In ethological as well as in physiological research it is of interest to measure the amount of food consumed by an individual. While this is an easy task in animals kept solitarily it often is problematic in species kept in groups. Here, individual food consumption typically can only be measured with some interference from the experimenter and thus disturbance of the animals. To investigate the behaviour and the maternal investment of communally nursing house mice we developed an automatic device that allows to individually control and measure the food intake of female mice kept in groups. For this purpose we use an automatic identification system that triggers an individual's access to a feeding station. For identification we use subcutaneously implanted microchips (transponder) with a diameter of 2.1 mm and a length of 11 mm. An electromagnetic field at the entrance of the feeding station, tuned to the transponders' frequency, allows to discriminate between individuals according to their microchip. The feeding device consists of a movable hollow metal arm filled with commercial food pellets. In case of correct identification, the metal arm will be moved by a little servomotor in close contact to the lid of the cage, so that the animal can feed on the pellets as long as it remains in the feeding station. We not only use this device to quantify food consumption but also to individually limit the daily amount of food available.

This fairly simple method of identifying animals with passive transponders can also be used to control individual access to other resources like nesting sites or mating partners. With the help of several such reading devices it is also possible to register the movements of individuals in a seminatural enclosure.