Mockingbird flush distances when approached by humans of differing threat levels

These data show flush distances of incubating female mockingbirds on the
University of Florida campus (Gainesville, FL) when approached by four
different humans, each posing a different level of threat to the
bird.  Column A (Nest Location) describes the location of each
nest. Multiple rows for the same nest indicate approaches by different
humans and/or on different days.  Column B (Visitor Type)
indicates the classification (experimental treatment) of the human. The
threat level of that human is provided in Column J (Threat Ranking, which
ranges from 2 [high] to 5 [low]).  An “Intruder” approached the
nest on 4 sequential days and placed one hand on the rim of the nest for
15 seconds before retreating.  Mockingbirds quickly learned to
recognize them and thus Intruders have the highest threat ranking
(2).  An “Associate” approached the nest alongside the Intruder
but stopped 3m from the nest and waited there until the Intruder returned
from the nest. The Associate and Intruder stood facing each other for 15
sec before departing from the nest. Associates had a medium threat ranking
(3).  A “Bystander” approached alone on four consecutive days,
stopped 3m from the nest and stood quietly without looking at the female
for 10 min before departing. Females did not flush during these trial
sessions and hence flush data and behavioral data are not provided.
However, the Bystander approached the nest and placed one hand on the lip
of the nest for 15 seconds on the last day of trials, forcing the female
to flush; results from those trials (one per female) are shown. Bystanders
had a low threat ranking (4) because they typically didn’t threaten the
nest.  Finally, a Control individual who the female had never
seen approached the nest on the last day of trials and placed one hand on
the lip of the nest for 15 seconds.  Control individuals had the
lowest threat ranking (5). Column C indicates the human’s distance from
the nest when the female flushed upon approach.  All humans
started to approach the nest from ~30m and walked towards it at a speed of
~1m/sec. Columns D through I provide behavioral data of the female and her
mate (who sometimes wasn’t present; see column M). Female and male
mockingbirds cannot be distinguished. Hence data in columns D through I
are summed for whatever bird or birds were responding.  Column D
shows the number of times birds hovered over the head of the human. Hovers
were brief, typically <3 sec, and often ended in a “swoop” (Column
E) or an “attack” (Column G). An attack was defined as a downward flight
to within 1m of the human. A swoop was a downward flight toward the human
but not to within 1m.  Column F (“indirect flights”) shows the
number of flights over or around and within 5m from the human, typically
from one perch to another.  Column H shows the time of the first
alarm call in minutes and seconds from the time the human started to
approach the nest.  Column I shows the total number of alarm
calls from the start to finish of the trial. Column K provides an estimate
of human activity near the nest (the number of humans who walked within 5m
of the nest in a 10 min period). Column L indicates an irregularity with a
trial (0 = protocol tightly followed; 1 = protocol not tightly followed or
a problem outside of investigators’ control). Column M provides
miscellaneous notes. Data on presence of the male was inconsistently
taken.