For the daytime whistlers frequently observed in the late afternoon at low latitudes, ducted propagation has been experimentally evidenced, and association with the equatorial anomaly has been suggested. It is suggested from the present computations of ray tracing and wave absorption that the ground-based daytime whistlers may be attributed to propagation trapped in field-aligned structures of electron density (ducts) with a small dimension of 10--50 km width and a large enhancement factor of 100--300% either present within or superimposed on the high-latitude flank of the equatorial anomaly. We predict a low-latitude cutoff of occurrence of the daytime whistlers at a geomagnetic latitude of ~20¿, as experimentally established.