Singers love to eat. The following ingredients should be provided regularly: Finchmix, Niger/Thistle, Greens, hard boiled egg mashed with shell, sprouted soaked seed, millet sprigs, Canary seed, rapeseed.
Added extras that will boost breeding and overall contentness include: small sized mealworms, cornbread, shredded carrot, dried fruits, sunflower seeds (saltless), whole wheat bread, peanut butter, whiteworms, veggies (like brocolli, kale), spirulina, benebac, apples, and whiteworms.
The author of this page has noticed that Singers really love their greenfood. Usually not a shred remains in the cage after a very short time. This favorite should be provided well washed at least 2-3 times per week.
During breeding season, provide as many of the extras (worms in particular) as you possibly can. If there is a shortage of food, the parents will see that as a threat to the clutch and could abandon the young.