IIRC, they did not, and it pretty much ruined the story for me. There would have been ecological chaos.
Now that I think back some more, I recall that there were several alternative hypotheses* of what caused the great die-off. Maybe having all male mammals die instead of just all male humans left open the possibility that whatever it was wasn’t human-centric. *I think it was eventually supposed to have been a bioweapon; but one that caused every male mammal on Earth to instantly die at the same second? I don’t buy it.
I’m sure I have read at least one SciFi story where a virus deliberately crafted to attack Y chromosomes was part of the plot. Doesn’t pass any sort of reasonable reality check, but that isn’t the point.
Of course you end up with something more akin to 12 Monkeys. Some always survive. Humans don’t have a great deal of genetic diversity but with a few billion out there the chances of a 100.0000000% kill rate is rather low. Same for other species. There will be pockets of survival. The outcome becomes much more interesting. Maybe mammals stage a comeback as even the small number of survivors have some traits that give them an advantage. A few million years later and they may be back in the ascendent.