We validated a radioimmunoassay-based method quantifying fecal glucocorticoid metabolites （FGMs） from captive male and female Richardson＇s ground squirrels Urocitellus richardsonii. Blood samples were drawn to expl...We validated a radioimmunoassay-based method quantifying fecal glucocorticoid metabolites （FGMs） from captive male and female Richardson＇s ground squirrels Urocitellus richardsonii. Blood samples were drawn to explore the correlation between plasma cortisol and FGM concentrations. We also injected groups of squirrels with normal saline （CTL; control）, adre- nocorticotropic hormone （ACTH; stimulating adrenal activity）, or dexamethasone （DEX; suppressing adrenal activity）. Potential correlations between stress and behaviour were explored through quantification of fecal pellet production and the intervention necessary to elicit defecation, as well as the behaviour of subjects in the context of handling. Changes in plasma cortisol concen- tration between capture （baseline）, and following handling （stress-induced） were also quantified for free-living squirrels. While glucocorticoid concentrations recovered from feces during our captive-animal study were not well correlated with plasma eortisol concentrations, and uncorrelated with defecation or behaviour, FGM concentrations did reflect the activation of the hypothalamic- pituitary-adrenal （HPA） axis. FGM concentrations increased significantly during initial captivity, but declined to baseline level as individuals acclimated to the novel environment. Injection of subjects with ACTH increased FGMs above baseline, confirming activation of the HPA axis. Plasma cortisol concentrations increased significantly with induced stress, indicating that capture and handling activated the glucocorticoid stress response even among previously handled, free-living subjects. Our findings validate a non-invasive tool that will afford new insight into the physiological processes underlying social, reproductive and antipredator behaviour of Richardson＇s ground squirrels [Current Zoology 60 （5）： 591-601, 2014 ].展开更多
Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to ...Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is un- known how ttrbanization has affected these behaviors. Multimodal commtmication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be pre- sented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Partan et al. （2009） by providing data on sig- naling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifics are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats [Current Zoology 56 （3）： 313-326, 2010].展开更多
Alarm calls of the European Spermophilus citellus （EGS）, Taurus S. taurensis （TGS） and Anatolian S. xanthoprymnus （AGS） ground squirrels share the same basic structure. They are tonal sounds consisting primarily...Alarm calls of the European Spermophilus citellus （EGS）, Taurus S. taurensis （TGS） and Anatolian S. xanthoprymnus （AGS） ground squirrels share the same basic structure. They are tonal sounds consisting primarily of two different elements. The first element, often produced without the second element, has limited frequency modulation, while the second element is more frequency modulated. The present study examined whether this frequency-modulated element enhances the individual distinc- tiveness of calls, allowing calls to be ascribed with greater confidence to individual callers of the three species. Cross-validated discriminant function analysis （DFA） based on five acoustic parameters of the first element successfully classified calls to correct individuals （EGS： 90%, TGS： 98%, AGS： 96%）. Cross-validated DFA based on five acoustic parameters of the second element was also successful in classifications （EGS： 88%, TGS： 86%, AGS： 96%）, though discrimination of callers based on parameters of the second versus first element was the same for the AGS, lower for the EGS and significantly lower for the TGS. Cross-validated DFA based on five acoustic parameters of two-element calls also successfully classified calls to correct individu- als （EGS： 93%, TGS： 98%, AGS： 97%）, though did not improve the extent to which calls could be classified to individuals be- yond that based on the ftrst element alone. Thus, the second element does not enhance the individual distinctiveness of calls, but may convey other information such as the location of the caller [Current Zoology 58 （5）： 749-757, 2012].展开更多
Alarm calls are emitted by Richardson＇s ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predato...Alarm calls are emitted by Richardson＇s ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predator detection and evasion, but in doing so, lose time from foraging. That loss can be minimized if alarm call recipients discriminate among signalers, and weight their response accordingly. For juvenile ground squirrels, we predicted that the trade-off between foraging and vigilance could be optimized via selective response to alarm calls emitted by their own dam, and/or neighboring colony members over calls broad- cast by less familiar conspecifics. Alarm calls of adult female Richardson＇s ground squirrels were elicited in the field using a predator model and recorded on digital audio tape. Free-living focal juveniles were subjected to playbacks of a call of their mother, and on a separate occasion a call from either another adult female from their own colony, or an adult female from another colony. Neither immediate postural responses and escape behavior, nor the duration of vigilance manifested by juveniles differed with exposure to alarm calls of the three adult female signaler types. Thus, juveniles did not respond preferentially to alarm calls emitted by their mothers or colony members, likely reflecting the high cost of ignoring alarm signals where receivers have had limited opportunity to establish past signaler reliability [Current Zoology 58 （5）： 773-780, 2012].展开更多
