Caracal caracal (Schreber, 1776) is a felid commonly called the caracal. It is a slender, medium-sized cat (5.8–22 kg) characterized by a short tail and long ear tufts. C. caracal has a wide distribution and is found throughout Africa, north to the Arabian Peninsula, the Middle East, central and southwest Asia into India; its habitat includes arid woodlands, savanna, scrublands, hilly steppes, and arid mountainous regions. It is globally listed by the International Union for Conservation of Nature and Natural Resources as “Least Concern” despite population trends unknown across most of its geographic distribution. The Convention on International Trade in Endangered Species of Wild Fauna and Flora lists Asian populations under Appendix I and African populations under Appendix II.
In many species, territory advertisement is thought to be one of the primary functions of acoustic communication. North American red squirrels are a territorial species in which ‘rattles’ have long been thought to be the principal signal communicating territory ownership. These vocalizations have been assumed to deter intruders, thus reducing energetic costs and the risk of injury associated with direct aggressive interactions. However, this hypothesis has not been directly tested. Here we used a speaker occupation experiment to test whether red squirrel rattles function to deter conspecific rivals. We studied 29 male squirrels and removed each individual from his territory twice in a paired design. During the experimental treatment, we simulated the owner’s presence after its removal by broadcasting the owner’s rattle from a loudspeaker at the centre of the territory once every 7 min. During the control treatment, the territory was left in silence following the temporary removal of the owner. We found that the presence of a speaker replacement reduced the probability of intrusion by 34% and increased the latency to first intrusion by 7%, providing support for the hypothesis that rattles play an active role in reducing intrusion risk. However, intrusions were not completely averted by the speaker replacement, indicating that for some individuals vocalizations alone are not a sufficient deterrent without other cues of the territory owner.
19In many species, territory defense is thought to be one of the primary functions of acoustic 20 communication. North American red squirrels are a territorial species in which 'rattles' have long 21 been thought to be the principal signal communicating territory ownership. These vocalizations 22 have been assumed to deter intruders, thus reducing energy costs and the risk of injury associated 23 with direct aggressive interactions. However, this hypothesis has not been directly tested. Here we 24 used a speaker occupation experiment to test whether red squirrel rattles function to deter 25 conspecific rivals. We studied 29 male squirrels and removed each individual from his territory 26 twice in a paired design. During the experimental treatment we simulated the owner's presence after 27 its removal by broadcasting the owner's rattle from a loudspeaker at the center of the territory once 28 every seven minutes. During the control treatment the territory was left in silence after the 29 temporary removal of the owner. We found that the presence of a speaker replacement reduced the 30 probability of intrusion by 34% and increased the latency to first intrusion by 7%, providing support 31 for the hypothesis that rattles play an active role in reducing intrusion risk. However, intrusions 32 were not completely averted by the speaker replacement, indicating that vocalizations alone are not 33 sufficient without other cues of the territory owner. 34 2 35 Keywords 36 mammalian vocalizations, acoustic communication, territoriality, speaker occupation, red squirrel 37 38 39 Vocal communication is thought to have several principle functions, including territorial 40 defence (Catchpole, 1982; Catchpole & Slater, 1995; Bradbury & Vehrencamp, 2011). While the 41 role of vocalizations in repelling conspecific rivals is typically well accepted, this function has 42 rarely been directly demonstrated. Evidence supporting the functionality of vocalizations as a 43 deterrent for intruders has come mostly through indirect means, via observational and correlational 44 studies in the field, rather than direct experimental tests of functionality. For example, vocalizations 45 commonly observed in association with intrusion events or aggressive interactions among 46 61 2008). By inducing an aggressive reaction in territory owners, the use of playbacks can effectively 62 demonstrate that vocalizations function in immediate territorial confrontations. However, by 63measuring the response of owners, rather than intruders, these studies fail to clarify whether 64 vocalizations induce avoidance and function to keep conspecifics off the territory, even when 65 confrontations are not imminent. 66Muting and speaker occupation are two experimental designs that have been used in 67 songbirds to test the hypothesis that acoustic signals function to deter territory intrusions. In muting 68 349 long-term access to her trapline. A special thank you to J. Robertson and S. Sonnega for assistance
Alien species can affect native species through several ecological processes such as competition. Here we tested the hypothesis of interspecific competition for space and food resources between the native Eurasian red squirrel and the invasive Pallas’s squirrel introduced in Italy. We used an experimental study design comparing space and habitat use and body condition parameters of red squirrels between areas of co-occurrence with the Pallas’s squirrel and areas without it. There were no differences in mean home range size of red squirrels between red-only areas and red-Pallas. However, when Pallas’s squirrels were removed, the red squirrels increased their home ranges. Moreover, in the area of syntopy, red squirrels had a higher degree of intraspecific home range overlap than in the red-only area. We also found indirect evidence for competition for food with red squirrels having a poorer body condition when co-occurring with the alien species. We analyzed the body mass and size of red squirrels in the two areas and our results showed that red squirrels had a reduced body mass and size when in syntopy, confirming that the interspecific competition does not allow red squirrels to reach the optimum body condition that they would have if the competitor was not present. Moreover, tree-species niche overlap was very high and both species fed primarily on the same tree seeds. Differences in vegetation cover between areas are discussed. This is the first study that confirms the invasiveness of the Pallas’s squirrel also in terms of capability to compete with native species
Drought, past fire suppression, insect invasion, and high-severity fire represent a disturbance cascade characteristic of forests in the western United States. The result is altered forest ecosystems diminished in their function and capacity to support biodiversity. Small habitat specialists are particularly vulnerable to the impacts of disturbances because of their limited movement capacity and high site fidelity. Research suggests that small mammals suffer limited direct mortality from fire but are increasingly vulnerable to local extirpation because of secondary impacts that include habitat loss and reduced food availability, survival, and reproduction. We examine the direct and secondary impacts of increasingly severe fire events on the endangered Mt. Graham red squirrel—a model system to demonstrate how disturbances can threaten the persistence of range-limited species. We document survival, space use, and displacement prior to and following fires and discuss implications for conservation. We suggest that management plans address future threats, including disturbance-related habitat loss.
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