The highest priority
species for migration monitoring are those species that breed mainly in
areas where they are not adequately covered by breeding ground surveys
such as the Breeding Bird Survey. A secondary consideration is whether the
species winter mainly south of the United States, and hence cannot be
surveyed by winter surveys such as the Christmas Bird Count. On this
basis, species in categories A-D are all important for migration
monitoring, with species in category A the highest priority. The
categories are defined as follows:
A. Species with
<50% of North American (Canada & U.S. only) breeding range covered
by BBS, and <60% of their winter range in U.S. and Canada.
B. Species with
<50% of North American breeding range covered by BBS, but >60% of
their winter range in U.S. and Canada.
C. Species with
<60% of their Canadian & Alaskan breeding range (but >50% of
North American range) covered by BBS, and <60% of their winter range in
U.S. and Canada.
D. Species with
<60% of their Canadian & Alaskan breeding range (but >50% of
North American range) covered by BBS, but >60% of their winter range in
U.S. and Canada.
E. Species with
>60% of both their Canadian and North American breeding range covered
by BBS, and <60% of their winter range in U.S. and Canada.
F. Species with
>60% of both their Canadian and North American breeding range covered
by BBS, and >60% of their winter range in U.S. and Canada.
X. Resident
landbirds that are considered to be unsuitable candidates for migration
monitoring.