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exhaustion or reduced motivation. The males that showed less drift, sang longer
strophes, and had a longer song repertoire are considered the “better” singers.
Poesel et al. (
2001
) have studied the song patterns at dawn in 20 blue tit males,
demonstrating that its song output, more than song complexity, is a trait connected
with sexual selection. In fact, males with a higher song output without drift were
found to participate in pairs in which females started laying earlier and laid larger
clutches.
Experimental manipulation of the dawn and dusk chorus in the common black-
bird (
Turdus merula
) conducted by Cuthill and Macdonald (
1990
) has demonstrated
that both the nutrition status of the male and his fertility affect the timing and
intensity of the dawn and dusk chorus. Providing supplementary food has produced
in paired males an earlier song activity: they sang longer and at higher peaks at
dawn and dusk. Close to their fertility peak, males start to sing early, and the song
has longer duration at dusk and dawn.
Dawn is a period in which birds utilizing the song as an honest signal of male
quality transmit such information to females. This point has been confirmed by
Murphy et al. (
2008
) studying the eastern kingbird (
Tyrannus tyrannus
) (Fig.
7.5
).
In this species a distinctive song is sung at dawn. Morphological character and song
complexity were correlated. Earlier singing males had larger and longer flight
feathers, and they sang at high rates. Early-singing males were mated with
earlier-breeding females.
The dawn chorus in the nightingale (
Luscinia megarhynchos
) remains largely
constant during the breeding season, confirming that at least in this species the dawn
song has the function of defending territory and is not used by males to attract
females. In fact if the song of the male was utilized to maximize pair formation, we
would expect variation in the singing performance before and after the mating
period, but this has not observed, as reported by Kunc et al. (
2005
).
The song rate and the proportion of whistle songs were found to be low at the
beginning of the reproductive season and cannot be used to predict the mating
status. The male performance remained stable also after the arrival of females.
Synchronous and alternating choruses are common in insects and anurans. The
interindividual interactions between contemporary calling males generate
epiphenomena of synchronization or alternation (Greenfield
1994
). Ignoring the
farthest individuals may represent a trade-off strategy to reduce a too demanding
alternation.
In many birds song is a communicative signal used for multiple purposes such as
like territorial defense or female attraction. The song activity of the chiffchaff
(
Phylloscopus collybita
), a small songbird of the Palearctic region, has been
investigated by Rodrigues (
1996
) in southeastern England (Wytham Woods,
Oxford). Despite evidence from other species, the chiffchaff did not sing more
during the fertile period of the female, and the song rate maintained constant during
egg deposition and nestling feeding. Probably the male continues to sing to attract a
secondary female or neighboring female searching for an extra-pair copulation.
This species sings after 30 min from dawn but it sings more during the post-fertile
period than at other stages, and this contradicts the “announcement hypothesis” of
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