and green somewhere in the trees. I finally managed to get some decent pictures so I'm hoping someone can tell me what kind of bird this is. I'm curious what biological niche this bird is likely to fill and which native species it might compete with.
Almost definitely (I'm not a regular birder) European Green Woodpecker (latin name: Picus viridis) and it is native to your area according to its species distribution map.
"Green woodpeckers are the largest and most colourful woodpeckers native to Britain. They are easily recognised by their laughing ‘yaffle’ call, which they use to demarcate their territory. They also drum on trees, though the sound is not as resonant as that made by the other two British species (the greater and lesser spotted woodpeckers). Green woodpeckers survive on a diet of insects and have a particular fondness for ants. They return day after day to their favourite ant hill to feed." - BBC nature
