These graphs show the total number of individuals of
each species recorded on all routes in one county
in each year.
Each species has a four-letter code
first two letters of its first name and the first
two letters of the its second name (for instance,
EABL for Eastern Bluebird).
Some species show trends (either upward or
downward) in their numbers over the period of the
surveys. A straight line on a graph
indicates a trend that is statistically significant
(not likely to be an erroneous conclusion) or
almost statistically significant.
A double asterisk in the upper right corner
of a graph indicates a highly significant trend (with a
probability of error less than 1%).
A single asterisk in the upper right corner
indicates a significant trend (with a probability
of error less than 5% but greater than 1%).
A line but no asterisk indicates a
possible trend (with a probability of error less
than 10% but greater than 5%).
For more information about the N. C. MBBS, see the
For a list of the species (with four-letter codes), see
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