Some of these traits also represent energetically costly investments for the animals that bear them.

Migration being energetically costly has been studied in the context of life-history strategies.

Reproduction is energetically costly to the male.

Calling is postulated to be energetically costly to anurans in general.

The scarcity of food makes fighting energetically costly, so encounters between males usually only involve display.

Though this might seem energetically costly, the worms' presence in an animal's digestive system means they never want for food.

Although this process is energetically costly is it crucial to their survival in hypoxic waters.

The traits that are selected for, may be energetically costly to maintain and may cause increased predation.

Harems can prove energetically costly for both males and females.

All animals must forage for food in order to meet their energetic needs, but doing so is energetically costly.