Wakwak
Wakwak is a Philippine name for a bird-like night creature said to carry people off. Some use it as another word for the aswang; others treat it as a being of its own.
Fletcher Gardner, writing in the Journal of American Folk-Lore in 1906, said Bisayans often called the asuang wakwak, that Tagalogs understood the word, and that the reverse held too. In Pampangan the words were asuang and ustuang. He cited a Pampangan dictionary describing a man who oils himself, flies to a woman with child and draws the baby out before birth. Padre Ortiz, Gardner added, gave that role to the patianak.
Wikipedia describes the wakwak as a vampiric, bird-like creature that seizes people at night in rural areas, much like the manananggal and the Ekek. It says the wakwak cannot detach its torso, which the manananggal can. Some treat it as a kind of vampire. Others say the name belongs to a night bird linked with witches.
Wikipedia's aswang article adds that the tiktik and wakwak calls credited to the aswang sound like bats and Philippine flying lemurs, known locally as kagwang. Those animals have been hunted by people who suspected them of being aswang in disguise.
"The asuang is often called wakwak by Bisayans, and the term is understood by Tagalogs ; the converse being also true, that the Bisayans understand the word "asuang." In Pampangan, the word " asuang " and a variant " ustuang " are used. Padre Bergafio, in his Pampangan Dictionary, says : " It is said to be a man, who, anointing his body with oil, flies to a pregnant woman, and draws her unborn child from the womb." Padre Ortiz, elsewhere quoted, speaks of this as being the particular sphere of action of the patianak."