In grassland ecosystems,burrowing mammals create disturbances,providing habitat for animal species and increasing plant community diversity.We investigated whether seedling assemblages on Richardson's ground squir...In grassland ecosystems,burrowing mammals create disturbances,providing habitat for animal species and increasing plant community diversity.We investigated whether seedling assemblages on Richardson's ground squirrel Urocitellus richardsonii mounds result from seed rearrangement or environmental changes that favor germination of certain species over others.To test whether ground squirrels rearrange the seed bank by burrowing,we compared seed compositions among mounds,burrows,and undisturbed soil.To test whether ground squirrels change environmental conditions,we compared soil nitrate and bare ground cover on and off mounds.We also compared seedlings that germinated on mounds with seedlings that germinated on artificial disturbances from which we removed aboveground vegetation.Soil nitrate and bare ground cover were significantly higher on mounds than artificial disturbances.While seed richness and abundance did not differ among mounds,burrows,and undisturbed soil,seedling richness was reduced on mounds relative to artificial disturbances.Burrowing disturbance favors seedlings that can capitalize on bare ground availability but are less able to immobilize nitrate,as opposed to perennial species that immobilize more nitrate but take longer to establish.Our results suggest that Richardson's ground squirrels act as ecosystem engineers,although future research following succession on ground squirrel mounds is necessary to understand how they influence plant communities past the seedling stage.展开更多
In this study, we examined the use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in three coniferous and mixed forests in Gangwon Province, South Korea. Six hundred and twelve boxes with diff...In this study, we examined the use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in three coniferous and mixed forests in Gangwon Province, South Korea. Six hundred and twelve boxes with different sized entry holes (ranging from 3 to 7 cm in diameter) were placed in the forests between 2004 and 2009. Pteromys volans used nine boxes in the coniferous forests and two boxes in the mixed forests. The squirrels only used boxes with entrance holes measuring 3.5, 4, and 5 cm in diameter, showing a strong and moderate preference for boxes with 5 and 4-cm holes, respectively, and a strong avoidance for boxes with 3- and 7-cm holes. Therefore, we suggest placing artificial nest boxes with entrance holes 5 cm in diameter to encourage breeding activity. Most nests made in the artificial boxes were composed of fibrous materials from woody vines. We recommend placing artificial nest boxes with holes of 5-cm diameter in coniferous forests, which support dense populations of P. volans, to survey whether this approach would positively affect the breeding habits and population maintenance of this species.展开更多
Oaks(Quercus spp.)provide an important food source for many wildlife species throughout the fall and winter.Most research evaluating oak masting patterns and the subsequent behavioral responses of wildlife focuses on ...Oaks(Quercus spp.)provide an important food source for many wildlife species throughout the fall and winter.Most research evaluating oak masting patterns and the subsequent behavioral responses of wildlife focuses on the annual temporal scale.However,patterns in masting at the seasonal temporal scale may be important for wildlife behavior.We designed a study quantifying seasonal oak masting patterns of 3 oak species(water oak,Q.nigra;laurel oak,Q.laurifolia;and swamp chestnut oak,Q.michauxii)and linking those patterns to visitation and feeding behavior of 3 primary consumers(white-tailed deer,Odocoileus virginianus;gray squirrel,Sciurus carolinensis;and raccoon,Procyon lotor).We used seed traps to monitor the seasonal masting pattern of 205 trees in the fall of 2021 and 2022 and used camera traps concurrently to monitor wildlife behavior associated with a subset of 30 trees.Seasonal masting patterns differed between oak species both within a season and across years,and the timing of mast varied within oak species across years.White-tailed deer tended to visit swamp chestnut oak as the number of acorns increased and consumed their acorns.Gray squirrels and raccoons tended to visit laurel oak and consume water oak acorns with gray squirrels being more likely to consume as the number of acorns increased.Our results indicate that evaluating acorn production at multiple temporal scales may be necessary to fully understand oak masting relationships with wildlife.Furthermore,differences in wildlife behavior based on oak species may have important implications for oak regeneration.展开更多
Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adi...Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adipose tissue（WAT） during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six mi RNAs including let-7a, let-7b, mi R-107, mi R-150, mi R-222 and mi R-31 was significantly downregulated in WAT（P 〈 0.05）, which was 16%–54% of euthermic non-torpid control squirrels,whereas expression of three mi RNAs including mi R-143, mi R-200 a and mi R-519 d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more mi RNAs was downregulated in BAT during torpor. We detected reduced expression of 6 mi RNAs including mi R-103 a, mi R-107, mi R-125 b, mi R-21, mi R-221 and mi R-31（48%–70% of control）, while only expression of mi R-138 was significantly upregulated（2.91 ± 0.8-fold of the control, P 〈 0.05）. Interestingly,mi RNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas mi RNAs with altered expression in BAT during torpor were linked to mitochondrial b-oxidation. mi RPath target prediction analysis showed that mi RNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase（MAPK） signaling, while the mi RNAs upregulated in WAT were linked to transforming growth factor b（TGFb） signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-mi RNAs for the mi RNAs used in this study, suggesting no structure-influenced changes in pre-mi RNA processing efficiency in the squirrel. As well, the expression of mi RNA processingenzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of mi RNA expression in adipose tissues may be linked to distinct biological roles in WAT and BAT during hibernation and may involve the regulation of signaling cascades.展开更多
The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities.Hematoxylin-eosin staining showed ...The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities.Hematoxylin-eosin staining showed all types of elongated spermatids and spermatogenic cells existed in the testis in April,while the primary spermatocytes and spermatogonia were most advanced stages of germ cells in June.In addition,the primary spermatocytes,secondary spermatocytes,and spermatogonia were most advanced stages of germ cells in September.The highest circulating leptin concentration was consistent with the maximum body weight results from accumulation of adipose tissue in September.The mRNA expression level of leptin receptor(Ob-R)and STAT3 was lowest in June,raised in September,and remained increased in April.Ob-R and STAT3 were stronger staining in the Leydig cells in July.Moreover,the concentrations of testosterone(T)showed the maximum values in April,the minimum values in June,and significant increases in September.Furthermore,it is worth noting that the levels of T increased with the mRNA levels of Ob-R,STAT3,StAR,and testicular steroidogenic enzymes(3β-HSD,P450c17,and P450scc).Moreover,RNA-seq analyses of testis during the different periods showed that a total of 4209 genes were differ-entially expressed genes(DEGs);further analysis revealed that DEGs related with the Jak/STAT pathways and reproduction were altered.Taken together,the results suggested that the leptin regulated testicular function through the Jak/STAT pathways and testicular steroidogenic factor expressions.展开更多
Grey squirrels(Sciurus carolinensis)are an invasive species in Britain and Italy.They have replaced native red squirrels(Sciurus vulgaris)throughout most of Britain,and cause damage to trees.Currently,lethal control i...Grey squirrels(Sciurus carolinensis)are an invasive species in Britain and Italy.They have replaced native red squirrels(Sciurus vulgaris)throughout most of Britain,and cause damage to trees.Currently,lethal control is used to manage grey squirrel populations in Britain,but nonlethal methods might be more acceptable to the public.One such method is contraception with 20,25-diazacholesterol dihydrochloride(DiazaCon^(TM)).DiazaCon^(TM) inhibits the conversion of desmosterol to cholesterol,resulting in increasing desmosterol concentrations and decreasing cholesterol concentrations.Because cholesterol is needed for the synthesis of steroid reproductive hormones,such as progesterone and testosterone,inhibition of cholesterol synthesis indirectly inhibits reproduction.Desmosterol is used as a marker of efficacy in laboratory studies with species that do not reproduce readily in captivity.Grey squirrels were gavaged with a DiazaCon^(TM) solution for 2 days,and then fed DiazaCon^(TM)-coated peanuts for an additional 8 days at target doses of 50 and 100 mg DiazaCon^(TM) per kg body weight.There was a significant difference in cholesterol concentrations in the treatment groups compared to the control group.Cholesterol was reduced by≥40%for 2 months in both treatment groups.There were no differences among groups with respect to blood chemistry and hematology parameters,and mean values are reported.The mean overall dose of DiazaCon^(TM) received was 29.0±1.6 and 55.3±4.3 mg/kg in the low(50 mg/kg)and high dose(100 mg/kg)groups,respectively.DiazaCon^(TM) might provide an effective,acceptable alternative to lethal control.展开更多
