How many species does the sternidae family have worldwide with less than 9 species on Réunion?
CREATE TABLE "birds" (
  "species" text,
  "order" text,
  "family" text,
  "species_worldwide" real,
  "species_on_r_union" real
);
SELECT COUNT("species_worldwide") FROM "birds" WHERE "family"='sternidae' AND "species_on_r_union"<9;