The a large group of animals migrates from a summer breeding ground to a warmer winter ground. which type of adaptation does this statement describe?

chemical adaptation

behavioral adaptation

structural adaptation

This statement describes behavioural adaptation.  

behavioural adaptation

Explanation:

The conditions of the environment don’t always remain constant. Instead it is always changing. Thus the organisms that live on different environments have to find suitable ways to adapt to the changes in the environment and ensure their survival.  

By bringing changes in their behaviour organisms try to adapt to environmental changes. Migration is an example of behavioural change. When the conditions of the living environment change,  making it a place difficult to thrive upon, organisms temporarily migrate from the area to more comfortable regions.  

Summer and winter sleep habits of several organisms are also examples of behavioural adaptation.