Juvenile survival is a key life-history influence on population dynamics and adaptive evolution.We analyzed the effects of individual chara-cteristics,early environment,and maternal investment on juvenile survival in ...Juvenile survival is a key life-history influence on population dynamics and adaptive evolution.We analyzed the effects of individual chara-cteristics,early environment,and maternal investment on juvenile survival in a large solitary hibernating rodent-yellow ground squirrel Spermophilus fulvus using Cox mixed-effects models.Only 48%of weaned pups survived to dispersal and 17%survived to hibernation.Early life expectancy was primarily determined by individual characteristics and,to a lesser extent,by the early environment.The strongest and pos-itive predictor of juvenile survival was body mass which crucially affected mortality immediately after weaning.Males suffered higher mortality than females after the onset of dispersal;however,the overall difference between sexes was partly masked by high rates of mortality in the first days after emergence in both sexes.Later emerged juveniles had lower life expectancy than the earliest pups.The overall effect of local juvenile density was positive.Prolonged lactation did not enhance juvenile survival:Pups nursed longer survived shorter than the young nursed for a shorter period.Our findings support the hypothesis that females of S.fulvus cannot effectively regulate maternal expenditures to mitigate the effects of unfavorable conditions on their offspring.The strategy to deal with seasonal time constraints on life history in female S.fulvus suggests an early termination of maternal care at the cost of juvenile quality and survival.This female reproductive strategy corresponds to a"fast-solitary"life of folivorous desert-dwelling S.fulvus and other solitary ground squirrels with prolonged hibernation.展开更多
The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an...The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.展开更多
In the manufacturing industry,reasonable scheduling can greatly improve production efficiency,while excessive resource consumption highlights the growing significance of energy conservation in production.This paper st...In the manufacturing industry,reasonable scheduling can greatly improve production efficiency,while excessive resource consumption highlights the growing significance of energy conservation in production.This paper studies the problem of energy-efficient distributed heterogeneous permutation flowshop problem with variable processing speed(DHPFSP-VPS),considering both the minimum makespan and total energy consumption(TEC)as objectives.A discrete multi-objective squirrel search algorithm(DMSSA)is proposed to solve the DHPFSPVPS.DMSSA makes four improvements based on the squirrel search algorithm.Firstly,in terms of the population initialization strategy,four hybrid initialization methods targeting different objectives are proposed to enhance the quality of initial solutions.Secondly,enhancements are made to the population hierarchy system and position updating methods of the squirrel search algorithm,making it more suitable for discrete scheduling problems.Additionally,regarding the search strategy,six local searches are designed based on problem characteristics to enhance search capability.Moreover,a dynamic predator strategy based on Q-learning is devised to effectively balance DMSSA’s capability for global exploration and local exploitation.Finally,two speed control energy-efficient strategies are designed to reduce TEC.Extensive comparative experiments are conducted in this paper to validate the effectiveness of the proposed strategies.The results of comparing DMSSA with other algorithms demonstrate its superior performance and its potential for efficient solving of the DHPFSP-VPS problem.展开更多
In polymorphic mammalian species that display multiple color forms, those with dark, or melanic pelage would be prone to overheating, especially if they live in warm climates, because their fur absorbs solar energy at...In polymorphic mammalian species that display multiple color forms, those with dark, or melanic pelage would be prone to overheating, especially if they live in warm climates, because their fur absorbs solar energy at a higher rate. However, experimental studies indicate that certain physical properties of fur of dark individuals appear to prevent, or minimize heat stress, although it is not clear what properties do so. Here, we tested the possibility that black-furred individuals simply have shorter or thinner hair fibers, which would create a lighter （in terms of weight） coat or one that allows greater air flow for evaporative coo- ling. We examined museum specimens of eastern fox squirrels Sciurus niger, a species native to the United States and one that displays brown, grey or all-black pelage color, and used image analysis procedures to quantify hairs from the dorsal surface and tail. From examination of 43 specimens （19 brown, 9 black and 15 grey）, and 1,720 hairs, we found no significant difference in hair lengths across color morphs, but significant differences in hair fiber widths. Black squirrels had thinner body hairs than other forms （7% thinner）, but thicker tail hairs （9% thicker） than the others. Given that the dorsal surface would be directly exposed to solar radiation, we interpret this to be an adaptation to prevent heat stress during the day. The thicker tail hairs may be an adapta- tion for nighttime thermoregulation, since squirrels sleep with their tails wrapped around their bodies. These results add to a growing literature body of the functional significance of mammalian pelage [Current Zoology 57 （6）： 731-736, 2011].展开更多
