Nest like structures in tree?

Hi everyone

I'm on holidays in Paris, and have noticed lots of these little nestlike structures in the trees.

I haven't noticed anything like this in my country (Australia), so I'm just curious, is this some kind of nest? And if so, does anyone know what animal created these?

Thank you!

Hi everyone

I'm on holidays in Paris, and have noticed lots of these little nestlike structures in the trees.

I haven't noticed anything like this in my country (Australia), so I'm just curious, is this some kind of nest? And if so, does anyone know what animal created these?

Thank you!