96 
PACIFIC SCIENCE, Vol. V, January, 1951 
Fig. 3. Adult Lace-necked Dove. Waikii, Hawaii. 
Elevation 4,700 feet above sea level; April 5, 1946. 
abundant food, available either seasonally or 
locally, is primarily responsible for the best 
densities, but the possible factors believed to 
limit high dove populations are different for 
the two zones. Zone C2 lies between 2,500 
and 4,000 feet elevation, where the annual 
mean temperature is 60° F. and the average 
rainfall is between 40 and 60 inches annually. 
This temperature is lower than those in the 
best Lace-necked Dove zones and is sug- 
gested as possibly being able to inhibit high 
populations. Zone Di, occurring between sea 
level and approximately 1,500 feet elevation, 
has an annual mean temperature of about 
73° F. and an annual rainfall with a minimum 
of 60 inches. It is probable that the numerous 
and often heavy rains affect nesting success 
in this zone. 
The poorest dove ranges occur in zones 
D2, D3, El, and E2, which show low percent- 
ages of occupancy (5-21 per cent), poor 
populations (280-1,800), and generally low 
densities (50 or fewer birds per square mile). 
Zone D2 lies between the general elevations 
of 1,500 and 4,000 feet, where the annual 
mean temperature is 60° F. and rainfall 
reaches 450 or more inches annually. Low 
temperatures, heavy rainfall, and the lush 
forest cover all prohibit high densities. Doves 
are found only where suitable foods occur in 
small openings cleared for cultivation or 
resulting from heavy grazing. The other three 
zones, D3, El, and E2, are above 4,000 feet 
elevation, where mean temperatures vary be- 
tween 50° and 40° F. annually, and the ex- 
tremes of rainfall are from about 100 inches 
at lower elevations to less than 40 inches at [ 
higher elevations. The cold temperatures 
probably contribute largely to the prevailing 
poor densities, but at lower elevations (D3) 
the heavy rainfall is another adverse factor. 
Dove foods are extremely limited in these 
zones and water is unavailable in Ei and E2. 
Nearly all informed persons interviewed 
during this survey expressed the opinion | 
that Lace-necked Doves have been decreasing 
in recent years. Many believe that competi- 
tion for food between this species and the 
more plentiful and more recently introduced 
Barred Dove, Geopelia striata striata (L.), is 
the cause of this decrease but data from our i 
food studies given below indicate otherwise. 
It may be significant that on Hawaii, where 
the Barred Dove is just becoming established 
in only a few localized areas, the same island- 
wide decrease of the Lace-necked Dove is 
also reported. 
FOODS j 
An analysis was made of Lace-necked Dove i 
foods from 146 crops and 71 gizzards. Each 
food species in the crop was identified, | 
separated, measured in cubic centimeters, 
totaled by aggregate volume, and recorded |i 
for occurrence. Gizzard contents were identi- ' 
fied and recorded for occurrence only. Every j 
month except January and all islands except j! 
Niihau and Kahoolawe were represented in 
the sample. Except for four doves, all were 
collected between sea level and 2,700 feet 
elevation in zones A, B, Ci, C2, and Di, and " 
