How do auxiliary birds increase their fitness even though they don't have a monogamous mate?

ANSWER:

In polygamous conditions, the male has multiple partners at a time and also does spend much time on exhibiting parental care.

EXPLANATION:

Monogamous pairing is a system where in the male and a single female organisms belonging to a species pair bond to raise offspring. There are many species of birds which have adopted monogamy with great success. Monogamy tends to also occur when populations are small and dispersed and hence helps in the easy increase in the population number without having to waste energy searching for other females. Auxiliary birds are polygamous in nature and here, the male would spend much more time searching for another mate. But in this condition, the male sets in a mating behaviour with multiple partners at a time and also does not seem to spend much time on exhibiting parental care. Hence, saves time for the search of a new mate.