y
nests for which I have records took from four and one-half to five
days to construct. A four-to five-day period of building is reported
by other observers (Nice, 1929:16; Pitelka and Koestner, 1942:99;
Hensley, 1950:242; Nolan, 1960:230).

One instance of protracted building was recorded. Nest 6-d (1960) was
begun on May 29, 1960, and not completed until nine days later on June
6, 1960. In contrast nest 1-g (1960) begun on May 31, 1960, was
finished three days later on June 2, 1960. Nestbuilding occurs between
the hours of 6:00 a.m. and 5:30 p.m. Heavy rain in the early morning
may delay building.

_Abortive Nestbuilding Efforts_

Eight of 38 nests started in 1960 were never completed (Table 6). Six
of these abortive attempts were abandoned during, or shortly after,
the completion of the suspension apparatus. Five of these nests were
abandoned because the female did not begin building following the end
of work by the male. The early abandonment of the other three nests
1-a (1960), 2-c (1960) and 6-e (1960) was attributable to the
interruption of building by the male because of heavy rain and
protracted territorial conflicts. The occurrence of these abortive
nests at any time within the nesting efforts of a single pair
indicates that such attempts are not examples of "false nestbuilding."

_Renesting_

Renesting after desertion or successful fledging occurs within two to
thirty-six hours. Young were fledged from 1-a (1959) on June 19, 1959,
and nest 1-b (1959) was discovered when late in the second phase of
construction on June 22. If the nest was started on June 20, then
renesting took place within 15 hours after fledging.

_The Nest_

Several authors have described various aspects of the nest of the Bell
Vireo, notably Goss (1891:535); Simmons (_in_ Bent, 1950:256), Nice
(1929:13) and Nolan (1960:230-231). I can add but little to these
descriptions.

The nest itself is a compact structure composed of strips of bark and
strands of grasses that are interwoven and tightly bound with animal
silk. The floor of the cup is first lined with a layer of small leaves
and then the entire interior is lined with fine stems or strips of
bark. Feathers are occasionally used to pad the bottom prior to
lining, as are pieces of wool and milkweed down. Nest 2-e (1960) had
been packed with small pieces of soil bearing moss prior to lining.

TABLE 6. ABORTIVE NESTING ATTEMPTS IN MAY AND JUNE OF 1960.

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