Behaviour, Volume 141, Number 9 (September 2004)
<a
href="http://ariel.ingentaselect.com/vl=950353/cl=126/nw=1/rpsv/cw/www/brill/00057959/v141n9/contp1-1.htm";
rel="nofollow">http://ariel.ingentaselect.com/vl=950353/cl=126/nw=1/rpsv/cw/www/brill/00057959/v141n9/contp1-1.htm</a>
(Abstracts below)
----------------
Trillmich, J, C Fichtel & PM Kappeler (2004) Coordination of group movements
in wild Verreauxs sifakas (Propithecus verreauxi). Behaviour 141: 1103-1120.
Collias, NE & EC Collias (2004) Comparison of vocal signals of three species
of African finches. Behaviour 141: 1151-1171.
Busch, DS & JCT Wingfield (2004) Territorial aggression of a tropical
passerine, Zonotrichia capensis, in response to a variety of conspecific
intruders. Behaviour 141: 1173-1188.
------------
Trillmich, J, C Fichtel & PM Kappeler (2004) Coordination of group movements
in wild Verreauxs sifakas (Propithecus verreauxi). Behaviour 141: 1103-1120.
Abstract: Maintenance of group cohesion is of vital importance for
group-living species. Individuals therefore need to coordinate their
potentially divergent interests to maintain group cohesion. We studied
behavioural aspects and mechanisms of coordinated group movements in
Verreaux's sifakas (Propithecus verreauxi), an arboreal Malagasy primate
living in small groups. During a field study in Kirindy forest, western
Madagascar, we studied the initiation and course of group movements, as well
as vocalisations used in this context, in three social groups. We found that
both sexes initiated group movements, but females did so more often, lead
groups further and enlisted more followers than males. Sex of the leader had
no effect on the probability that a group would feed or rest after a
successful movement, however. Grumble vocalisations were emitted by both
leaders and followers at high rates, both before and during group
progressions, but Grumbles uttered just before an individual moved were
characterised by a significantly steeper frequency modulation at the
beginning of the call and higher call frequencies in both females and males.
The results of this study indicated that sifakas, which evolved group-living
independently from other primates, converge with many other group-living
primates in several fundamental proximate aspects of group coordination and
cohesion. In contrast to many other primates, however, sifakas did not use a
particular call or other signals to initiate or control group movements.
Collias, NE & EC Collias (2004) Comparison of vocal signals of three species
of African finches. Behaviour 141: 1151-1171.
Abstract: African finches of a monophyletic group in the Passeridae nest in
colonies with roofed nests thatched of dry grass-stems. Vocal signals are
described, with the aid of sonograms, 13 for the white-browed sparrow-weaver
(Plocepasser mahali)(Pm), 13 for the grey-capped social weaver
(Pseudonigrita arnaudi) (Pa), and 20 for the sociable weaver (Philetairus
socius) (Ps). These vocal signals fall into general categories, as is true
for most birds, of alarm calls, agonistic behavior, and courtship and mating
signals, parent-young relations, and flock contact calls. These three
species illustrate the principle of adaptive specialization of vocal
signals. Pm differs from the others in having a loud dawn song, a whispered
version of this song, and also a loud vocalization frequently given in
defense of a group territory within which the birds forage. Pa and Ps differ
from Pm in defending only the immediate vicinity of the nest or nest
chamber, in foraging in large flocks on neutral ground often well away from
the colony nest trees, and have special flock calls. In Pa, the territorial
call is used mainly to announce arrival at its nest, and song is rare or
absent in this species. Ps, which lives in a large, apartmentstyle communal
nest, has the most diversified repertoire, especially of social contact
calls. Convergent evolution of vocal signals and social organization with
unrelated families gives some idea of the selection pressures in the
evolution of these signals.
Busch, DS & JCT Wingfield (2004) Territorial aggression of a tropical
passerine, Zonotrichia capensis, in response to a variety of conspecific
intruders. Behaviour 141: 1173-1188.
Abstract: The expression of territorial aggression by reproductively active,
resident birds varies between the sexes and in response to different
intruder types. Previous studies have predicted that individuals should be
more aggressive towards conspecific intruders of the same sex and tolerate
intruders of the opposite sex and immature individuals. In this study, we
investigated the behavioural responses of a tropical population of
rufous-collared sparrows (Zonotrichia capensis) to a variety of caged
intruder types: Singing Males, Silent Males, Females, and Juveniles. In this
species, territories are used by the resident male and female and their
young, and are also used by floaters - mature individuals that do not hold
territories. Resident males responded similarly and aggressively to all
adult intruders in terms of song number, closest approach to the intruder,
time within 5 m of the intruder, and a composite aggression score. There was
no significant variation in the response of resident females to the
different intruder types, although the strongest responses of the resident
female were to female intruders. Neither resident males nor females behaved
aggressively towards juvenile intruders. These results fail to support the
observational predictions for males and females that individuals should be
most aggressive towards members of the same sex, who pose the greatest
threat in terms of cuckoldry and territorial takeover.
|