What are the little brown birds that hang around with pheasants? I always thought they were grouse but someone said today they are female pheasants

For those who have forgotten their school biology, sexual dimorphism is actually pretty cool… Evolution has resulted in the males and females of many animals being very different sizes and/or characteristics (like colour etc). This reason this is beneficial is it makes “one of them” more resilient to environmental changes and hence the likelihood of children surviving. For example, if both parents eat spider sized things and one year there’s almost no spiders, the parents (and hence kids) will starve, however if one parent is big and ears mouse sized things, it wont be affected by the spider collapse and survive and the kid (genes) will carry. Similarly if everything is a certain shade of brown but one day a drought makes everything redder, one parent will still be camouflaged and survive.