Interesting. That study was limited to early aged male quail (only up to about 7 months of age and even then we are only talking about a drop to 84% fertile at 7 months), but they did reference a study about year olds and claimed it showed a "sharp drop". I cant get that study from 1983 to open, so I do not know what they consider a "sharp drop". If it is anything like the drop seen in this study, I would not consider going from 94% to 84% that bad.... If it is 84% at 7 months, I doubt it went to something crazy like 10% at a year.
Edit: Found it. This might be key.....and explain why my guys are still going strong...
"A series of experiments was conducted to study the decline in reproduction associated with age in the male Japanese quail. In Experiment 1, eggs were collected from pairs that were 28, 56, 107, and 149 weeks of age. Pairs that were 56 weeks of age or older showed a sharp drop in fertility and hatchability. Subsequent experiments were designed to study the endocrine and behavioral basis for this decline in the male. In Experiment 2, males that were between 23 and 70 weeks of age were tested for mating behavior, plasma testosterone was measured, and testes wet weight was determined. There were no significant differences between the age groups".
So we can infer that a year and a half old male could/might still be as fertile as a 23 week old bird...and that from the first study, this is upwards of 80% fertile. Also that the study you linked to is sort of not representing this second study accurately....I mean technically they did accurately report the first portion of the study, but conveniently left out the followup....
