Question

unusual bird parenting
birds have a reputation as excellent parents. they expend a great deal of effort in building nests in which to lay their eggs. they patiently incubate the eggs, keeping them warm and safe until they hatch. birds also bring food to their newly hatched offspring until the baby birds are independent. however, some unusual birds, known as brood parasites, dont provide any parental care for their young. perhaps the most famous brood parasite is the cuckoo. instead of building a nest, the cuckoo lays her eggs in the nest of another species with similar - looking eggs. the female cuckoo simply removes an egg laid by the host female, lays her own egg, and then leaves, expecting the host bird to care for the imposter.
what is the main, or central, idea of the passage?
unlike most species of birds, brood parasites such as the cuckoo dont provide any parental care.
most birds build nests for their young, incubate the eggs, and are generally devoted parents.
unlike most species of birds, brood parasites such as the cuckoo dont build nests.

Explanation:

El primer párrafo presenta la idea general de que la mayoría de las aves son excelentes padres, pero luego introduce una excepción: los parásitos de nidada. El segundo párrafo se centra en el cuco como ejemplo de parásito de nidada que no brinda cuidado parental. La idea principal no es solo que no construyen nidos (lo que es solo un detalle) ni que las aves en general son buenos padres (que es un antecedente), sino la comparación entre la mayoría de las aves y los parásitos de nidada en términos de cuidado parental.

Answer:

Unlike most species of birds, brood parasites such as the cuckoo don't provide any parental care.