Hole-nesting tits belonging to the family Paridae produce a hissing display that resembles the exhalatory hiss of a snake.When a predatory animal enters the nest hole of a tit,tits often hiss vigorously,while lunging ...Hole-nesting tits belonging to the family Paridae produce a hissing display that resembles the exhalatory hiss of a snake.When a predatory animal enters the nest hole of a tit,tits often hiss vigorously,while lunging their head forward and shaking their wings and tail,until the intruder retreats.We assessed the acoustic similarity between such hiss calls from 6 species of tits,snake hisses,and tit syllables used in alarm vocalizations,as well as white noise as a control.Tit hiss calls showed a high degree of similarity with snake hisses from 3 different snake families.Tit hisses had lower similarity to syllable alarm calls,suggesting convergence of tit hisses in their spectral structure.Hiss calls would only be effective in protecting nest boxes if nest predators responded to these calls.In order to test this hypothesis,we trained individual Swinhoe’s striped squirrels,Tamiops swinhoei hainanus,a common predator of egg and nestling tits,to feed at feeders in proximity to nest boxes.We compared the aversive response of squirrels to tit’s hiss calls and white noise,presented in random order.Squirrels showed a higher degree of avoidance of feeders when hiss calls were played back than when white noise was presented.In conclusion,our study suggests that hole-nesting birds have evolved convergent snake-like hiss calls,and that predators avoid to prey on the contents of nest boxes from which snake-like hisses emerge.展开更多
The Himalayan marmot Marmota himalayana is widely distributed across the Qinghai-Tibetan Plateau and lives in social groups,yet the mating system of this highly social marmot species is unknown.In this study,the genet...The Himalayan marmot Marmota himalayana is widely distributed across the Qinghai-Tibetan Plateau and lives in social groups,yet the mating system of this highly social marmot species is unknown.In this study,the genetic mating system of Himalayan marmots was inves-tigated using microsatellite markers to determine which mating strategies individuals employ.Results revealed that both monogamous and polygamous mating relationships occur in our study population,indicating that the genetic mating system of this marmot species is promiscuity.This study presents the first genetic evidence on the mating system for Himalayan marmots,yet indicates that further studies employing both a genetic and behavioral framework are needed to better understand the social structure and reproductive biology of this marmotspecies.展开更多
文摘We validated a radioimmunoassay-based method quantifying fecal glucocorticoid metabolites （FGMs） from captive male and female Richardson＇s ground squirrels Urocitellus richardsonii. Blood samples were drawn to explore the correlation between plasma cortisol and FGM concentrations. We also injected groups of squirrels with normal saline （CTL; control）, adre- nocorticotropic hormone （ACTH; stimulating adrenal activity）, or dexamethasone （DEX; suppressing adrenal activity）. Potential correlations between stress and behaviour were explored through quantification of fecal pellet production and the intervention necessary to elicit defecation, as well as the behaviour of subjects in the context of handling. Changes in plasma cortisol concen- tration between capture （baseline）, and following handling （stress-induced） were also quantified for free-living squirrels. While glucocorticoid concentrations recovered from feces during our captive-animal study were not well correlated with plasma eortisol concentrations, and uncorrelated with defecation or behaviour, FGM concentrations did reflect the activation of the hypothalamic- pituitary-adrenal （HPA） axis. FGM concentrations increased significantly during initial captivity, but declined to baseline level as individuals acclimated to the novel environment. Injection of subjects with ACTH increased FGMs above baseline, confirming activation of the HPA axis. Plasma cortisol concentrations increased significantly with induced stress, indicating that capture and handling activated the glucocorticoid stress response even among previously handled, free-living subjects. Our findings validate a non-invasive tool that will afford new insight into the physiological processes underlying social, reproductive and antipredator behaviour of Richardson＇s ground squirrels [Current Zoology 60 （5）： 591-601, 2014 ].
