@jkent Normally, at first onset of season, the blood is dark red. As the time of ovulation (and therefore potentially successful mating) approaches, the blood get paler until it is almost straw coloured. THAT is when you need to be extra vigilant. You will also notice a swelling at the rear which is quite puffy and soft.
Some bitches have a longer 'window' than others. My Shani had about 4 hours when she could be mated, others 'last' for several days.
Thereafter the blood darkens again and gradually dries up, swelling goes down and all is over for another year.
If your girl is getting to the pale stage, I'd be extra careful !
Also MAKE notes, all the time through the season, so you know what to expect next time.
Because they are (normally) once-a-year girls, Basenjis often have a longer season - 28 days is quite usual.