This final Alert is also the most personalized, using the lists that you have in eBird to build your custom list of birds that you "need" for any specific region. The word "need" is used loosely here to mean a species that you have not seen in that region, whether it be county, state/province, or country. Needs Alerts are powerful in that they can both show the species that you need for that region all-time, or for this year alone. They cover species that might be omitted from the previous alerts, if those species are common ones that wouldn't trip the Rare Bird Alert. Combining this with the previous alerts is a great way to paint a complete picture of both the rarities that occur in an area, as well as what species you might be personally interested in seeing.
As seen in the image one paragraph above, you can choose whether to show the Needs Alert for "This year only", or for all years. The default is having this box unchecked, showing all years.
The above two images show the display for both the all-years alert (Needs Alert), and the year-specific one (Year Needs Alert).