Hmm, it may be a range then, or they changed it recently (in the past few days, as I've been too busy). A week ago when I paid attention, it was exactly on the hour mark 2x in a row from when I logged in first (logged in 9:09, saw spawns at 10:09 and 11:09), and exactly on the hour mark the day before that (logged in 21:23, saw a spawn at 22:23)
Today I tried it when I woke up, and it happened after about 45-50 minutes. Incidentally, that was also when the "global chat server" was down, and my tribble ate the food, but no new tribble appeared.
My first breeding tick today was 45 - 50 minutes after login (I logged in around 9:15, first tick was at 10:04), but after that they kept arriving every hour (confirmed 12:04, 13:04, and 14:04). So I'm beginning to think that the timer starts when you first log into the launcher (and today was a relatively big patch)
As for results, I decided that today will be a Saurian Brandy day in light of the new Mattson recipe (and I hate how bridge officer belts don't breed unless they are active, so it has to be a painstaking 1 per hour, since my bank is full of my tribble collection, and my inventory has my food)
(new to the table)
Rivera + Saurian Brandy = Deangelo
Cavallaro + Saurian Brandy = Mattson
(pink to purple in table)
Mattson + Saurian Brandy = Stahl (I was hoping it'd give me a Highson and the pink was wrong...)
(black in table, so no change)
Ricossa + Jumbo Romulan Mollusk = Griffis (yay for finding cheap food on the exchange!)
I think tomorrow I'll feed vendor buyable foods to Rivera...
(and to the above post, yes DS9 has Saurian Brandy at Quarks)
Well, on my main it was about 45 to 50 minutes before I spotted a tribble birth in my inventory with her 56% food. Jumped on my alt who is my 64% breeder and she has been logged in for about 2hrs now with a tribble and food item in her belt and nada. Just set up her inventory similar with vendor bought foods from Andoria and Dotson so will starting working on a Dotson 64% list to go with my tuffli 56% list. Then I will switch over
Edit: Rofl, I spoke too soon, within 10 minutes of posting this both belt and inventory tribbles were born. Will post the days breeding info before logging for the night.