The Phillips Lab

Behavioral Testing Facility (BTF)

The consists of central holding/utility and storage buildings surrounded by four testing buildings. The four testing buildings are: (1) constructed of non-magnetic materials to minimize distortion of the ambient magnetic field, (2) built with double walls (a "building inside a building") to dampen sound and maintain temperature, (3) heated and cooled by means of underground air ducts from the central utility building to minimize disturbance, and (4) supplied with filtered electrical power to minimize radio frequency interference. In addition, one of the testing buildings is surrounded by four outdoor training tanks (see below). Water temperature in the training tanks is regulated by means of heat exchangers connected by underground pipes to recirculating heater/coolers located in the central utilility building.

Coils and Magnetometer Systems

Changes in the magnetic field are produced using cube surface coils, which create highly uniform artificial fields over large volumes (for a discussion of alternative coil designs see Kirschvink (1992): Bioelectromagnetics 13: 401-411). The standard protocol used in our behavioral experiments consists of testing an equal number of animals in each of four symmetrical magnetic field alignments, i.e., magnetic north at geographic north, south, east and west. The double coil system used to produce the four field alignments is discussed in Phillips (1986a). When magnetic bearings from an equal number of animals tested in each of the four magnetic field alignments are pooled, any consistent non-magnetic bias is eliminated from the resulting distribution. Coil systems used to produce small changes in the inclination and/or intensity of the magnetic field for navigational map experiments are described in Fischer et al. (2000).

Magnetic field measurements are carried out using a 3-axis flux gate magnetometer. When precise measurements of magnetic inclination are required, the 3-axis magnetometer probe is mounted on an adjustable polished glass surface, which can be leveled to within 0.001 degrees of horizontal using a precision electronic level.

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