This is what probably happened to Lauren's birds. You can read the comments yourself by pressing the Owl button and selecting Robin Sightings. These are albino robins, and there's an explanation for their different coloring. Pigments are the chemicals in our bodies that give us our colors. When a bird or other animal makes no pigments, the condition is called albinism, and the animal is called an albino.
Some animals make normal pigments in parts of their bodies and no pigments in others.
These are called partial albinos. For some reason, albinism and partial albinism have been recorded in robins more than any other wild bird species. Journey North observers have occasionally reported albino robins. John Holbrook recently reported seeing a partial albino near Schreiber Gym on the campus of the University of Montana in Missoula on March 3. Several others saw this bird in February and March at various locations across campus.