1. Genetics: The color of feathers is determined by pigments produced by specialized cells called melanocytes. Different genes control the production and distribution of these pigments, and the expression of these genes can vary between juvenile and adult stages. This leads to differences in feather coloration between hatchlings and adults.
2. Diet: Some birds' feathers may change color as they grow and molt due to changes in their diet. For example, some species of birds may have brightly colored feathers during breeding season when they are consuming a diet rich in certain pigments, but their feathers may become duller or change color outside of breeding season when their diet changes.
3. Structural Differences: The structure of feathers can also affect their color. Hatchlings' feathers may have a different structure compared to adult feathers, leading to differences in light reflection and color perception.
4. Environmental Factors: In some cases, environmental factors such as sunlight, humidity, and temperature can influence feather color. As hatchlings grow and develop, their feathers may be exposed to different environmental conditions that can subtly alter their coloration.
It's worth noting that not all baby birds have feathers that are a different color from adults. Some species may have hatchlings with feathers that closely resemble their adult plumage.