Every October, thousands of Monarch butterflies migrate to Pacific Grove, California.  It makes for an amazing sight as they arrive en masse from all over the Western United States to spend the winter in the eucalyptus trees.  Over time, the natural habitat in Pacific Grove had declined, so the city has undertaken a preservation program, planting trees, mulching, and protecting habitat in a sanctuary.

It's a little-known fact that online communities migrate similarly, either finding a new permanent home, or simply returning again and again over time.

Why do they migrate?

If it's a permanent migration, the community may be rebelling against the management style. There are usually a lot of warning signs before this type of movement.  In some cases, the migration is a temporary thing, as members are attracted to a specific event occurring in another community (often associated with a TV season, a celebrity visit, or controversy). 

What if you are the host of an incoming migration?

• Institute the "no baggage rule" - tell everyone that old fights, cliques, and issues from the previous community are not welcome. You don't want to be re-refereeing old battles all day long.
• Make them welcome - roll out the red carpet for the new members, and make them feel a part of the community; consider posting a special announcement welcoming them specifically and giving a brief overview of how the community operates.
• Allow them to add their stamp, but be mindful of existing members feelings - when a new large group arrives, the existing members might feel overwhelmed by the perceived "takeover." This is when the community manager needs to step up and ensure that the old members are still recognized and heard.  You might consider special badges (like "founding member") or some recognition like that.
• Proactively try to connect the old members and new ones - if you see an opportunity to build bridges between the two groups, grab it! Start some conversations that will include everyone, and consider creating a space (a blog post or new discussion topic) where the two groups can get to know each other.
• If it's a very large group, or if it's a recurring spike, check your server capacity to ensure that you can handle the traffic - nothing would be worse than to offer a 404 message to your new visitors!

What if you are losing members to a migration outward?

• Make a connection with the ringleader(s) - there are usually a core group who are the instigators of the movement. Get in touch with them to see if there are legitimate grievances that can be managed.
• Continue to do new member outreach - don't give up. It's possible that the original member group wasn't a good fit for your community, and there might be others out there who would love your style.
• If you're the administrator, talk to your moderators - get feedback and see whether there are adjustments that can be made.  It's also possible that you need to change your moderators.
• Do not go over to the new community - whatever you do, do NOT post "please come back" messages in the new location your members chose.  It looks desperate and silly.
• If everything fails, consider a reboot - if you've lost most of your membership and you can't entice them back, consider talking to your remaining members and asking them for input. You might need a total refresh of focus, subject area, or platform to revitalize the community.  If you decide to move forward, include the members in your thought process.

Have you ever been part of a community that migrated?  What was the trigger?  Please feel free to share your own experiences here.