Alarm Call of the Pygmy Rabbit (Brachylagus Idahoensis)

Great Basin Naturalist

Volume 41 Number 1 Article 9

3-31-1981

Alarm call of the pygmy rabbit (Brachylagus idahoensis)

Jeffrey S. Green Brigham Young University

Jerran T. Flinders Brigham Young University

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Recommended Citation Green, Jeffrey S. and Flinders, Jerran T. (1981) "Alarm call of the pygmy rabbit (Brachylagus idahoensis)," Great Basin Naturalist: Vol. 41 : No. 1 , Article 9. Available at: https://scholarsarchive.byu.edu/gbn/vol41/iss1/9

This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. ALARM CALL OF THE PYGMY RABBIT {BRACHYLAGUS IDAHOENSISy

Jeffrey S. Green^'"^ and Jerran T. Flinders^

Abstract.— An alarm vocalization was identified in the pygmy rabbit. The call was composed of from one to seven syllables uttered in rapid succession. The syllables were complex tones with many overlying frequencies; the strongest occurred close to harmonic intervals at 4000 and 6000 Hz. In both laboratory and field conditions, the call seemed to be elicited by a potential predator and its use may be unique among leporids.

Squeals or distress calls reportedly were Alarm calls given by three caged pygmy made by several leporids including the bru.sh rabbits as they were frightened into their den rabbit (Sylvilagus bachmani) (Chapman and box were recorded at 19 cm/sec (range Verts 1969), the New England cottontail (S. 40-20,000 Hz) with a Uher 4000-L tape re- transitionalis) (Olmstead 1970), the desert corder and a Uher M 517 microphone cottontail (S. audubonii) (Orr 1940 and Ingles mounted in a 60-cm-diameter parabolic re- 1941), and the eastern cottontail (S. florid- flector. Recordings were analyzed with a anus) (Marsden and Holler 1964). These calls Uher 4000-L recorder and a Kay 6061B generally were given by wounded rabbits or Sona-graph Spectrum Analyzer (range in response to human handling. In addition, 85-16,000 Hz) with a narrow band (20Hz) Marsden and Holler (1964) identified an filter. (Mention of a trade name, proprietary "alert call" given in response to danger by product, or specific equipment does not con-

swamp rabbits (S. aquaticus) in a confined stitute a guarantee or warranty by the U.S. population. We describe an alarm vocaliza- Department of Agriculture and does not im- tion given by the pygmy rabbit (Brachylagus ply its approval to the exclusion of other idahoensis) (Green and Flinders 1980a). products that may be suitable.) Alarm signals given by Leptis spp. (King- Seven recorded alarm vocalizations, three dom 1974), the European rabbit {Oryctolagus single, and four double syllables (two with cuniculus) (Mykytowycz 1968), and the squeaks) from an adult male rabbit were ana- desert cottontail (Orr 1940) usually were lyzed. All syllables were similar; the strongest made by thumping the ground with the hind fundamental frequency was about 1350 Hz feet. Alann spread quickly among jackrabbits and lasted about 0.1 sec (range 0.09-0.12 (L. californicus) when one of them sat up sec). The mean elapsed time between the with ears erect (Lechleitner 1958). The desert double syllables was 0.32 sec (range cottontail also used its tail as an alarm signal 0.28-0.39 sec). The syllables were complex (Chapman and Willner 1978). When the tail tones with many overlying frequencies; the was raised showing maximum white, con- strongest occurred close to harmonic inter-

specifics fled to cover. vals at 4000 and 6000 Hz (Fig. 1) and extend- The pygmy rabbit lacks white flagging on ed above the 16,000 Hz limit of the sona- the ventral surface of the tail and may have graph. The vocal pattern of each syllable developed a different strategy to signal differed but often contained a rapid rise and alarm. At the U.S. Sheep Experiment Station fall, producing a "blip." The squeaks at the in southeastern Idaho, these rabbits selected end of two double-syllable calls were of short dense brushy habitat (Green and Flinders duration (0.04 sec) at a frequency of about 1980b), where visual signals of alarm would 1460 Hz. Elapsed time between final syl- not be as functional as a vocalization. lables and squeaks was 0.90 sec each.

'This study was supported by USDA Western Regional Federal Cooperative Agreement 12-14-5001-264. ^Department of Botany and Range Science, Brigham Young University, Prove, Utah 84602. 'Present address: U.S. Sheep Experiment Station, Dubois, Idaho 8342.3.

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March 1981 Green and Flinders: Pygmy Rabbit Alarm Call 159

it often utters a faint squeak of The alarm call was composed of from one closely, also noted the first two to seven syllables (usually one or two) uttered fright." Wilde (1978) distress cry of rab- in rapid succession often followed by one to of these calls. The pygmy bits (the loud quavering squeal described by several squeaks. It was heard numerous times occurred when they were re- in natural habitat of pygmy rabbits during all Janson, 1946) seasons of the year. Generally, the call was moved from wire traps and particularly when they were snared (Green and Flinders 1979). given by a rabbit as it retreated into a burrow. Calling often continued for several sec- We presume that the "squeak of fright" (Jan- onds within the burrow and could be heard son 1946) may be a faint distress cry or a part by an observer 15 m away. Rabbits that wait- of the alarm call. Rabbits occasionally after they entered a burrow or den ed until they were in burrows to vocalize squeaked behavioral significance of this is would be less vulnerable to common pre- box, but the pikalike call we dators in the area, coyotes {Canis lairans) and unknown. The (Janson 1946) call similar to the red fox {Vulpes vulpes), but would increase assume to be the alarm and Holler their inclusive fitness (Dunford 1977). One alert call described by Marsden for confined swamp rabbits. rabbit gave the call while it stood in an erect, (1964) female pygmy rab- alert position near a burrow entrance; when In cages, both male and bits frequently gave alarm vocalizations. approached by an observer, it entered the vocal than females, burrow and gave the call again. Another, Males were perhaps more regularly emitted the confined in a live trap, called repeatedly as and certain males an observer approached. alarm call as they dashed to their den box. In conditions, the call Janson (1946:75) noted: "Like other rab- both laboratory and field to be elicited by a potential predator. bits, the pygmy has a loud quavering squeal seemed when captured. In addition, he sometimes ut- Alarm calls given by marmots {Mamiota cali- ground squirrels ters a call somewhat resembling that of a gata) (Taulman 1977), (Dunford pika, but much fainter. When pursued {Spennophilus tereticaudiis) 1977),

