With its huge zoom the P900 is a great Bridge camera for long range photography. So for wildlife, although quite a bulky camera, it fits the bill really well. And for "birding" - taking pictures of birds if you don't know what that means, it's great. It even has a dedicated bird mode. However, there are many things to learn about this mode and the camera overall in order to get the absolute best results.
Books, including paperback, kindle and PDF format, have been written about how to master not only the camera overall, but also bird mode specifically. No need to worry though if your a novice, even with just the standard settings being used, basically anyone is capable of capturing spectacular images after a bit of practice. Take a look at some of the photos in this blog post of birds that were all shot with the Nikon P900. If your after an enhanced / upgraded version of the P900 give the Nikon P950 a look.