Is there production of TDF in birds? If so which gene produces it?
Sex Determination System
Birds have a ZW sex determination system meaning that males are the homogametic sex. Or yet, in other words, males have two Z chromosomes while females have one Z and one W chromosome. You might want to have a look at Do males of all sexual species have Y chromosomes? for a short review of the diversity of sex determination system.
Sex determining locus
The DMRT1 gene on the Z chromosome appears to be important for male sex determination by affecting the testicular marker, SOX9 however it might not be the whole story (Smith et al. 2009). It is possible that several loci are involved in determining sex in birds.