Abstract: A pet litter box system comprising a base tray with a non-apertured bottom wall and a plurality of sifting trays each with an apertured bottom wall, the sifting trays formed of molded pulp material. The sifting trays and base nest together. The system may include an upper shield seated on the nested sifting trays to contain litter that is kicked up by a cat utilizing the tray system. The shield may be formed of pulp and inverted to receive nested pulp sifting trays to define a transport or storage mode, the shield enhancing the combined structure in the transport or storage mode.