While some female birds do engage in extra-pair copulations (mating with males other than their social partner), it's not primarily to protect their young. Extra-pair copulations can serve various functions, such as increasing genetic diversity in offspring, gaining access to better-quality genes, or obtaining material benefits (like food) from the additional males.

The main purpose of female birds mating with multiple males is not directly related to protecting their young. However, it's important to note that mating strategies in birds can vary widely depending on the species and ecological context.