FIG. 1 is a perspective view of a motion detector head showing my new design;

FIG. 2 is a right elevational view of the motion detector head of FIG. 1; the left elevational view is a mirror image;

FIG. 3 is a top plan view thereof;

FIG. 4 is a front elevational view thereof;

FIG. 5 is a rear elevational view thereof; and,

FIG. 6 is a bottom plan view thereof, with the broken line shown for illustrative purposes only and forming no part of the claimed design.