The swan is a large, graceful water bird with a long, slender curving neck. Some swans may weigh as much as forty pounds (18.1 kilograms) and may have a wingspan of as much as eight feet (2.4 meters).
The Hebrew name (tin·sheʹmeth), appearing in the list of unclean flying creatures (Lev. 11:13, 18; Deut. 14:12, 16), is thought to mean a “hard breather” or “snorter.” It may describe the swan with its loud hissing sound, made when the bird is excited or angered, and is so rendered in a number of translations (AV, Da, Le, NW, Ro, Yg). This identification dates back at least to the Latin Vulgate, in which Jerome rendered the Hebrew tin·sheʹmeth (at Leviticus 11:18) by the Latin word cygnus (“swan”). The earlier Greek Septuagint here reads “purple-colored bird” (Gr., por·phy·riʹon), evidently the purple gallinule or water hen. However, both of these ancient versions translate tin·sheʹmeth as “ibis” at Deuteronomy 14:16, thus showing their uncertainty.
The swan, though found in Palestine, is not common there in modern times. Because of this, and also due to the fact that the swan is primarily a vegetarian as to diet, many modern translators prefer to identify the tin·sheʹmeth with the “water hen” (RS, Mo), “eagle-owl” (AT), “ibis” (JB), or with other birds known to be either carnivorous or scavengers. However, the rarity of the appearance of swans in Palestine in modern times is not a certain evidence that they were not more common there in ancient times. Likewise, it must be recognized that the view that the classification of certain birds as unclean depended upon their being either raptorial or scavengers is only a deduction and is not directly stated in the Bible.
In addition to its usual diet of seeds, roots of water plants, and worms, the swan is known to feed on shellfish.