CREATE TABLE table_69851 ("Species" TEXT, "Order" TEXT, "Family" TEXT, "Species worldwide" FLOAT, "Species on R\\u00e9union" FLOAT)

Which species on R union island is part of the procellariiformes order and is part of the hydrobatidae family and has less than 21 species worldwide?
SELECT SUM("Species on R\u00e9union") FROM table_69851 WHERE "Order" = 'procellariiformes' AND "Family" = 'hydrobatidae' AND "Species worldwide" < '21'
SELECT SUM("Species on R\u00e9union") FROM "table_69851" WHERE "Family" = 'hydrobatidae' AND "Order" = 'procellariiformes' AND "Species worldwide" < '21'