This is a monthly series that looks at visitor data for all the major social networks as calculated by Compete.com. Compete is USA-biased, and certainly in the case of Twitter the visitor numbers are distorted by the openness of Twitter’s API and the numerous Twitter software clients, but on a like-for-like basis the numerics have value and warrant investigation. Please refer to previous installments in this series for a more detailed overview.

Unique visitors to Twitter.com fell for the third successive month, dropping 2.43% overall, to 22,481,568, according to Compete.com. More concerning for the network was a -7.24% dip in overall visits.

(click to enlarge)

Overall, traffic to all social media fell, with Facebook losing -0.47% to 128,339,156 unique visitors for November, but gaining 3.51% to 2,601,399,595 visitors overall.

Friendfeed fell sharply, down 20.95% to just 552,147 uniques, and has now lost almost half of its unique visitors since peaking at 1,044,326 in August. Overall visitors fell 26.62%.

LinkedIn, which has been the social media star the past five or six months, fell for the first time since May, losing 6.93% of unique visitors, and 11.53% overall.

MySpace dipped -2.64%, and -3.08% overall.

Plurk, which was once considered a rival to Twitter, saw just over two hundred thousand unique visitors for the month, and surely will not last much into 2010.