Boyd’s Bible Dictionary:
(cooer). The turtle embraces several species of plaintive-noted doves (Gen. 15:9; Psa. 74:19; Isa. 59:11). Those who could not afford the costlier sacrifices could offer two doves or pigeons (Lev. 12:6-8; Luke 2:24). They were migratory (Song of Sol. 2:12; Jer. 8:7).
Concise Bible Dictionary:
Where the word “turtle” occurs in the AV the “turtledove” is always to be understood. They are of the family of pigeons, and are plentiful in Palestine, of which there are several species. They could easily be procured by the poorest for the offerings, and a pair of them was brought when the Lord was presented in the temple (Gen. 15:9; Lev. 1:14; Lev. 5:7,11; Lev. 12:6,8; Num. 6:10; Psa. 74:19; Jer. 8:7; Luke 2:24). They are the harbinger of spring and when they return from their migration are a symbol of fruitfulness (Song of Sol. 2:12). The Turtur risorius is a dove found in Palestine. See DOVE.
Streptopelia Turtur—A turtle dove found in the Beyt Shean Valley.