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Richard G Coss - One of the best experts on this subject based on the ideXlab platform.
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california ground squirrels Spermophilus beecheyi
2016Co-Authors: Richard G Coss, James E BiardiAbstract:California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against their two predators, the northern Pacific rattlesnake (Crotalus viridis oreganus) and Pacific gopher snake (Pituophis melanoleucus catenifer). Two studies were used to examine individual variation in antisnake behavior as it might be affected by selection operating on arousability, fearfulness, and aggressiveness. In Study 1 the behavioral consistency of two litters of lab-reared juveniles was examined at two age periods during encounters with a caged gopher snake and domestic cat. Close-range investigation and tail flagging appeared to be governed by short-term motivational states that were not strongly correlated across age. Age correlations revealed that individual tendencies to throw substrate were relatively consistent for the snake and even more so for the cat. In Study 2, wild-caught adults were obtained from five sites where rattlesnakes and gopher snakes were abundant and from five sites where these snakes were rare or absent. Squirrels in a seminatural laboratory setting were given balanced presentations of a caged rattlesnake and gopher snake separated by 5 days. Snakes were recognized by all squirrels as potentially dangerous, irrespective of experience, age, and selective regime. Substrate throwing also was positively correlated for the two snakes in both groups of adults, indicating that level of aggressiveness is a consistent component of temperament not specific to species of snakes. Physiological arousal was not correlated strongly for the two snakes, but it was significantly lower in squirrels from sites where snakes were abundant. This suggests some specialization to reduce anxiety that possibly enhances tactical decision making.
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the effects of wind turbines on antipredator behavior in california ground squirrels Spermophilus beecheyi
Biological Conservation, 2006Co-Authors: Lawrence A Rabin, Richard G Coss, Donald H OwingsAbstract:Electricity-generating wind turbines are an attractive energy source because they are renewable and produce no emissions. However, they have at least two potentially damaging ecological effects. Their rotating blades are hazardous to raptors which occasionally fly into them. And wind turbines are very noisy when active, a feature that may interfere with the lives of animals beneath them. We studied California ground squirrels (Spermophilus beecheyi) in the Altamont Pass Wind Resource Area of Northern California. These squirrels emit vocalizations that alert others to the presence of a predator, and so may be forced to compensate for turbine noise by modifying antipredator behavior. We compared the antipredator behavior of squirrels at two sites, one close to and the other far from turbines, and under two conditions, during baseline and playback of conspecific alarm calls. We generated composite two variables using principle components analysis, one representing vigilance and one representing another cautionary antipredator tactic, for further statistical comparisons. Animals at the Turbine site exhibited elevated levels of vigilance and showed increased caution demonstrated in part, by returning to the area near their burrows during alarm calling. We conclude that this site difference is probably caused by the disparity in turbine noise, since predator abundance, group size, and vegetation type and density were similar for the two sites. Though population level impacts of these behavioral differences remain to be explored, our results indicate that behavioral impacts of turbines on wildlife should be considered during future turbine development.
