Random Routes for MBBS

MBBS routes are positioned without reference to known birding "hot spots"!   They are intended to provide an unbiased record of bird populations.   And they can lead to unexpected discoveries!

  • Routes for Orange County were selected randomly within some limits.   Technically, they are a stratified random sample.  The County was divided into sixths, and a random point was selected in each sixth.

    Then, in each sixth of the county, a route was identified that fit these criteria . . .

    1. the route must stay on secondary roads (neither NC nor US routes) as much as possible
    2. it must pass through the random point (or as close to it as possible)
    3. it must maintain a NE-SW or NW-SE alignment (chosen randomly) as far as possible

    Then a second random point was selected in each sixth of the county.   A second route was identified that fit the same criteria, except that it included the second random point and it maintained a direction perpendicular to the first route.

    Each route was named after its starting point.

    Some routes pass through suburban or urban areas -- it is important to survey these habitats too!

  • Routes for Chatham County were selected in the same way -- with one modification.   Each route started at a random point (rather than included a random point).   If a route hit the county boundary, it reflected (like a ray of light) back into the county.

    Two routes were added (bringing the total to 14) in order to fill conspicuous gaps in the random sampling (even stratifying the county into sixths left some big holes in the sampling!).

  • Routes for Durham County were selected in the same way that Chatham County routes were selected -- except that there was no need for more than eight routes.