|Digital cameras have anti-alias filters in front of the sensor to eliminate the Moire effect. By necessity that degrades image quality to the extent that the difference is visible as compared to one that was taken without an anti-alias filter. The moire effect particularly comes into play with images in which fine detail with different patterns and orientation feature, such as with architecture and fashion, and not with landscape, sports and macro photography. Not convinced about bird photography.
Question is: Do nature photographers really want an anti-alias filter in their camera? Do you perhaps see the Moire effect in some of your images anyway? And is the Moire effect really that unacceptable? It can be fairly satisfactorily PP removed except when very pronounced. As with lenses. it seems to me it may be a matter of horses for courses with cameras too.
Note: An anti-alias filter is a fixed element inside the camera. It either is there or it is not.