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California Ground Squirrel (Spermophilus beecheyi) Defenses Against Rattlesnake Venom Digestive and Hemostatic Toxins
Journal of Chemical Ecology, 2006Co-Authors: James E Biardi, David C. Chien, Richard G CossAbstract:Previous studies have shown that some mammals are able to neutralize venom from snake predators. California ground squirrels ( Spermophilus beecheyi ) show variation among populations in their ability to bind venom and minimize damage from northern Pacific rattlesnakes ( Crotalus oreganus ), but the venom toxins targeted by resistance have not been investigated. Four California ground squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for their ability to neutralize digestive and hemostatic effects of venom from three rattlesnake species. In Douglas ground squirrels ( S. b. douglasii ), we found that animals from a location where snakes are common showed greater inhibition of venom metalloprotease and hemolytic activity than animals from a location where snakes are rare. Effects on general proteolysis were not different. Douglas ground squirrels also reduced the metalloprotease activity of venom from sympatric northern Pacific rattlesnakes ( C. o. oreganus ) more than the activity of venom from allopatric western diamondback rattlesnakes ( C. atrox ), but enhanced the fibrinolysis of sympatric venom almost 1.8 times above baseline levels. Two Beechey ground squirrel ( S. b. beecheyi ) populations had similar inhibition of venoms from northern and southern Pacific rattlesnakes ( C. o. helleri ), despite differences between the populations in the locally prevalent predator. However, the venom toxins inhibited by Beechey squirrels varied among venom from Pacific rattlesnake subspecies, and between these venoms and venom from allopatric western diamondback rattlesnakes. Blood plasma from Beechey squirrels showed highest inhibition of metalloprotease activity of northern Pacific rattlesnake venom, general proteolytic activity and hemolysis of southern Pacific rattlesnake venom, and hemolysis by allopatric western diamondback venom. These results reveal previously cryptic variation in venom activity against resistant prey that suggests reciprocal adaptation at the molecular level.
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age differences in arousal and vigilance in california ground squirrels Spermophilus beecheyi
Developmental Psychobiology, 2001Co-Authors: Mark T Hanson, Richard G CossAbstract:Newly emerged pup, juvenile, and adult California ground squirrels (Spermophilus beecheyi douglasii) were videorecorded at a seminatural field site in northern California. Video data revealed age differences in the budgeting of ground squirrel behavior, habitat use, and physiological arousal as indicated by morphometric analyses of tail piloerection. Adults and juveniles devoted their time to foraging in the open at feeding stations while displaying low to moderate levels of arousal, respectively. Pups remained vigilant on the fringe of covered habitats while displaying comparatively higher levels of arousal. Higher pup arousal may facilitate memory formation during early stages of development. © 2001 John Wiley & Sons, Inc. Dev Psychobiol 39: 199–206, 2001
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age differences in the response of california ground squirrels Spermophilus beecheyi to conspecific alarm calls
Ethology, 2001Co-Authors: Mark T Hanson, Richard G CossAbstract:Juvenile California ground squirrel responses to adult alarm calls and juvenile alarm calling may be modified during development to achieve adult form. Adult conspecific chatter and whistle alarm calls were played back to juvenile and adult ground squirrels at an agricultural field site. In response to chatter playbacks, adults spent more time visually orienting to the environment and less time out of view and in covered habitats than juveniles: the converse was true in response to whistle playbacks. To test the evocativeness of juvenile calling, a subset of adult subjects received juvenile chatter and whistle playbacks. Adults spent less time out of view to juvenile call types than to adult calls, and showed more similar responses to juvenile chatters and whistles than to adult chatters and whistles. Age differences in the ground squirrel's alarm call system may reflect adjustments to changing risks during development.
James E Biardi - One of the best experts on this subject based on the ideXlab platform.
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california ground squirrels Spermophilus beecheyi
2016Co-Authors: Richard G Coss, James E BiardiAbstract:California ground squirrels (Spermophilus beecheyi) have evolved behavioral defenses against their two predators, the northern Pacific rattlesnake (Crotalus viridis oreganus) and Pacific gopher snake (Pituophis melanoleucus catenifer). Two studies were used to examine individual variation in antisnake behavior as it might be affected by selection operating on arousability, fearfulness, and aggressiveness. In Study 1 the behavioral consistency of two litters of lab-reared juveniles was examined at two age periods during encounters with a caged gopher snake and domestic cat. Close-range investigation and tail flagging appeared to be governed by short-term motivational states that were not strongly correlated across age. Age correlations revealed that individual tendencies to throw substrate were relatively consistent for the snake and even more so for the cat. In Study 2, wild-caught adults were obtained from five sites where rattlesnakes and gopher snakes were abundant and from five sites where these snakes were rare or absent. Squirrels in a seminatural laboratory setting were given balanced presentations of a caged rattlesnake and gopher snake separated by 5 days. Snakes were recognized by all squirrels as potentially dangerous, irrespective of experience, age, and selective regime. Substrate throwing also was positively correlated for the two snakes in both groups of adults, indicating that level of aggressiveness is a consistent component of temperament not specific to species of snakes. Physiological arousal was not correlated strongly for the two snakes, but it was significantly lower in squirrels from sites where snakes were abundant. This suggests some specialization to reduce anxiety that possibly enhances tactical decision making.