文摘Urbanization of animal habitats has the potential to affect the natural communication systems of any species able to survive in the changed environment. Urban animals such as squirrels use multiple signal channels to communicate, but it is un- known how ttrbanization has affected these behaviors. Multimodal commtmication, involving more than one sensory modality, can be studied by use of biomimetic mechanical animal models that are designed to simulate the multimodal signals and be pre- sented to animal subjects in the field. In this way the responses to the various signal components can be compared and contrasted to determine whether the multimodal signal is made up of redundant or nonredundant components. In this study, we presented wild gray squirrels in relatively urban and relatively rural habitats in Western Massachusetts with a biomimetic squirrel model that produced tail flags and alarm barks in a variety of combinations. We found that the squirrels responded to each unimodal component on its own, the bark and tail flag, but they responded most to the complete multimodal signal, containing both the acoustic and the moving visual components, providing evidence that in this context the signal components are redundant and that their combination elicits multimodal enhancement. We expanded on the results of Partan et al. （2009） by providing data on sig- naling behavior in the presence and absence of conspecifics, suggesting that alarm signaling is more likely if conspecifics are present. We found that the squirrels were more active in the urban habitats and that they responded more to tail flagging in the urban habitats as compared to the rural ones, suggesting the interesting possibility of a multimodal shift from reliance on audio to visual signals in noisier more crowded urban habitats [Current Zoology 56 （3）： 313-326, 2010].
文摘Alarm calls of the European Spermophilus citellus （EGS）, Taurus S. taurensis （TGS） and Anatolian S. xanthoprymnus （AGS） ground squirrels share the same basic structure. They are tonal sounds consisting primarily of two different elements. The first element, often produced without the second element, has limited frequency modulation, while the second element is more frequency modulated. The present study examined whether this frequency-modulated element enhances the individual distinc- tiveness of calls, allowing calls to be ascribed with greater confidence to individual callers of the three species. Cross-validated discriminant function analysis （DFA） based on five acoustic parameters of the first element successfully classified calls to correct individuals （EGS： 90%, TGS： 98%, AGS： 96%）. Cross-validated DFA based on five acoustic parameters of the second element was also successful in classifications （EGS： 88%, TGS： 86%, AGS： 96%）, though discrimination of callers based on parameters of the second versus first element was the same for the AGS, lower for the EGS and significantly lower for the TGS. Cross-validated DFA based on five acoustic parameters of two-element calls also successfully classified calls to correct individu- als （EGS： 93%, TGS： 98%, AGS： 97%）, though did not improve the extent to which calls could be classified to individuals be- yond that based on the ftrst element alone. Thus, the second element does not enhance the individual distinctiveness of calls, but may convey other information such as the location of the caller [Current Zoology 58 （5）： 749-757, 2012].
文摘Alarm calls are emitted by Richardson＇s ground squirrels Urocitellus richardsonii in response to avian and terrestrial predators. Conspecifics detecting these calls respond with increased vigilance, promoting predator detection and evasion, but in doing so, lose time from foraging. That loss can be minimized if alarm call recipients discriminate among signalers, and weight their response accordingly. For juvenile ground squirrels, we predicted that the trade-off between foraging and vigilance could be optimized via selective response to alarm calls emitted by their own dam, and/or neighboring colony members over calls broad- cast by less familiar conspecifics. Alarm calls of adult female Richardson＇s ground squirrels were elicited in the field using a predator model and recorded on digital audio tape. Free-living focal juveniles were subjected to playbacks of a call of their mother, and on a separate occasion a call from either another adult female from their own colony, or an adult female from another colony. Neither immediate postural responses and escape behavior, nor the duration of vigilance manifested by juveniles differed with exposure to alarm calls of the three adult female signaler types. Thus, juveniles did not respond preferentially to alarm calls emitted by their mothers or colony members, likely reflecting the high cost of ignoring alarm signals where receivers have had limited opportunity to establish past signaler reliability [Current Zoology 58 （5）： 773-780, 2012].
基金Natural Sciences and Engineering Research Council of Canada(NSERC)Postgraduate Scholarship awarded to L.J.N.and a NSERC Discovery Grant(154271)awarded to J.F.H.
