Final answer:
Bird watcher Cory estimates that 30 birds lay eggs in the summer, with species such as robins typically laying four eggs, and both parents providing care through incubation. Monogamous bird species, which make up 90% to 95% of all birds, exhibit shared parental responsibilities, and males are highly involved in caring for the eggs and hatchlings.
Step-by-step explanation:
Cory, a bird watcher, estimates that 30 birds lay eggs in the summer. Ornithologists who study bird behaviors have observed that many birds, including species like the robin, frequently lay their eggs during the summer months. Robins, for instance, are known to lay an average of four eggs, representing an evolutionary strategy known as stabilizing selection. Producing more than four eggs could result in undernourished chicks, while fewer eggs may lead to no viable offspring, hence four is the optimal number for survival and proper nourishment.
Parental care is crucial in avian species, as 90% to 95% of bird species are monogamous, with both the male and female participating in the breeding process for several years or until one mate passes away. They share the task of incubating the eggs, which often begins after the last egg is laid. During incubation, parents alternate in keeping the eggs warm, ensuring the development of the embryos inside the eggs.
After laying eggs, birds engage in a process called brooding, where they use body heat to keep the eggs warm. This is essential for the development of the chicks inside the eggs. Male involvement in avian parental care is significant, as male birds are one of the few nonhuman vertebrates that exhibit such a high level of care towards their offspring.