Preheat oven to 300 degrees. In a small bowl, combine the crabmeat and chervil and toss gently. Cover and refrigerate.
Dry the veal with paper towels, then place each slice between 2 pieces of waxed paper and, using a meat mallet or other blunt instrument like a small saute pan, pound to about 1/4-inch thickness. Sprinkle the veal slices generously with salt and pepper, then lay 1 slice of ham on top of each slice. Top each piece of ham with 1/8 of the crabmeat mixture. Roll up each veal slice into a fat tube and secure with 1 or more toothpicks. If you have time, place the birdies in the refrigerator for 20 minutes; this will help keep them sealed as they cook.
In a large saute pan, melt 2 tablespoons of the butter over medium heat. Add the veal, in batches if necessary to avoid crowding, and cook until browned on all sides, 3 to 4 min1utes per side; transfer the birdies to an ovenproof platter as they are done. When all the birdies are browned, turn off the oven and place the platter in the oven while you prepare the sauce.
Add the capers to the pan and cook, stirring, for 3 minutes. Drain off the darkened butter, leaving the capers in the pan. Add the remaining 2 tablespoons butter to the pan. When the butter has melted, squeeze the lemon juice over the capers. Add the parsley and stir to combine. Season with salt and pepper, pour the sauce over the platter of veal birds, and serve right away.