Conv2d is a module.  In the source for nn.Conv2d, Conv2d inherits from _ConvNd which in turn inherits from Module. On the other hand, nn.Parameter inherits from torch.Tensor. From what I understand, this implies that the parameters, although learnable, are not part of the Model to begin with and any operation involving it is dynamically computed. This is why initializing  torch.ones in the init section does not add that variable to the model.