scholarly journals The adaptive utility of Richardson’s ground squirrel (Spermophilus richardsonii) short-range ultrasonic alarm signals

2006 ◽  
Vol 84 (9) ◽  
pp. 1322-1330 ◽  
Author(s):  
David R. Wilson ◽  
James F. Hare
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Older Individuals ◽  
Alarm Signals ◽  
Active Space ◽  
Spermophilus Richardsonii ◽  
Ultrasonic Calls ◽  
Audible Alarm ◽  
Signal Type

Richardson’s ground squirrels ( Spermophilus richardsonii (Sabine, 1822)) produce audible (ca. 8 kHz) and (or) ultrasonic (ca. 48 kHz) alarm vocalizations that warn conspecifics of impending danger. Audible calls have a larger active space than ultrasonic calls because they travel farther, are louder, and contain frequencies to which conspecific and allospecific recipients are more sensitive. In our first experiment, we presented an alarming stimulus to 103 squirrels to examine the effect of threat proximity on signal type. The ratio of ultrasonic to audible alarm calls increased with increasing distance from the stimulus. We conclude that the size of the active space influences signalling strategy and that squirrels emitting ultrasonic calls can signal conspecifics to the exclusion of distant predators. As recipients of ultrasonic calls must be close to the signaler, one context in which ultrasonic calling may be most adaptive is during natal emergence when juveniles are particularly abundant, highly vulnerable to predation, and clustered in space. In our second experiment, we broadcast ultrasonic alarm signals to emerging juveniles and found that they, like older individuals, responded to calls by increasing vigilance. We discuss the adaptive utility of multiple signalling strategies in light of our findings.

scholarly journals Geographic variability in the alarm calls of the European ground squirrel

2019 ◽  
Vol 66 (4) ◽  
pp. 407-415 ◽  
Author(s):  
Irena Schneiderová ◽  
Lucie Štefanská ◽  
Lukáš Kratochvíl
Keyword(s):  
Czech Republic ◽  
Ground Squirrel ◽  
Function Analysis ◽  
Mammalian Species ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Geographic Variability ◽  
The Czech Republic ◽  
Spermophilus Citellus ◽  
Different Origins

Abstract Geographic variability in vocalizations has been documented in many mammalian species. We examined to what extent it applies to the alarm calls of the European ground squirrel Spermophilus citellus. We recorded the calls of 82 adult individuals from 5 natural colonies in the Czech Republic and 24 adult individuals from an artificial seminatural colony located in a Czech zoo. The founders of this colony originated from 4 different natural colonies in the Czech Republic. Our results showed that there are hardly any differences in the acoustic structure of the alarm calls between male and female European ground squirrels. Discriminant function analysis showed the highest degree of discriminability for the most isolated sites (54–74% of individuals classified correctly), whereas the lowest degree of discriminability was found for 2 interconnected colonies (38–40% individuals classified correctly). Individuals from the artificial seminatural colony were often classified correctly to this colony (58% classified correctly); however, the precision of the classification was comparatively relatively low, that is, many individuals from other colonies were incorrectly classified into this seminatural colony. This likely corresponds to the different origins of its founders. These findings indicate that there is a rather substantial geographic variability in the alarm calls of the European ground squirrel, and our study highlights its possible impact on conservation measures such as establishing artificial colonies or reintroductions.

Description of Sarcocystis campestris sp. n. (Protozoa: Sarcocystidae): a parasite of the badger Taxidea taxus with experimental transmission to the Richardson's ground squirrel, Spermophilus richardsonii

1983 ◽  
Vol 61 (2) ◽  
pp. 370-377 ◽  
Author(s):  
Richard J. Cawthorn ◽  
Gary A. Wobeser ◽  
Alvin A. Gajadhar
Keyword(s):  
Ground Squirrel ◽  
Prepatent Period ◽  
Ground Squirrels ◽  
Intermediate Hosts ◽  
Patent Period ◽  
Sporocyst Residuum ◽  
Experimental Transmission ◽  
Taxidea Taxus ◽  
Spermophilus Richardsonii ◽  
Large Round

