Microblogging service Twitter has exploded in popularity on the back of celebrity tweeters such as Ashton Kutcher, Oprah Winfrey and Stephen Fry but over 60% of users stop visiting the site after a month, according to research.

The data from Nielsen Online, which measures internet traffic, shows that despite growing “exponentially” in the past few months the rate of retention is just 40%.

Before talk show queen Oprah Winfrey began singing Twitter’s praises and tweeting the retention rate was below 30%.

David Martin, Nielsen Online’s vice president of primary research, said in a blog post: “People are signing up in their droves and Twitter’s unique audience is up over 100% in March. But despite the hockey-stick growth chart, Twitter faces an uphill battle in making sure these flocks of new users are enticed to return to the nest.”

The figures reveal that Facebook and MySpace, which have seen similar explosive growth rates to Twitter, have much higher retention rates of nearly 70%.

Martin warns that there “simply aren’t enough new users to make up for defecting ones after a certain point”. He concludes: “Twitter has enjoyed a nice ride over the last few months, but it will not be able to sustain its meteoric rise without establishing a higher level of user loyalty. Frankly if Oprah can’t accomplish that, I’m not sure who can.”

(via Brand Republic)