A window rain shield ventilator for installation in an open window, such ventilator having slideably extending first and second ventilator shield members attached, respectively, to first and second flange members, each flange member having at least one rotatable engagement member to aid in retaining the ventilator in the window’s sash channels. Predefined conditions are satisfied. The data carrier configured with the sleep mode switches over to a reception mode by means of a wake-up signal, whereby the wake-up signal additionally has a time datum that forms a countdown time, and switches the data carrier into the reception mode briefly, after this time has elapsed, thereby causing the data carrier to receive a command. The housing houses the inner tube and the collimating lens system. A strolling area is arranged between the outer border of the enclosed area and the central robot area with animal stalls that is divided into subareas in various ways by the use of separators that may include controlled one-way passing gates for the animals.