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0. ^^^^™^ I ' • I 0.5 1.0 1.5 2.0

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syllable and (b) double Fig. 1. Sonagraph of a postulated alarm vocalization from the pygmy rabbit: (a) single syllable ending with a squeak. 160 Great Basin Naturalist Vol. 41, No. 1

Chapman, A., and G. R. Willner. 1978. Sijlvilagus prairie dogs (Cynomys ludovicianus) (Smith J. auduhonii. Mamm. Species 106:1-4. et al. 1977), and pikas (Ochotona princeps) Dunford, C. 1977. Kin selection for ground squirrel elicited in situa- (Lutton 1975) were similar alarm calls. Amer. Nat. 111:732-785. tions (also see Harvey and Greenwood 1978). S., T. for Green, J. and J. Flinders. 1979. Techniques A low chucklelike call occasionally was capturing pygmy rabbits. Murrel, 60:112-11.3. emitted when a pygmy rabbit was touched 1980a. Brachylagus idahoensis. Mamm. Species 125:1-4. while in a trap or cage. A hand-raised female 1980b. Habitat and dietary relationships of the pygmy rabbit emitted the chuckle when dis- rabbit. pygmy J. Range Manage. 33:136-142. her box. chuckle to be turbed in The seemed P. P. 1978. Anti-pre- Harvey, H., and J. Greenwood. a protest to the violation of individual dis- dator defense strategies: some evolutionary prob- tance and may have corresponded to the lems. Page 129-151 in J. R. Krebs and N. B. grunt in Lepus (Lechleitner 1958). Some pyg- Davies, eds.. Behavioral ecology, an evolutionary approach. Blackwell Scientific Publications, Ox- my rabbits emitted soft barks while entering ford. or leaving their den boxes when there was no Ingles, L. G. 1941. Natural history observations on the discernible cause for alarm. cottontail. 22:227-250. Audubon J. Mamm. To our knowledge, alarm calling in lepo- Janson, R. G. 1946. A survey of the native rabbits of rids under natural conditions has not been re- Utah with reference to their classification, distri- ported. The adaptive advantages of giving bution, life histories and ecology. Unpublished thesis, Utah State Agricultural College, Logan. alarm calls would be greatest in social set- 103 tings where the likelihood of closely related pp. Kingdom, 1974. East African mammals. Academic individuals responding by flight would be in- J. Press, London. 704 pp. creased (Dunford 1977). Pygmy rabbits are Lechleitner, R. R. 1958. Certain aspects of behavior of associated with sagebrush (Artemisia spp.) the black-tailed jack rabbit. Amer. Midland Nat. habitat (Orr 1940) and are generally aggre- 6:145-155. Lutton, L. M. 1975. Notes on territorial behavior and gated (Green and Flinders 1980b). Janson response to predators of the pika, Ochotona prin- (1946) reported estimates of density for pyg- .56:231-234. ceps. J. Mamm. my rabbits based on burrow counts of 0.7 and Marsden, H. M., and N. R. Holler. 1964. Social behav- flush transects of 1.4 rabbits per ha. We ior in confined populations of the cottontail and found densities of 45 rabbits per ha. It is rea- the swamp rabbit. Wildl. Monogr. No. 13. 33 pp. sonable to conclude that alarm calls could be Mykytowycz, R. 1968. Territorial marking by rabbits. Sci. Amer. 218:116-126. selected for this aggregated species living in Olmstead, D. L. 1970. Behavioral comparisons of two a habitat with poor visibility. species of cottontails (Sylvikigus floridanus) and {Sijlvilagus transitionalis). Trans. N.E. Sec. Wild-

life 27:115-126. Acknowledgment Soc. Orr, R. T. 1940. The rabbits of California. Occas. Papers California Acad. Sci. 19:1-227. The assistance of D. E. Miller, Washington S. L. E. C. Oppenheimer, and G. Smith. W. J., Smith, J. State University, who provided the Sona- DeVilla. 1977. Vocalizations of the black-tailed graph Spectrum Analyzer is gratefully ac- prairie dog, Cijnomijs ludovicianus. Anim. Behav. knowledged. 25:152-164. F. 1977. Vocalizations of the hoary mar- Taulman, J. 58:681-683. mot, Marmota caligata. J. Mamm. Llterature Cited Wilde, D. B. 1978. A population analysis of the pygmy rabbit {Sijlvilagus idahoensis) on the INEL site. A., B. Verts. 1969. Interspecific ag- Unpublished dissertation. Idaho State University, Chapman, J. and J. gressive behavior in rabbits. Murrelet 50:17-18. Pocatello. 172 pp.