In Carmen 2, one of his poems about his ex-girlfriend, Lesbia (the code name for a woman who is usually assumed to be the licentious sister of the transvestite trouble-maker Clodius Pulcher), Catullus uses the term passer, which translates as 'sparrow'. It is usually assumed that 'passer' is some sort of term of affection, and it has been noted that it has been used as a term of affection elsewhere in Latin literature. However, the Rogue Classicist has found some funerary inscriptions for pets on the Sauvage Noble blog, that make it sound quite possible that Catullus was actually mourning the death of his or Lesbia's pet sparrow. Since the next sparrow poem by Catullus begins by calling on Venus and Cupid, it still sounds unlikely, but you may judge for yourself.
There is also a recipe for passer based on ancient Roman cooking, accompanied by a picture of "Passer in sarcophago," in which the sarcophagus is actually puff pastry.