=======================================
Nest | Length | Cause of abandonment
| of time |
| worked on |
-----+-----------+--------------------------------
1-a | 1 day | Heavy rain
1-h | 2 days | Female failed to build
2-a | 1/2 day | Female failed to build
2-c | 1 day | Protracted territorial dispute
4-a | 1 day | Female failed to build
5-a | 1 day | Female failed to build
6-c | 1 day | Heavy rain
7-a | 2 days | Female failed to build
-----+-----------+--------------------------------

Early nests tend to be bulkier, having thicker walls and bottoms than
later efforts. However, nests in May were found to have 16 per cent
thicker bottoms and 41 per cent thicker walls than nests in June
(Table 7). Standard nest measurements do not show this to be so, for
the exterior and interior diameters at the rim are governed by the
angle between the two branches of the fork.

TABLE 7. DIMENSIONS OF NESTS IN MAY (1960) AND JUNE (1960).

========================================================
Measurements | May (N 10) | June (N 8)
------------------------+---------------+---------------
External depth | 61.6 mm. | 59.3 mm.
Depth of cup | 45.5 mm. | 46.3 mm.
Outside diameter | 57.3/55.5 mm. | 54.3/53.5 mm.
Inside diameter | 43.4/42.2 mm. | 45.5/43.9 mm.
Thickness of forward | |
wall 1 inch below rim | 13.8 mm. | 7.6 mm.
Thickness of bottom | 11.3 mm. | 4.6 mm.
------------------------+---------------+---------------

EGGLAYING AND INCUBATION

_Egglaying_

Egglaying begins the first or second day after completion of the nest.
The female sits in the nest occasionally for periods of five to
twenty-five minutes on the day the nest is completed. This is
interrupted by periods of nest-adornment and foraging; such activities
sometimes keep the female off the nest for several hours. Prior to the
laying of the first egg, only the female is seen on the nest,
although the male is often seen sitting quietly within the nest tree a
few feet from the female. The infrequency of the "congested" song and
the alarm (_eh-eH-EH_) after the inception of "broodiness" indicates
the waning of courtship behavior. As later in incubation only the
"normal" song and the scold are heard.

Eggs are laid early in the morning prior to 5:30 a. m. according