What gives a male widowbird greater reproductive success?

Food and feeding

The long-tailed widowbird's diet generally consists of seeds, supplemented occasionally by arthropods. The birds do most of their foraging in flocks on the ground, though they are occasionally observed hawking insects airily.

protistas excret ethanol used in the manufacture of vinegar

protein makes up the building blocks of organs, muscles, skin, hormones and pretty much everything that matters in your body.

some choices are:

peanut butter

seeds

eggs

yogurt

meats

fish

so pretty much meat, dairy, nuts, and grains.