I thought I would add to Wayne's suggestion and mention that you can
actually filter the map view to show only sitings from a specific
month and year, so it is possible to generate a map of sitings for a
specific species in that given time frame. I use this all the time
when I'm traveling to find local birds that I would like to see.

Here is a link to TUVU sitings from Washington in August 2012, click
"Show Points Sooner" to see the individual siting locations:

http://tinyurl.com/EbirdTVs

Additionally, it is possible to set up daily or even hourly alerts for
species you haven't logged on eBird in a given state or county. It
would be possible to set up a dummy eBird account and get a daily list
of every bird seen in Washington. From there, you could pull out and
log all the Turkey Vulture reports. The only downside is that you
might miss data that had been entered more than a few days after the
siting.

eBird is an absolutely wonderful tool and becomes better as more
people contribute their data. I highly encourage anyone who hasn't
tried using it to give it a shot.

Josh Adams
Lynnwood, WA