Part II

How to use this information for tracking Spring migratory aerofauna

• During Spring Migration, the 1000mb-500mb thickness chart can also be useful to gauge the arrival of aerial insectivores. Specifically, at or near the 5580 meter contour. While other bird species have their spring migratory preferences at different contours, aerial insectivores and wood warblers are correlated with the contours outlined here.
• Often times most tree swallows, bank swallows few of the “cliff swallow scouts” will arrive in the vicinity of the 5460 meter
• You can gauge the arrival of  the bulk of our aerial insectivores between 5530- 5580 meters +/-. This is the boundary where the presence of most flying insects “aeroplankton” are noticeably denser than points north of the contour.   Since aerial insectivores follow the food, all one needs to do is to find the contour that is likely to contain the most flying insects.