Windows paths may contain a colon : as a part of drive designation and backslashes (example c:\, g:\). However, in rsync syntax, a colon in a path means searching for a remote host.

Solution: use absolute path 'a la unix', replace backslashes (\) with slashes (/) and put /cygdrive/ in front of the drive letter.

Example:

C:\WORK\* –> /cygdrive/c/work/*