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Categorized | Outdoors

Ranger Steve’s Nature Niche

Ranger Steve’s Nature Niche

We all wonder “why” but that is not a question scientists can address experimentally. That question is left to the philosophers and theologians. Scientists address the why question like the rest of society through a spiritual relationship and discussions.

The question scientists address experimentally is “how.” That fundamental difference in approach to problem solving has allowed for the tremendous advancements made in understanding how the world functions. At times, “how” appeared in conflict with “known” facts like: swallows spend the winter on the bottom of lakes, the sun rises and travels over the stationary Earth, or that the Earth is the center of the universe.

We now know by studying “how” that swallows migrate, the Earth rotates making the sun appear to rise and set, and the Earth revolves around the sun at the outer portion of a galaxy. For me, as a scientist, the “how” enhances the wonder of creation and gives deeper meaning for asking the supernatural question why? Why is outside the realm of science. By definition, science is restricted to studying the natural world.

To answer Jill’s question of how American Goldfinches change color for winter and its function, scientists have determined processes that bring about the change. It is multi-faceted and increases the bird’s survival chances.

Changes in day length are unconsciously perceived through the eye by the pituitary gland and that triggers hormone release into the blood to start chemical changes leading to feather molt.

Generally adult birds replace their entire plumage after breeding and only have a partial feather replacement during other seasonal molts. An orderly sequence is necessary in goldfinches to allow continued flight activity during the molt. Inner primary flight feathers and inner tail feathers are replaced first with other replacements occurring sequentially outward. This sequence can be seen easily in large birds like crows when they fly overhead. The same corresponding feathers are missing on opposite wings.

The survival advantage for goldfinches becoming dull during winter serves a few functions. It allows them to blend with the environment better and reduces predation threats. The bright summer color for males is used during the breeding season for claiming territory and dominance while seeking mates. It allows females to recognize them quickly as males. This may trigger a mating response or evasive behavior if they are “not in the mood.” The brighter color also distinguishes males so the females do not defend their nesting area from males and chase them away.

During the winter, survival demands are different. The bright plumage triggers are suitable during breeding season but would be a detriment in winter. As to why they do it, they do not know and it is not a choice. We all generally ask “why” when we are wondering “how.”

Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at the odybrook@chartermi.net. Ody Brook, 13010 Northland Dr, Cedar Springs, MI 49319-8433.

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