Why?
According to the Washington Post, Elon Musk "says he will reinstate accounts suspended for threats, harassment and misinformation beginning next week" and he "plans to reinstate nearly all previously banned Twitter accounts". Thus any doubts about Twitter devolving into a free-for-all hellscape should be eviscerated.
Luckily, the FOSS community has created a viable alternative to Twitter that people are migrating to by the thousands. It is a platform that is well aligned with our values - civility, transparency, decentralization, freedom from corporate (and space Karen) influence, protection of marginalized voices, and protection of privacy.
As leaders in the Free Culture and FOSS communities, and as an organization that opposes misinformation, online harassment, racism, sexism, homophobia, antisemitism, etc. we should have a strong official presence on Mastodon (and provide our followers an easy off-ramp from Twitter). And although it may sound like a radical idea currently, we should think about the possibility of eventually leaving Twitter entirely in case it fully implodes.
How?
It looks like someone may have already begun the mirroring process: https://twtr.plus/users/wikipedia. However, it doesn't look like twtr.plus is going to be a viable option as the instance is currently at 1076% saturation of its Twitter API usage (no doubt caused by the Twitter exodus). We could instead set up our own BirdsiteLIVE server or find another mirroring server that isn't saturated. Alternatively, we could just set up a regular Mastodon account on a regular Mastodon instance and use 3rd party (moa.party) or in-house (mastodon-bot, mastodon-twitter-sync, etc.) tools to crosspost. Perhaps the WMF Communications team is even already using crossposting tools for crossposting to Facebook, Instagram, etc. I have no idea. This approach would make it easier for us to stop posting to Twitter in the future if we so choose.
There is also a Wikipedia Mastodon account at mastodon.social that has never made a post. The account was created back in 2019 and I have no idea if it's controlled by the WMF or not.