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isolation and identification of a snake venom metalloproteinase inhibitor from california ground squirrel Spermophilus beecheyi blood sera
Toxicon, 2011Co-Authors: James E Biardi, J Marcinczyk, K P NambiarAbstract:California ground squirrels (Spermophilus beecheyi) show blood-based defenses to a variety of toxins in the venom of the Northern Pacific rattlesnake (Crotalus oreganus oreganus). In this study we demonstrate the presence of an effective snake venom metalloproteinase inhibitor (SVMPI) in S. beecheyi. The blood sera of California ground squirrels were effective at reducing the metalloproteinase activity of Northern Pacific (C. o. oreganus) and prairie rattlesnake (Crotalus viridis viridis) venoms by over 75%, significantly more than its ability to reduce the activity of western diamondback rattlesnake venom. We used anion exchange and affinity chromatography to isolate this protein from the blood sera of S. beecheyi. This SVMPI had a molecular mass of 108.3 kDa and a pI of 5.1. The IC(50) of this inhibitor against whole venom from C. o. oreganus was determined to be 3.14 × 10(-8) M. Subsequent LC MS/MS analysis of a CNBr/tryptic digest of the inhibitor yielded multiple internal peptide sequences. These sequences showed homology to three other known mammalian plasma proteins: inter-α trypsin inhibitor, and two hibernation-associated proteins, HP25 and HP27. The presence of SVMPI in S. beecheyi blood sera is consistent with the resistance of these animals to venom-induced hemorrhage and tissue damage, and consistent with the protective factors conferring venom resistance in other mammals. However, the variety of SVMPI identified to date from mammalian taxa suggests that different species have converged on neutralization of venom metalloproteinase activity as a key step in venom neutralization.
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California Ground Squirrel (Spermophilus beecheyi) Defenses Against Rattlesnake Venom Digestive and Hemostatic Toxins
Journal of Chemical Ecology, 2006Co-Authors: James E Biardi, David C. Chien, Richard G CossAbstract:Previous studies have shown that some mammals are able to neutralize venom from snake predators. California ground squirrels ( Spermophilus beecheyi ) show variation among populations in their ability to bind venom and minimize damage from northern Pacific rattlesnakes ( Crotalus oreganus ), but the venom toxins targeted by resistance have not been investigated. Four California ground squirrel populations, selected for differences in local density or type of rattlesnake predators, were assayed for their ability to neutralize digestive and hemostatic effects of venom from three rattlesnake species. In Douglas ground squirrels ( S. b. douglasii ), we found that animals from a location where snakes are common showed greater inhibition of venom metalloprotease and hemolytic activity than animals from a location where snakes are rare. Effects on general proteolysis were not different. Douglas ground squirrels also reduced the metalloprotease activity of venom from sympatric northern Pacific rattlesnakes ( C. o. oreganus ) more than the activity of venom from allopatric western diamondback rattlesnakes ( C. atrox ), but enhanced the fibrinolysis of sympatric venom almost 1.8 times above baseline levels. Two Beechey ground squirrel ( S. b. beecheyi ) populations had similar inhibition of venoms from northern and southern Pacific rattlesnakes ( C. o. helleri ), despite differences between the populations in the locally prevalent predator. However, the venom toxins inhibited by Beechey squirrels varied among venom from Pacific rattlesnake subspecies, and between these venoms and venom from allopatric western diamondback rattlesnakes. Blood plasma from Beechey squirrels showed highest inhibition of metalloprotease activity of northern Pacific rattlesnake venom, general proteolytic activity and hemolysis of southern Pacific rattlesnake venom, and hemolysis by allopatric western diamondback venom. These results reveal previously cryptic variation in venom activity against resistant prey that suggests reciprocal adaptation at the molecular level.
