a) summarized data assembled
by Coomans de Ruiter on the breeding of birds in the lowland of western
Borneo near Pontianak. It appears that the breeding season in that part
of Borneo, and indeed in all of western Borneo (Banks, 1950), starts in
December and reaches a peak in March.

TABLE 3.--Monthly rainfall records, Cocoa Research Station, Quoin Hill.

==============================================================================
Year |Jan. |Feb. |Mar. |April|May |June |July |Aug. |Sept.|Oct. |Nov. |Dec.
------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----
1959 | | | | 6.49|12.16|11.11| 7.64|12.11| 4.75| 8.33|12.10|13.81
1960 | 9.24| 8.17| 3.76|10.65| 8.84|11.00| 6.31|11.25| 8.56| 5.49| 8.39|11.81
1961 | 6.68| 8.06| 4.35| 4.74| 7.55| 7.25| 5.93| 2.40| 7.47| 5.58| 4.38|10.73
1962 | 3.82| 6.76|13.72| 9.68| 6.82| 7.49| 6.59| 5.82| 7.81| 9.47|19.80| 9.28
1963 |21.27| 8.18| 7.64| 0.57| 5.83| 4.62| 0.64|12.49| 5.24| 8.75| 7.43|11.05
1964 | 4.17| 7.92| 4.40|11.20|11.82| 8.04| 2.42| 7.52| 5.69|13.15| 8.82| 9.88
Avg. | 9.03| 7.81| 6.77| 7.22| 8.83| 8.25| 4.92| 8.59| 6.58| 8.46|10.15|11.09
------+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----+-----

Gibson-Hill (1952) has questioned Banks' (1950) interpretation of data
from the egg collection of V. W. Ryves. Gibson-Hill has shown that the
data collected by Ryves covered two widely separated localities, one at
Kiau near Kota Belud and the other near Sandakan. The former locality is
on the west coast of North Borneo and the latter on the east coast of
North Borneo. Gibson-Hill points out, and rightly so, that the timing of
the rainfall in different parts of Borneo must be taken into account
because of the large regional variation. The nesting data from the Ryves
egg collection are scant and when used alone possibly yield a distorted
view of the actual breeding season. Ryves did no collecting in the
Sandakan area between September and March, and in the Kiau area between
May and January. Although the breeding data from North Borneo
accumulated by both Ryves and myself are limited, and records of
rainfall are scant, there appears to be a trend toward breeding after
the heavy rains have fallen.

_Seasonality of breeding in tropical birds._--Possibly Bornean birds
breed mostly in the "driest" part of the year. If so, this is in
contrast with the time of breeding of birds of other tropical areas.
Moreau (1950) found th