yes
It depends on the bird, they all look different in some way. Males are usually more colorful than females
Depends. They can be different colors, but males are bigger. And females have different privet parts than males of corse so short answer, no.
Some of the websites that offer romantic gifts for males is Lovers Lanes. They have different type of romantic gifts for males and females. It would be a website to look into.
the males compete to fertilize
Guess: To attract females, the males show off (generically). To keep from being eaten, females look less attractive (muted colors).
You look at the eyelashes.
they look different
Males have a shorter legs than females do. Males are smaller than females. Males bark if they feel safe in their habitat while females make a quiet croaking sound.
It is actually vice versa... The male's attract the females. The males usually try to make themselves look dominant by rising their heads up high. This will usually proceed into a fight with rivals. Another way of attract female's is to make low frequency noises. You can tell if a crocodile is doing this when you see the droplets of water bouncing off their backs.
males in the population look distinctly different than females
They really don't. Males have a larger brow line than females do but they were (at one time) the same. The males sex hormones changed that look. Testosterone is the reason why.
No, there are more males in the world. World wide, there are roughly 101 males for every 100 females. If you look at a break down by country, more countries have a higher number of females than they do males. See the related link for more information.