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california ground squirrel Spermophilus beecheyi blood sera inhibits crotalid venom proteolytic activity
Toxicon, 2000Co-Authors: James E Biardi, Richard G Coss, David Glenn SmithAbstract:Some California ground squirrels (Spermophilus beecheyi) show limited necrosis following envenomation by northern Pacific rattlesnakes (Crotalus viridis oreganus). This study demonstrates that S. beecheyi blood sera inhibits venom proteases. Sera from rattlesnake-abundant habitats inhibited C. v. oreganus venom more effectively than venom from two allopatric rattlesnake species, C. v. viridis and C. atrox, suggesting evolutionary specialization. The pattern of inhibition among squirrel populations corresponds best with history of rattlesnake predation, in contrast to current rattlesnake density.
Terrell P Salmon - One of the best experts on this subject based on the ideXlab platform.
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assessing the effectiveness of bait stations for controlling california ground squirrels Spermophilus beecheyi
Crop Protection, 2009Co-Authors: Desley A. Whisson, Terrell P SalmonAbstract:Abstract Bait stations are frequently used in wildlife management programs; however, social factors of the target population as well as the design and placement of bait stations may limit their effectiveness and in some cases result in individuals consuming excessive amounts of bait. We conducted field trials to evaluate the effectiveness of bait stations for delivering a first-generation anticoagulant (diphacinone – 0.005%) bait to California ground squirrels ( Spermophilus beecheyi ), and the potential non-target hazards associated with this technique. Using a non-toxic bait containing Keystone Oil Blue A as a biomarker, we determined that squirrels within 100 m of a bait station consumed bait. Males consumed more bait than females and were more frequently observed at bait stations. During a monitored baiting program, ground squirrels died between 14 and 42 days after bait station placement. Results of our trials suggest that territorial individuals may exclude others from the bait until they succumb to diphacinone. This may result in some squirrels consuming significantly more bait than necessary to obtain a lethal dose, and contribute to potentially higher secondary hazards in the field.
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comparison of 0 005 and 0 01 diphacinone and chlorophacinone baits for controlling california ground squirrels Spermophilus beecheyi
Wildlife Research, 2007Co-Authors: Terrell P Salmon, Are R Berentsen, Desley A. Whisson, Paul W GorenzelAbstract:Abstract.Diphacinone and chlorophacinone, first-generation anticoagulant rodenticides, are frequently used for control of California ground squirrels (Spermophilus beecheyi) in agricultural and rangeland areas in California, USA. Owing to growing concerns over the risks to non-target species associated with the use of these rodenticides, the USA Environmental Protection Agency (EPA) proposed that the concentration of baits for above-ground use should be reduced from 0.01% to 0.005% active ingredient. We conducted field trials to compare the efficacy of 0.005% and 0.01% chlorophacinone and diphacinone baits in broadcast and spot applications for control of California ground squirrels on rangeland. We found no significant difference in efficacy owing to bait type, concentration or application method. Repeat testing is needed in other habitat types (e.g. crop areas) where alternative foods might reduce the effectiveness of a 0.005% bait application.