Sarcocystis campestris sp. n. (Protozoa: Sarcocystidae) is an heteroxenous coccidium with badgers (Taxidea taxus) as natural and experimental definitive hosts and Richardson's ground squirrels (Spermophilus richardsonii) as experimental intermediate hosts. Free sporocysts (10.2 × 8.0 μm with a large, round sporocyst residuum consisting of a single refractile granule), obtained from intestinal scrapings of badgers (carcasses frozen 2 years at −20 °C), were orally administered to juvenile Richardson's ground squirrels. Acute fatal sarcocystosis developed in some squirrels at 11–13 days postinoculation (p.i.). Meronts (second generation) were present 9–12 days p.i. in the vascular endothelium of many tissues (especially the lungs). Cysts developed in skeletal muscle, contained metrocytes (7 × 5 μm) 30 days p.i., and beginning 46 days p.i., bradyzoites (12.0 × 3.5 μm) were present. Cysts were macroscopic as early as 258 days p.i. Squirrel carcasses containing cysts (76 days p.i.) of S. campestris sp. n. were fed to Sarcocystis-free badgers. The prepatent period was 9 days and the patent period at least 13 days. Both badgers were ill early in the patent period and passed unformed feces during the patent period. Free sporocysts were 10.2 × 8.0 μm and each had an elongate sporocyst residuum containing numerous small refractile granules.

scholarly journals Richardson's ground squirrels (Spermophilus richardsonii) do not communicate predator movements via changes in call rate

2003 ◽  
Vol 81 (12) ◽  
pp. 2026-2031 ◽  
Author(s):  
David R Wilson ◽  
James F Hare
Keyword(s):  
Ground Squirrels ◽  
Alarm Calls ◽  
Call Rate ◽  
Free Living ◽  
Spermophilus Richardsonii

The call rate of repetitive alarm calls produced by Richardson's ground squirrels (Spermophilus richardsonii) conveys the extent of threat during predator encounters. It remains unknown, however, whether changes in call rate communicate predator movements. That is, does an increasing call rate indicate an approaching predator and a decreasing rate the opposite? We presented free-living squirrels with moving predator models and recorded their responses. Vigilant behaviour increased more when predators approached versus retreated, suggesting that squirrels recognize the changes in threat associated with predator movements. Squirrels rarely produced alarm calls during these encounters, however, suggesting that squirrels do not rely entirely on alarm vocalizations to assess the threat posed by potential predators. Receivers of manipulated calls did not respond differentially to alarm calls containing an increasing or decreasing rate of syllable production. Thus, while rate may encode information about the extent of threat, Richardson's ground squirrels do not communicate predator movements via changes in call rate.

FLEAS (SIPHONAPTERA) ASSOCIATED WITH GROUND SQUIRRELS (SPERMOPHILUS SPP.) IN MANITOBA, CANADA

1990 ◽  
Vol 122 (3) ◽  
pp. 449-458 ◽  
Author(s):  
Terry D. Galloway ◽  
John E. Christie
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Spermophilus Richardsonii ◽  
Eastern Chipmunk ◽  
First Time

AbstractTwenty-one species of fleas, seven of which are considered true ground squirrel fleas, were collected by various means from Spermophilus richardsonii (Sabine), S. tridecemlineatus (Mitchell), and S. franklinii (Sabine) in Manitoba. Opisocrostis tuberculatus tuberculatus (Baker), O. labis (Jordan and Rothschild), Neopsylla inopina Rothschild, and Rhadinopsylla fraterna (Baker) are ground squirrel fleas reported from Manitoba for the first time. These, in addition to Oropsylla rupestris (Jordan) and Thrassis bacchi bacchi (Rothschild), were restricted to the southwestern region of the province, but Opisocrostis bruneri (Baker) was collected throughout the range of the ground squirrels, irrespective of location. Fourteen species collected were considered accidental on ground squirrels, one of which, Tamiophila grandis (Rothschild) (an eastern chipmunk parasite), was recorded for the first time in the province.

