Vera A. Matrosova, Ilya A. Volodin, Elena V. Volodina & Nina A. Vasilieva
(2010): Stability of acoustic individuality in the alarm calls of wild
yellow ground squirrels Spermophilus fulvus and contrasting calls from
trapped and free-ranging callers. Naturwissenschaften, 96 (8), 707-715.
Abstract: The questions of individuality and stability of cues to identity
in vocal signals are of considerable importance from theoretical and
conservation perspectives. While individuality in alarm calls has been
reported for many sciurids, it is not well-documented that the vocal
identity encoded in the alarm calls is stable between different encounters
with predators. Previous studies of two obligate hibernating rodents,
speckled ground squirrels Spermophilus suslicus, and yellow ground squirrels
Spermophilus fulvus demonstrated that, after hibernation, most individuals
could not be identified reliably by their alarm calls. Moreover, in most
speckled ground squirrels, individual patterns of alarm calls changed
progressively over as little as 2 weeks. However, these previous data have
been obtained using the collection of alarm calls from trapped animals.
Here, we examined ten free-ranging dye-marked yellow ground squirrels to
determine whether their alarm calls retain the cues to individuality between
two encounters of surrogate predators (humans), separated on average by 3
days. Discriminant function analysis showed that the alarm calls of
individual yellow ground squirrels were very similar within a recording
session, providing very high individual distinctiveness. However, in six of
the ten animals, the alarm calls were unstable between recording sessions.
Also, we examined ten dye-marked individuals for consistency of acoustic
characteristics of their alarm calls between the encounters of humans,
differing in techniques of call collection, from free-ranging vs trapped
animals. We found differences only in two variables, both related to sound
degradation in the environment. Data are discussed in relation to hypotheses
explaining the adaptive utility of acoustic individuality in alarm calls.
For reprints please contact I.A. Volodin (email:
Alban Lemasson, Karim Ouattara, Hélène Bouchet & Klaus Zuberbühler (2010):
Speed of call delivery is related to context and caller identity in
Campbell?s monkey males. Naturwissenschaften, 97 (11), 1023-1027.
Abstract: Call rate can be a salient feature in animal communication.
Depending on the species, different psychological variables appear to
influence call rates but the exact nature of these relationships remains
poorly explored. Here, we demonstrate for free-ranging Campbell?s monkeys
that the call rates of four different alarm series (termed H, K, K+, and B
series) vary systematically as a function of context, associated behaviour,
and identity of the caller. K+ series were given more rapidly to predation
than non-predation events, K+ and K series more rapidly to visual than
auditory predator detection, and H series more rapidly while
counterattacking an eagle than staying put. Finally, there were individual
differences in B series, suggesting that call rate potentially provides
listeners with cues about the caller?s anti-predator behaviour, event type
experienced, and his identity.
For reprints please contact A. Lemasson (email:
Dr. Sonja Amoser