Scarlet Tanager – News & Stories

“The color serves as a signaling device to other males, telling them to stay away from their territory,” Dunning said. It signals to women in a different way. “The brighter the male, the more likely he is to mate with the best females.”

During the breeding season, scarlet tanagers mainly eat insects. In the fall, their diet consists mainly of fruit. Fruits are full of sugar, which tanagers turn into fat.

“To make long journeys, tanagers must enrich themselves with migratory fat. They can increase their body weight by more than 50%. Gram for gram, fats store even more energy than carbohydrates.

Migration can be demanding. Their journey to South America sometimes stretches over 4,000 miles, and the 500-mile crossing of the Gulf of Mexico offers no opportunity for rest.

While people may assume that changes in temperature or food availability trigger migrations like these, that is not the case.

“In the fall, people ask me if they should leave their bird feeders up,” Dunning said. “They fear that the food supply will encourage the birds to stay north too long. There is no need to worry. Truly migratory species use the length of the night to determine when they leave. It signals hormonal changes that cause physiological responses.

Scientists are studying migratory restlessness, also known as Zugunruhe, to learn more about these behaviors.

“If you put a scarlet tanager in captivity, it will nervously jump around its cage as if trying to migrate when the days change in length. If you show them something like the moon or the stars they are orienting towards in the fall, migrating birds will mostly jump south.

The effect is similar in spring when appropriate cues encourage them to jump north. “They will even respond to signals like polarized sunlight. With a few benchmarks, they are heading in the right direction. If you remove these signals, the birds jump in random directions.

Outside the cage, however, scarlet tanagers take flight, bringing their unexpected burst of red to the treetops of Indiana.