Why are Robin eggs blue?

Wow it has been forever since I have blogged. I almost forgot that I said I would be blogging about why robins' eggs are blue, but luckily I remembered. I am sure you have all been SOOO anxious to find out ;-)

First, I went to "The Story of Robin Eggs." This was not the first thing that popped up, and did not even mention why the eggs are blue, but it had the ".org," so I thought I should check it out first. I did learn some really interesting facts though. Here are my favorite three:

1. A robin only lays one egg per day, and usually stops laying after four eggs.
2. A robin's typical body temparature is 104 degrees F...um wow!
3. The mommy robin does not leave the eggs for more than 5-10 minutes at a time. awwww :)

None of the "official" websites I found would talk about why robin eggs were blue, but I did find stuff on sciencedaily.com and it said the information was coming from a biology professor, so that has to be kind of legit right?

Robin eggs are blue because of a mucus that the mommy secretes while it is birthing the egg. So, I guess it isn't actually blue until it comes out into the world! The mucus is called biliverden. Here is what it said in the article:

"The blue colour in robin eggs is due to biliverdin, a pigment deposited on the eggshell when the female lays the eggs. There is some evidence that higher biliverdin levels indicate a healthier female and brighter blue eggs. Eggs laid by a healthier female seemed to encourage males to take more interest in their young." 

So, that is another interesting fact, the bluer the egg, the more the daddy will come and take care of the young birds. There are currently studies going on to find out WHY exactly they are like that. Any predictions? 

Sources:
http://www.sciencedaily.com/releases/2012/05/120514122838.htm
https://www.learner.org/jnorth/tm/robin/EggstraEggstra.html