as low as the density over the east end of runway 6-24, where the 
shoulders have been leveled for 750 feet from the centerline. 
It is apparent that any killing program, regardless of its 
magnitude, would not result in an effective reduction in albatross 
populations during its first season of operation, and could not come 
even close to eliminating the portion of the population which appear 
in the air over runways in less than 5 or more years. 
Terrain Modification 
: Data gathered during the 1957-58 season have confirmed the 
validity of the conclusions reached during the previous season concern- 
ing the effectiveness of terrain modification as a technique for reduc- 
ing the albatross hazard to aircraft (see Kenyon et al. 1958). 
Index counts of birds soaring over the runways were continued 
throughout much of the 1957-58 season. The counting areas and methods 
were the same as those used during the previous season (Kenyon et al. 
1958) and are not repeated here; the only change was the elimination 
of station 7, as completion of clearing and leveling in the central 
triangle made this station virtually identical with station 6 (fig. 3). 
Albatross soaring in relation to topography.--Albatrosses 
show remarkable adaptation for andskill in utilizing air currents while 
at sea. [t is thus only natural that they make use of any favorable 
air currents while soaring over land on their nesting grounds. This 
' is very obvious even to casual observers. On Sand Island the major 
soaring areas are along the beach dunes, and inland along the edges 
of high ironwood growth, dunes, and revetments, which deflect the wind 
and create updrafts. 
The accompanying map (fig. 3) illustrates the present terrain 
conditions on the runway area on Sand Island. It also shows the major 
flights routes of soaring albatrosses in relation to terrain features. 
These were first determined by general observation, and confirmed by 
runway counts (figs. 4 and 5 and tables 10 and 11). 
The accompanying graphs(figs. 4 and 5) indicate the mean 
number of albatrosses per hour soaring past the counting stations 
during the 1957-58 season. The counts have been broken down into two 
periods: November through January (before the killing program), and 
March through May (after the killing program). However, there is no 
statistically significant difference between the two periods. The 
figures indicate the totals for both species of albatross combined. 
The actual figures on which these graphs are based are presented in 
tables 10 and 11), in which are presented the individual totals for 
Laysan and black-footed albatrosses. Black-footed albatrosses con- 
stituted only 6.4 percent of all albatrosses counted flying over the 
runways. This is explained by their smaller population on the island 
33 

