Count Only Unique Data Points By Day

Hello all!

I feel like this shouldn't be so hard but I can't figure anything out and when I search existing posts the formulas are so complex and customized that I can't make sense of them. I am a birder and keep detailed records of my finds and I simply love having way too many options to customize the information I can get back out of a workbook. Attached you will find a very, very condensed sample of relevant data. While it is only text, in reality these are nearly all pulling from various other sources, but I don't see how that will harm anything.

The goal is to get an easily updatable (automatic), sortable set of numbers, one for each date. I want to see how many unique species I saw in a day regardless of how many I saw or how many places I saw them. So two Northern Cardinals seen at four different sites should only count for a single tally for the day.

For the data given the results should read:

5/15/2013: 42
5/17/2013: 16
5/20/2013: 16
5/22/2013: 64
5/25/2013: 27
5/27/2013: 25

And again, sortable by numeric result is the key. Thank you for looking and at least checking this out for me!

Benjamin