R. Terry Bowyer, Janet L. Rachlow, Kelley M. Stewart & Victor Van Ballenberghe
(2011): Vocalizations by Alaskan moose: female incitation of male aggression.
Behav. Ecol. Sociobiol. 65 (12), 2251-2260.
Abstract: Evidence of female fomentation of male–male aggression as a mechanism
of mate choice is rare, especially in mammals. Female choice of mates in
polygynous species may be masked by intense male competition or by males
attempting to restrict female choice. We studied protest moans of female
Alaskan moose Alces alces gigas in interior Alaska, USA, from 1987 to 1990, to
determine if moans incited male–male aggression. Alaskan moose exhibit a mating
system in which one dominant male (the harem master) herds, defends, courts,
and attempts to mate with females in his harem. Protest moans were given by
females only in response to courtship. We hypothesized that if protest moans
were related to females reducing harassment and exercising mate choice, females
should give protest moans more frequently when courted by small males and less
often when courted by large males, and that rates of male–male aggression would
be elevated following protest moans. Harems were composed of one large male,
with a mean of 4.4 females (median = 3 females); 10% of 132 harems included ≥10
females. The temporal pattern of protest moans from late August through
November was associated with, but tended to lag behind, mating behavior. The
rate of protest moans given by females decreased with increasing size of males
courting them. Male–male aggression was significantly less during periods
without protest moans than during periods in which protest moans occurred.
These results indicate that female moose gave protest moans to reduce
harassment by smaller males, and assure a mating opportunity with the most
dominant male. Such a subtle mechanism of indirect mate choice by females may
occur in other vertebrates in which choice is limited by a mating system in
which male–male combat and male dominance over females reduces opportunities
for female choice. The importance of female choice may be undervalued in
studies of sexual selection in mammals.
URL: http://www.springerlink.com/content/u4765576363t1107/
For reprints please contact R. T. Bowyer (email:
Nathan W. Bailey (2011): ate choice plasticity in the field cricket
Teleogryllus oceanicus: effects of social experience in multiple modalities.
Behav. Ecol. Sociobiol. 95 (12), 2269-2278.
Abstract: Social experience can elicit phenotypically plastic changes in mate
choice, but little is known about the degree to which social information from
one modality can influence mating decisions based on information from a
different modality. I used the field cricket Teleogryllus oceanicus to test
whether experience of chemical cues mimicking a high density of sexually mature
males causes changes in mate choice based on acoustic signals. T. oceanicus
males produce long-range calling songs to attract females for mating, but they
also produce waxy, non-volatile hydrocarbons on their cuticle (CHCs) which,
when deposited on a substrate, can be detected by females and may provide
demographic information. I manipulated female experience of substrate-bound
male CHCs and then performed acoustic mate choice trials. When CHCs were
present on the substrate during trials, females showed greater motivation to
respond to male calling song. This effect diminished with repeated exposure to
male songs, demonstrating that the importance of olfactory cues in altering
acoustic mate choice decreased with increasing exposure to acoustic signals.
However, the temporal nature of CHC experience mattered: previous experience of
CHCs did not alter subsequent female choice for male calling song traits.
Exposure to male song increased the threshold of mate acceptance over time, and
individuals varied considerably in overall levels of responsiveness. Taken
together, the results demonstrate that mate choice is dependent on social
context mediated by multiple modalities in T. oceanicus, but they do not
support the idea that prior experience of social cues in one modality
necessarily influences later mating decisions based on other signalling
modalities.
URL: http://www.springerlink.com/content/b2035275lr665r5g/
For reprints please contact N. W. Bailey (email:
Frans A. Juola & William A. Searcy (2011): Vocalizations reveal body condition
and are associated with visual display traits in great frigatebirds (Fregata
minor). Behav. Ecol. Sociobiol. 95 (12), 2297-2303.
Abstract: Acoustic displays are known to advertise aspects of male quality and
to affect female choice of mates in a variety of birds, including not only
songbirds but some seabirds as well. Male great frigatebirds (Fregata minor)
produce a rapid warble vocalization that forms a prominent part of their
courtship display. We investigated the relationships between aspects of this
vocalization and male quality and pairing success in 103 great frigatebirds
from a population in the northwestern Hawaiian Islands. We found that across
males, frequency bandwidth of the display was negatively related to repetition
rate, enabling us to use deviation from the upper bound regression of bandwidth
on rate (“vocal deviation”) as one measure of vocal performance. We used vocal
consistency, defined as the coefficient of variation of the time interval
between successive peaks in the warble, as a second measure of performance.
Vocal deviation was significantly positively associated with body condition of
male great frigatebirds, but vocal consistency was not. We found that peak
frequency of the warble was not significantly associated with body size but was
negatively associated with size of the gular pouch, the most prominent visual
ornament. Male great frigatebirds showed significant individual differences in
all three vocal measures—peak frequency, vocal deviation, and vocal
consistency—but none of these measures was a significant predictor of pairing
success in our study population. These results suggest that vocalizations
provide honest information about male body condition and gular pouch size in
great frigatebirds but do not influence male success in pairing with females.
URL: http://www.springerlink.com/content/q0w33143kg8m6760/
For reprints please contact Frans A. Juola (email:
Kind regards
Sonja Amoser
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Dr. Sonja Amoser
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3400 Weidlingbach
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