Testosterone makes sparrows live fast, die early

With the male eye sparrow, there is a little more testosterone to make them more attractive to the females, while flying further and singing better.

Abundant male birds of masculine hormones also produce more young birds. However, assistant professor of biological sciences Wendy Reed at the University of North Dakota, USA, found the young birds born from testosterone dads are smaller and less likely to survive.

Testosterone levels make dark eyeballs more susceptible to disease and have a shorter lifespan. " They have a lower immunity and pay a lower rate of survival ," Reed said.

High levels of testosterone also turn male birds into bad fathers. They rarely visit the nest, bring less food and spend less time with their children.

Reed's group observed more than 400 groups of finches in the Appalachian mountains in Virginia for nine breeding seasons. They have bright chest hair, small beaks, head hair and darker wings.

A group of dark eyeballs were implanted with subcutaneous testosterone tubes to increase the level of male hormones.

" Usually, young males have lower testosterone levels than older females and are less flirtatious, weaker and have a softer coat ."

Adding testosterone makes birds more aggressive - they are more active on a large scale, but have higher levels of stress hormones. This can suppress the immune system and work too much, which can also draw attention.

" Although the young animals with testosterone supplements act like old ones, they do not have the same performance as older ones. Young males have fewer children, have lower birth success and longevity. also lower than the old ones . "

MT