In former times, much of the island was covered with a Pisonia grandis forest, in which
large numbers of seabirds nested. The coral rock was thus covered with guano.
The guano, and since the 1950s also the rock and sand into which the phosphate
had been leached, were mined away between 1906 and 1972 converting an island
once densely forested to the current barren, pitted landscape. During that
time, a small workers' settlement existed in the NW of St Pierre, which
depended on supplies shipped in from abroad.