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rodenticide grain bait ingredient acceptance by norway rats rattus norvegicus california ground squirrels Spermophilus beecheyi and pocket gophers thomomys bottae
Pest Management Science, 2006Co-Authors: Terrell P Salmon, Ned A DochtermannAbstract:Vertebrate pest control in California is often accomplished through the use of rodenticide grain baits. These grain baits are composed of steam-rolled oats (SRO), a toxicant, an indicator dye and an oil combination. A series of tests were performed to determine the effects of various dye and oil formulations on acceptance of grain bait by Norway rats [Rattus norvegicus (Berk)], California ground squirrels [Spermophilus beecheyi (Richardson)] and pocket gophers (Thomomys bottae Eyd & Gerv). Seven different dyes, four oil formulations and clean (untreated) oats were tested for acceptance. The addition of the selected oils and dyes to grain resulted in no significant differences in consumption. This indicates that there is a wide variety of dyes that could be used in the formulation of rodenticides. These alternatives could aid in proper pesticide use, the deterrence of bait consumption by birds and possibly in ingredient adhesion to the finished bait.
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grower evaluation of california ground squirrel Spermophilus beecheyi control using anticoagulant baits
Proceedings of the Vertebrate Pest Conference, 2006Co-Authors: Victor J Kowalski, Rachel Long, Jim Sullins, Sergio Garcia, Terrell P SalmonAbstract:Author(s): Kowalski, Victor J.; Long, Rachel; Sullins, Jim; Garcia, Sergio; Salmon, Terrell P. | Abstract: California ground squirrels continue to present a significant problem for many facets of California agriculture. The use of diphacinone- and chlorophacinone-treated baits remains the most frequent control method for ground squirrels in agricultural settings. Research suggests no difference in efficacy between the two bait types or between broadcast and spot baiting strategies or bait stations. However, these studies were limited in scope and were conducted exclusively on rangeland sites where there is limited availability of alternate food sources. Studies also suggest that a reduced baiting strategy may be as effective as current label recommendations, but this has received only limited attention in field research. We utilized a new approach in conducting field evaluations of anticoagulant baiting efficacy in different agricultural settings and locations throughout the state. We solicited agricultural producers as cooperators to participate in a field-based evaluation to determine if the reduced baiting strategies are effective under specific agricultural operating conditions. Cooperators were trained in a simple research design and monitored to ensure consistent data collection. The training program included a comprehensive manual on squirrel biology, behavior, and control, as well as information on toxicants and legal measures regarding endangered species. An informal survey was sent to cooperators at the end of the project to evaluate their opinions on the efficacy of control methods. We found no difference in efficacy between baiting methods or strategies. Differences in efficacy were found between chlorophacinone and diphacinone and efficacy was lower in nut orchards than in other settings. Despite no difference in efficacy between baiting methods, more cooperators indicated they would use bait stations than other methods in future ground squirrel control operations.
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effect of the timing of applications and amount of 0 01 diphacinone consumed on mortality of california ground squirrels Spermophilus beecheyi
Crop Protection, 2002Co-Authors: Desley A. Whisson, Terrell P SalmonAbstract:Abstract Diphacinone, a first-generation anticoagulant rodenticide is used extensively for control of California ground squirrels (Spermophilus beecheyi). The potential for secondary poisoning hazards, has necessitated development of baiting strategies that minimize the amount of bait applied, while still providing a high level of control. Laboratory studies conducted to determine the effect of the amount of bait, number, and timing of 0.01% diphacinone bait applications on mortality rate of California ground squirrels suggest that only 2 applications with 3–5 d between applications are necessary to achieve control. This is contrary to previous beliefs that there must be no more than 48 h between feedings. Reducing the amount of bait per application by 71% had no significant effect on mortality rate.
Donald H Owings - One of the best experts on this subject based on the ideXlab platform.
