It’s no secret that welcoming visitors to your site that are coming from a known location increases those visitors’ primary engagement metrics. Pages per visits and time on site goes up, bounce rate goes down.

Where this becomes extremely interesting is when that traffic is coming from a social bookmarking site. We get a lot of traffic from StumbleUpon, so in our blogs we set up dedicated messages to welcome returning and first-time Stumblers. It has changed spikes of traffics into long run-off ramps. The importance of this referrer message was driven home when we a cat blog entry became a thumbs-up hit on StumbleUpon but we had forgotten to activate the refer message.

This screen shot shows a spike of 12,309 visitors from StumbleUpon on April 12th to The Cat’s Meow, our cats and kittens blog with another 3,100 visits since then.

The second screen shot shows a spike of 12,180 visitors to Snuzzy our cute and fuzzy blog on January 27th that led to another 80,000 visitors in the ensuing 2 weeks.

These results may be above average, the next time we get a hit from StumbleUpon to our cat blog (after we’ve resumed showing the helpful message to Stumblers) I’ll post the results. But without a doubt the blogs that have Stumbler referrer messages no longer see towering visitor spikes and instead show much more meaningful long run-off ramps.

UPDATE: 4/21/09
Some readers did not understand why referrer messages are so effective for visitors from social bookmarking sites. To clarify I’ve added a screenshot of the message shown to a repeat visitor from StumbleUpon. Note that the first option is for them to StumbleUp. We also quickly remind them what content we post on our site, make it easy for them to join our community on SU, as well as subscribe to the blog feed, and also to join our community and explore some existing crowd-pleaser posts.