A goldfinch is a small bird sometimes depicted in paintings of the Christ Child; it is usually shown being held in his hands but is sometimes attached to a string.
Birds have been depicted since ancient times to signify a person's soul which was thought to fly away after death, but the goldfinch also more specifically alludes to the later Passion of Christ. According to apocryphal legend its red spot was acquired when it removed a thorn from Christ's head while he was on the way to Calvary, and was splashed with some of his blood.
However, other birds are often depicted beside the Infant Christ (see Cima's 'Virgin and Child'), and real children were sometimes given birds as pets.