 How does the "pigeon milk" produced by both parent pigeons play a role in the early nutrition of a pigeon chick?
Pigeons, along with doves and flamingos, possess a unique trait among birds: they produce a special substance known as "crop milk" or "pigeon milk" to feed their young. This substance is not milk in the mammalian sense, but it serves a similar nutritional purpose.

Pigeon milk is produced in the crop of both male and female adult pigeons, a region of the bird's esophagus used for food storage. Around the time the eggs are due to hatch, the cells lining the crop of the parent birds begin to proliferate and secrete a thick, nutritious substance, rich in proteins and fats, similar to mammalian milk.

Unlike most birds, which typically feed their hatchlings with regurgitated food, pigeons feed their young this crop milk during the first week of their life. It's highly nutritious, containing more protein and fat than either cow or human milk, and it also contains antioxidants and immune-boosting proteins, which help protect the chick from disease.