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alarm calls of california ground squirrels Spermophilus beecheyi
Ethology, 2010Co-Authors: Donald H Owings, Ross A VirginiaAbstract:California ground squirrel alarm vocalizations were recorded in field and laboratory, and sonagraphically analysed. The contexts of both naturally occurring and experimentally elicited calls were noted in the field. The components of this graded system are chatters, chats and whistles. Chatters and chats are often elicited by terrestrial predators, whistles commonly by low flying raptors. Whistles are more commonly associated with cryptic behavior and flight than chatter-chats, but both call types usually elicit bipedal alert postures. These calls grade along a number of dimensions which may signal redundantly the level of excitation of the caller. We propose that the chatter-chat calls of highly aroused squirrels are composed of more and longer notes, occur at a higher rate, are less noisy and contain more frequency modulation. Whistles, however, are single-note calls that contain no frequency modulation, even though they are emitted by highly aroused squirrels and are long and noise free. Preliminary data suggest that: 1) chats are easier for a human ♀ to localize than whistles; 2) elevation of the head, by adopting bipedal postures and mounting promontories, enhances the audibility of alarms.
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probing assessment and management during interactions between ground squirrels rodentia sciuridae and rattlesnakes squamata viperidae 2 cues afforded by rattlesnake rattling
Ethology, 2010Co-Authors: Donald H Owings, Matthew P RoweAbstract:The predator-prey relationship between California ground squirrels (Spermophilus beecheyi) and northern Pacific rattlesnakes (Crotalus riridis oreganus) is a useful system in which to explore risk assessment and management. Rattlesnakes are major predators of ground-squirrel pups, but pose only a sublethal threat to adult squirrels. Adults approach, harass, and even attack rattlesnakes when confronted with them. A rattlesnake's response to such harassment can include rattling and striking. Not all rattlesnakes pose the same risk to an adult squirrel. Larger, warmer rattlesnakes strike in ways that may be more effective at overwhelming the defensive leaps of squirrels, and larger snakes can inject more venom if they are successful in landing a bite. It would therefore benefit squirrels to assess and respond appropriately to rattlesnakes of different body size and temperature. We looked for cues in rattling upon which such assessments might be based. We recorded and digitally analyzed the rattling sounds of snakes of different sizes, each tested at four different body temperatures — 10, 18, 27, and 35°C. Results indicate that warmer snakes rattle with faster click rates, higher amplitudes, and shorter latencies. Similarly, larger snakes produce rattling sounds of higher amplitude and lower dominant frequencies. Thus, rattling provides reliable cues about rattlesnake dangerousness. Nevertheless, this highly ‘informative’ characteristic of rattling has its origins in physical and physiological constraints, not in specialization for communication. Ground squirrels appear to probe for the information extractable from rattling, for example by pushing loose substrate at the snake and thus inducing it to rattle. Future reports will discuss the degree to which ground squirrels actually exploit these cues.
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the effects of wind turbines on antipredator behavior in california ground squirrels Spermophilus beecheyi
Biological Conservation, 2006Co-Authors: Lawrence A Rabin, Richard G Coss, Donald H OwingsAbstract:Electricity-generating wind turbines are an attractive energy source because they are renewable and produce no emissions. However, they have at least two potentially damaging ecological effects. Their rotating blades are hazardous to raptors which occasionally fly into them. And wind turbines are very noisy when active, a feature that may interfere with the lives of animals beneath them. We studied California ground squirrels (Spermophilus beecheyi) in the Altamont Pass Wind Resource Area of Northern California. These squirrels emit vocalizations that alert others to the presence of a predator, and so may be forced to compensate for turbine noise by modifying antipredator behavior. We compared the antipredator behavior of squirrels at two sites, one close to and the other far from turbines, and under two conditions, during baseline and playback of conspecific alarm calls. We generated composite two variables using principle components analysis, one representing vigilance and one representing another cautionary antipredator tactic, for further statistical comparisons. Animals at the Turbine site exhibited elevated levels of vigilance and showed increased caution demonstrated in part, by returning to the area near their burrows during alarm calling. We conclude that this site difference is probably caused by the disparity in turbine noise, since predator abundance, group size, and vegetation type and density were similar for the two sites. Though population level impacts of these behavioral differences remain to be explored, our results indicate that behavioral impacts of turbines on wildlife should be considered during future turbine development.
