I have nothing against pigeons. There are supposed to be some 80.000 living in Paris. Until some 100 years ago you found them only in specific dove-cots, and they were basically used as carrier pigeons, but today they have a completely free life and are clearly increasing in number. You are not supposed to feed them, but some people do ... and this leads to some local very high concentration, in this case just in front of Notre Dame. Of course, during winter, they must be struggling for food. (The Paris Township offers some dove-cuts where they can live comfortably, but they are then also offered food which is supposed to make them sterile.)
I haven’t found any indications of how many seagulls we can find in Paris, but here also the number is clearly increasing. To a large extent it’s however a seasonal issue; they are mostly here during the winter months, leaving the coastlines, following the Seine. Many have obviously travelled from far. They seemed not to be interested in the pigeon food, sitting in the background, calmly watching the tumult.