Nature is secretive and does not always give its treasures away very easily...
If you want to observe Marmots, hear their whistling, follow Isard tracks, name flowers, recognize birdsongs and animal calls, learn about landscape reading, meet a shepherd, identify animal tracks, etc. You will certainly have to walk but you will also have to learn about the mountains : the hard life of plants and animals at altitude,

the function of the herds, the managing of grazing land, etc. !
To answer these questions, the Pyrenees National Park and its park wardens organize a "discovery" programme each Summer : "Life in the streams", "In search of Isards", "History of a volcano", "A park warden's day", etc.
You may refer to this programme as from June.

You can also contact the Mountain Leaders, Leaders who work in partnership with the Pyrenees National Park. You will find their selection of "Nature walks" fascinating ("Birds of prey", "Wetland Flora", "Marmots", etc.).

Also try not to miss the "Points rencontre" (meeting points) which are organized by the Park wardens in Summer by the side of many paths, they will answer all your questions.
There is nothing better than the presence of a professional to awaken your senses and teach you to listen to Nature.