Probably based on the level of SNP support in either the local council, Scottish or UK parliament elections - traditionally the Liberal Democrats were strong in the Highlands.

Not sure picking SNP support in an area is a great basis for predicting tonight's results though - a lot of people who would never vote SNP seem to be supporting the "Yes" campaign.

I plan on fast-forwarding through the next few hours with some help from our local water of life.

Edit: This might be a good source for where those number come from:

http://www.bbc.co.uk/news/special/vote2012/council/S12000017...

As it was a council election there appear to have been a lot of independents - so the proportion of seats won by the SNP looks relatively small even though they were the largest political party.

http://en.wikipedia.org/wiki/Highland_Council_election,_2012

Seems to be that the border colours represent previous SNP vote share and the middles will represent referendum declarations as they are announced. The numbers are projected declaration times.

low Scottish National Party voters