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the rattling sound of rattlesnakes crotalus viridis as a communicative resource for ground squirrels Spermophilus beecheyi and burrowing owls athene cunicularia
Journal of Comparative Psychology, 2002Co-Authors: Donald H Owings, Matthew P Rowe, Aaron S RundusAbstract:Animal communication involves very dynamic processes that can generate new uses and functions for established communicative activities. In this article, the authors describe how an aposematic signal, the rattling sound of rattlesnakes (Crotalus viridis), has been exploited by 2 ecological associates of rattlesnakes: (a) California ground squirrels ( Spermophilus beecheyi) use incidental acoustic cues in rattling sounds to assess the danger posed by the rattling snake, and (b) burrowing owls ( Athene cunicularia) defend themselves against mammalian predators by mimicking the sound of rattling. The remarkable similarity between the burrowing owl’s defensive hiss and the rattlesnake’s rattling reflects both exaptation and adaptation. Such exploitation of the rattling sound has favored alternations in both the structure and the deployment of rattling by rattlesnakes.
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do california ground squirrels Spermophilus beecheyi use ritualized syntactic cephalocaudal grooming as an agonistic signal
Journal of Comparative Psychology, 2000Co-Authors: Stanley N Bursten, Kent C Berridge, Donald H OwingsAbstract:Animal communication theory holds that many signals have evolved from nonsignal precursors. This field and laboratory study of California ground squirrels (Spermophilus beecheyi) provides evidence for the coexistence of such a precursor with its derived display. The precursor is an ancient, endogenously sequenced (syntactic) pattern of cephalocaudal grooming movements (CCGs) shared by all rodent suborders. The following evidence supports the hypothesis that a supernormal version of this pattern has been selected for signal function. Syntactic CCGs in the field (a) were more rigidly stereotyped than ordinary syntactic CCGs in the laboratory; (b) differed from laboratory syntactic CCGs in other ways that enhanced their conspicuousness, in part through exaggeration of the syntactic cephalocaudal pattern; (c) were associated with scent marking and social staring; and (d) were associated with intrasexual agonistic encounters that did not escalate to fighting.
K P Nambiar - One of the best experts on this subject based on the ideXlab platform.
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isolation and identification of a snake venom metalloproteinase inhibitor from california ground squirrel Spermophilus beecheyi blood sera
Toxicon, 2011Co-Authors: James E Biardi, J Marcinczyk, K P NambiarAbstract:California ground squirrels (Spermophilus beecheyi) show blood-based defenses to a variety of toxins in the venom of the Northern Pacific rattlesnake (Crotalus oreganus oreganus). In this study we demonstrate the presence of an effective snake venom metalloproteinase inhibitor (SVMPI) in S. beecheyi. The blood sera of California ground squirrels were effective at reducing the metalloproteinase activity of Northern Pacific (C. o. oreganus) and prairie rattlesnake (Crotalus viridis viridis) venoms by over 75%, significantly more than its ability to reduce the activity of western diamondback rattlesnake venom. We used anion exchange and affinity chromatography to isolate this protein from the blood sera of S. beecheyi. This SVMPI had a molecular mass of 108.3 kDa and a pI of 5.1. The IC(50) of this inhibitor against whole venom from C. o. oreganus was determined to be 3.14 × 10(-8) M. Subsequent LC MS/MS analysis of a CNBr/tryptic digest of the inhibitor yielded multiple internal peptide sequences. These sequences showed homology to three other known mammalian plasma proteins: inter-α trypsin inhibitor, and two hibernation-associated proteins, HP25 and HP27. The presence of SVMPI in S. beecheyi blood sera is consistent with the resistance of these animals to venom-induced hemorrhage and tissue damage, and consistent with the protective factors conferring venom resistance in other mammals. However, the variety of SVMPI identified to date from mammalian taxa suggests that different species have converged on neutralization of venom metalloproteinase activity as a key step in venom neutralization.