1 
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TABLE 6. Location of Species 
The median day of occurrence is not necessarily the peak density loca¬ 
tion; however, for the most part it agrees closely with day of max. lin. 
density. This table shows a reasonable transition from temperate to sub¬ 
tropical to tropical elements of the avifauna. 
TABLE 7» Range of Species 
An attempt is made to arrange the species according to restrictedness 
or broadness of range. The number of days of spread was determined by the 
number of days from first to last sighting. It is not a reliable indicator 
of broadness of range because it cannot account for ranges extending past 
either extreme. It is however useful in estimating some cases of "rareness," 
and does provide a measure of discontinuity. If the days spread figure is 
larger than the days seen figure, the difference is the relative amount of 
discontinuity. Sabines Gull, Dark-rumped Storm Petrel, Jaegers, and Red¬ 
billed Tropicbirds have discontinuity differences of 5 days or more in this 
instance. This should be interpreted as meaning these birds probably occur 
over at least all the indicated spread but are variable or so low in num¬ 
bers that they are often not seen. 
Starting with the assumption that one or more ecological zones were 
crossed, I attempted to determine where it or they were located as re¬ 
flected by changes in the bird populations. If hypothetical ecological 
zones did exist they could be most easily delimited by locating their 
boundaries — where they come together. At these boundaries I further 
hypothesized the following: l) new (southern) species would appear; 2) 
linear density would increase; 3) daily species total would increase; and 
4) northern species would disappear. 
TABLE 8. Chronological Occurrence of Species 
This table lists the day each species was seen. Appearances and disap¬ 
pearances were arbitrarily weighted according to importance as measured by 
the overall linear density• 
TABLE 9 « List of Species by Relative Importance 
Primary species were weighted at 5 units, secondary at 3 units, and 
tertiary at 1 unit. 
TABLE 11. Ecological Boundaries of Species 
The weighted totals of appearances and disappearances for each day are 
shown in Table 11. The linear density for each day was assigned as positive, 
if higher than the median and as negative, if lower than the median, A com¬ 
parison of the four columns revealed the four hypothesized boundary condi¬ 
tions were met on three occasions as indicated by brackets In Table 11. In 
spite of the highly artificial nature of the approach, comparison of these 
three areas with current charts showed that ocean features at the same loca¬ 
tions were in transition states, and a positive correlation was obtained. 
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