Populations of ferruginous and Swainson's hawks increase in synchrony with ground squirrels

1989 ◽  
Vol 67 (10) ◽  
pp. 2596-2601 ◽  
Author(s):  
Josef K. Schmutz ◽  
Daniel J. Hungle
Keyword(s):  
Ground Squirrel ◽  
Prey Density ◽  
Prey Species ◽  
Ground Squirrels ◽  
Crop Damage ◽  
Agricultural Fields ◽  
Fledging Success ◽  
Spermophilus Richardsonii ◽  
Buteo Regalis ◽  
Buteo Swainsoni

We compared changes in the densities of breeding ferruginous (Buteo regalis) and Swainson's hawks (Buteo swainsoni) over a period of 9 years with the abundance of a major prey species, Richardson's ground squirrel (Spermophilus richardsonii). We used the amount of poison distributed by landowners annually in their attempts to reduce crop damage by ground squirrels as an index of ground squirrel abundance. Though ground squirrel abundance was positively correlated with hawk density overall, the hawks differed in their responses to changing prey density. Breeding density and fledging success of the ferruginous hawk, a food specialist, were consistently correlated with squirrel abundance. The density of Swainson's hawks increased only where grassland was interspersed with agricultural fields. Fledging success of Swainson's hawks was not correlated with ground squirrel abundance. We suggest that the availability of small prey in spring affected breeding dispersion and reproductive success of Swainson's hawks.

scholarly journals Individual-based acoustic variation of the alarm calls in the long-tailed ground squirrel

2021 ◽  
Vol 8 (2) ◽  
Author(s):  
Denis Goncharov ◽  
Richard Policht ◽  
Lucie Hambálková ◽  
Viktor Salovarov ◽  
Vlastimil Hart
Keyword(s):  
Individual Variation ◽  
Ground Squirrel ◽  
Function Analysis ◽  
Individual Variability ◽  
Ground Squirrels ◽  
Alarm Calls ◽  
Phylogenetic Position ◽  
Vocal Individuality ◽  
The Individual ◽  
Acoustic Variation

Based on their phylogenetic position, Nearctic ground squirrels are closest relatives to the long-tailed ground squirrel Urocitellus undulates even though it has Palaearctic distribution. We aimed to investigate the variability of alarm calls of the long-tailed ground squirrel to test the individual variation in alarm calls. This species is known to produce two types of alarm calls: whistle alarms and wideband calls. Although ground squirrels are a model group for the study of vocal individuality, this phenomenon has not yet been studied in a species producing two such completely different types of alarms. Most of ground squirrel species produce either whistle or wideband alarms and this species represents a unique model for testing the degree of individual variability depending on completely different acoustic structures. We analysed 269 whistle alarms produced by 13 individuals and 591 wideband alarms from 25 individuals at the western part of Lake Baikal. A discriminant function analysis (DFA) assigned 93.5% (88.9%, cross-validated result) of whistle alarms to the correct individual and 91.4% (84%) of wideband alarms. This is the first evidence of individual variation in wideband alarms compared with whistle alarms and occurrence of vocal individuality in two warning signals of a completely different acoustic structure produced by a ground squirrel.

Repetitive calls of juvenile Richardson's ground squirrels (Spermophilus richardsonii) communicate response urgency

2001 ◽  
Vol 79 (4) ◽  
pp. 569-573 ◽  
Author(s):  
Kurtis J Warkentin ◽  
Annika TH Keeley ◽  
James F Hare
Keyword(s):  
Ground Squirrel ◽  
Ground Squirrels ◽  
Call Rate ◽  
Spermophilus Richardsonii ◽  
Predator Model ◽  
Antipredator Calls

Richardson's ground squirrels, Spermophilus richardsonii, produce both repetitive and non-repetitive antipredator calls. While many hypotheses have been advanced to explain non-repetitive calls, the function of repetitive calling has received relatively little attention. We presented juvenile Richardson's ground squirrels with a predator model at distances ranging from 1 to 8 m and recorded the subsequent repetitive calls on digital audiotape. The rate of calling was inversely correlated with the distance between the model and the caller, with distance explaining almost 24% of the variation in call rate. To determine whether call recipients use that information, we manipulated the intersyllable latency of a single repetitive call exemplar to form 3 test stimuli varying only in call rate. Across 16 Richardson's ground squirrel colonies to which these calls were broadcast, the proportion of squirrels assuming the highly vigilant, alert posture increased with the rate of the repetitive call presented. Hence, juvenile Richardson's ground squirrels appear to communicate the proximity and presumably the degree of threat posed by potential predators.

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