Significant quantitative differences have been detected in fundamental frequency and note
of short calls of pikas (Ochotona princeps) from populations north and south of the Colorado
River in the Rocky Mountains (Somers, 1973) and among populations in the Sierra Nevada of
California, the Wasatch Range of Utah, and the Sangre de Cristo Mountains of New Mexico
(Conner, 1982). In both studies, vocal responses to playback of short calls were measured to
ascertain whether pikas discriminate between calls from their own population and those from
"foreign" populations. The number of vocal responses to playback of short calls were
measured to ascertain whether pikas discriminate between calls from their own population
and those from "foreign" populations. The number of vocal responses to playback of their
own population's call did not differ significantly from playback of calls from playback of calls
from other populations or from control periods of silence during which no calls were played.
These results suggest only that the playback of short calls does not stimulate calling in pikas
as it does in many avian species; they suggest nothing about a pika's ability to discriminate
between short calls from different populations. Another measure of responsiveness is needed
if the ability of pikas to discriminate between structurally different calls is to be rigorously
tested.
The usual response of a pika to a neighbor's short call is to stop what it is doing, look towards
the caller, and resume its activity if no other stimuli (predator, territorial intruder) are present
(Somers, 1973; Conner, 1979). These observations suggest that some measure of attention or
orientation can be used to determine playback discrimination.
The present results demonstrate that pikas are able to discriminate between different
geographic forms of the short call, but why pikas discriminate between local and strange
forms is not clear. It is unlikely that the ability to discriminate differences in call structure
plays a role in assertive mating that reduces gene flow among populations (Baker and
Newaldt, 1978), or in preventing individuals from mating with close relatives (Jenkins, 1978),
as has been suggested for avian song discrimination. The pikas' habitat specificity.
temperature limitations, and risk of predation while off the talus (Smith, 1981) serve as
effective barriers to interbreeding except for populations living very close to one another.
Each population is a separate gene pool and differences in call structure are the result of
independent evolutionary histories.
Strange calls do to appear to carry messages that elicit prolonged orientation and attention
(though pikas are able to hear foreign short calls). Such response specificity (Marler, 1961) is
found in other animal species (Smith, 1977). It seems possible that the limited response of
pikas to strange calls is due to their inability to recognize these calls as those of conspecifics
(or at least sympatric pikas). These strange sounds also do not carry any warning message;
they do not represent a significant event and therefore, do not elicit responses that might
compete with those produced by more important stimuli. Also, by failing to respond, pikas are
able to use time more efficiently, continue ongoing activity without unnecessary disruption,
and maintain a more efficient communication network for both behavioral interactions with
conspecifics and with other sympatric species.
Conner, Douglas A. "Response of Pikas to Playback of Goographic Variations of the Short Call" Journal of Mammalogy, vol. 64, no. 2. 1983,
pp. 336 337.
According to the paper, the authors play a pika short call in order to determine
which of the following?
O Do pikas respond to calls from populations in other locations?
How do pikas respond to a short call warning of danger?
Do pikas use short calls to avoid breeding with close relatives?
