Flagging on Birch Tree - Mt Tecumseh Trail (2012) Legitimate Flagging (survey tape) - On a trail inspection with a Forest Service assistant district ranger in 2012, a topic of discussion was survey flagging tape on trees along the White Mountains trail system. It needs to be pointed out that some of the survey flagging tape you see along trails in the White Mountains marks trees that are being used for research. Much of this flagging has no identifying marks ...