9.3.4. The sign to diagram 551.1 (S13‑2‑1, see Figure 9-9) may be used only at a site which is approved as a migratory toad crossing. A list of currently approved sites is available from the Froglife Trust (www.froglife.org). The sign may be accompanied by a “for” and a distance plate. It should be displayed only during the migratory period. Signs should be removed or covered at other times of the year; it is recommended that flap-type signs be used to facilitate this.