While I will defer to your knowledge of bat reproductive habits, I respectfully disagree on your observation regarding male<->female reproductive habits. While a female with the goal of producing a baby may be more inclined to give a BJ, the act of giving a BJ itself is not necessarily indicative of an increased likelihood of reproduction. It may also be indicative of a desire for consumption of semen, enjoyment of the act itself, or pity for the male's repeated request for the act to be performed.
This dialogue may also be indicative that I'm getting a little bit drunk.