Why did mother hummingbird leave her nest to let her chicks die?

Mother hummingbirds do not typically leave their nests to let their chicks die intentionally. However, if she does leave, it may be due to external stressors such as a threat from predators, lack of food, or illness, which can force her to prioritize her own survival. In some cases, if the chicks are weak or not thriving, she may instinctively recognize that they are unlikely to survive and choose to conserve her energy for future nesting attempts. This behavior is driven by natural instincts aimed at ensuring the continuation of her genes.