58 
PACIFIC SCIENCE, Vol. XIV, January I960 
TABLE 1 
An Example of the Daily Records and Notes from the Author’s Observation Diary 
OBSERVATION TIME 
6:00-7 :30 a.m. 
11:00-15:00 
16:00-18:00 
Total time: 
7:30 hours 
Number 
AIR TEMPERATURE ( °C. ) 
7-9 
9-11 
7.5-6 
Distance : 
observed 
per hour 
WATER TEMPERATURE (°C) 
4.2-4. 3 
4 
4 
52 miles 
(7 miles) 
Fulmarus glacialis 
3 
51 
10 
TOTAL 
64 
8.7 6 
Oceanodroma furcata 
3 
3 
(white 1) 
7 
(white 1) 
13 
1.78 
O. leucorhoa 
— 
— 
1 
1 
0.13 
Puffinus tenuirostris 
— 
40 
11 
51 
6.98 
Lunda cirrhata 
3 
1 
— 
4 
0.54 
Total 
9 
95 
29 
133 
18.19 
Fur Seal 
1 
— 
— 
1 
— 
Phocaenoides dallii 
— 
about 5 
— 
5 
— 
Date: June 15. Cloudy, occasional fine rain. Air pressure: 1008 mb. 
Wind: E-ESE (1-0), dead calm. 270-200 miles WSW of Attu Is. 
Note: Passed 50° N. latitude, heading toward Attu. Fulmar increased (white one seen at 167° 28' E., 
50° 52' N.) and a flock of P. tenuirostris occurred, flying to E-NE, obliquely against winds. Water tempera- 
ture changed from previous 3° C. to 4° C, with demarcating line NE-SW. 
"economic density” of Elton, which is the density 
of a species when it occurs, calculated by this 
formula: 
5 Number of birds observed per hour 
Number of days the species was observed 
Then, the species’ abundance (general or 
localized distribution) is suggested by the "oc- 
currence rate,” which is: 
Number of days the species was observed 
Total number of observation days 
Therefore, from these formulae, the following 
relation exists between the lowest and economic 
densities: 
lowest density ~ economic density X 
occurrence rate 
The areal relative abundance of sea birds was 
compared by the areal "lowest density” per hour, 
which is: 
2 Number of birds of all the species 
observed per hour 
Number of observation days 
and the "abundance rate of species” was cal- 
culated by: 
Mean number of species which 
was observed per day 
Total number of species observed 
The distributional pattern of species depends 
upon their habits. If systematic areal census 
of the sea birds could be made, they would 
show interesting distributional patterns (Odum, 
1954: 154; Torii, 1952) by species and by sea 
zones. Flocking species, such as shearwaters, 
concentrate in a clustered pattern where food is 
abundant; the phalaropes, which feed on plank- 
ton, show a patchy pattern of small groups; 
while the tufted puffins usually occur at random 
singly or in pairs. Possibly in the case of the 
puffins, a sparse food supply is enough to sus- 
tain their solitary life on the ocean. 
