Springtime is great for wildlife. All critters great and small are in the mood for love and show it to the world. Walking with a long lens like a 500mm or longer is then a must. As the season moves on, things get quieter. Awfully quiet.
The birds are nesting in the most remote places they can find, out of sight, out of mind. The trees are fully covered in leaves and everything is quiet. You only see the odd bird out, looking for some food.