<p>When merging tags, the tag wiki (and excerpt) are transferred to the destination tag <em>only</em> if the destination tag does not already have a wiki. This behavior allows tags to be <em>renamed</em> via merging while avoiding the danger of potentially destroying a useful wiki.</p>

<p>After merging, the old tag still exists for a brief period - there are no questions in it, but the records are still around. After that's cleaned up, its wiki is considered "orphaned"; moderators have a handy list of these available in their toolbox, but if you're interested you can find them yourself <a href="http://data.stackexchange.com/stats/query/876067/orphaned-tag-wikis" rel="nofollow noreferrer">in the Data Explorer</a>.</p>