文摘In grassland ecosystems,burrowing mammals create disturbances,providing habitat for animal species and increasing plant community diversity.We investigated whether seedling assemblages on Richardson's ground squirrel Urocitellus richardsonii mounds result from seed rearrangement or environmental changes that favor germination of certain species over others.To test whether ground squirrels rearrange the seed bank by burrowing,we compared seed compositions among mounds,burrows,and undisturbed soil.To test whether ground squirrels change environmental conditions,we compared soil nitrate and bare ground cover on and off mounds.We also compared seedlings that germinated on mounds with seedlings that germinated on artificial disturbances from which we removed aboveground vegetation.Soil nitrate and bare ground cover were significantly higher on mounds than artificial disturbances.While seed richness and abundance did not differ among mounds,burrows,and undisturbed soil,seedling richness was reduced on mounds relative to artificial disturbances.Burrowing disturbance favors seedlings that can capitalize on bare ground availability but are less able to immobilize nitrate,as opposed to perennial species that immobilize more nitrate but take longer to establish.Our results suggest that Richardson's ground squirrels act as ecosystem engineers,although future research following succession on ground squirrel mounds is necessary to understand how they influence plant communities past the seedling stage.
基金supported by LG Evergreen Foundation,Republic of Korea
文摘In this study, we examined the use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in three coniferous and mixed forests in Gangwon Province, South Korea. Six hundred and twelve boxes with different sized entry holes (ranging from 3 to 7 cm in diameter) were placed in the forests between 2004 and 2009. Pteromys volans used nine boxes in the coniferous forests and two boxes in the mixed forests. The squirrels only used boxes with entrance holes measuring 3.5, 4, and 5 cm in diameter, showing a strong and moderate preference for boxes with 5 and 4-cm holes, respectively, and a strong avoidance for boxes with 3- and 7-cm holes. Therefore, we suggest placing artificial nest boxes with entrance holes 5 cm in diameter to encourage breeding activity. Most nests made in the artificial boxes were composed of fibrous materials from woody vines. We recommend placing artificial nest boxes with holes of 5-cm diameter in coniferous forests, which support dense populations of P. volans, to survey whether this approach would positively affect the breeding habits and population maintenance of this species.
文摘Oaks(Quercus spp.)provide an important food source for many wildlife species throughout the fall and winter.Most research evaluating oak masting patterns and the subsequent behavioral responses of wildlife focuses on the annual temporal scale.However,patterns in masting at the seasonal temporal scale may be important for wildlife behavior.We designed a study quantifying seasonal oak masting patterns of 3 oak species(water oak,Q.nigra;laurel oak,Q.laurifolia;and swamp chestnut oak,Q.michauxii)and linking those patterns to visitation and feeding behavior of 3 primary consumers(white-tailed deer,Odocoileus virginianus;gray squirrel,Sciurus carolinensis;and raccoon,Procyon lotor).We used seed traps to monitor the seasonal masting pattern of 205 trees in the fall of 2021 and 2022 and used camera traps concurrently to monitor wildlife behavior associated with a subset of 30 trees.Seasonal masting patterns differed between oak species both within a season and across years,and the timing of mast varied within oak species across years.White-tailed deer tended to visit swamp chestnut oak as the number of acorns increased and consumed their acorns.Gray squirrels and raccoons tended to visit laurel oak and consume water oak acorns with gray squirrels being more likely to consume as the number of acorns increased.Our results indicate that evaluating acorn production at multiple temporal scales may be necessary to fully understand oak masting relationships with wildlife.Furthermore,differences in wildlife behavior based on oak species may have important implications for oak regeneration.
基金supported by a Discovery grant from the Natural Sciences and Engineering Research Council (NSERC) of Canada (Grant No. 6793)supported by the NSERC postgraduate fellowships
文摘Micro RNAs（mi RNAs） are small non-coding RNAs that are important in regulating metabolic stress. In this study, we determined the expression and structural characteristics of 20 mi RNAs in brown（BAT） and white adipose tissue（WAT） during torpor in thirteen-lined ground squirrels. Using a modified stem-loop technique, we found that during torpor, expression of six mi RNAs including let-7a, let-7b, mi R-107, mi R-150, mi R-222 and mi R-31 was significantly downregulated in WAT（P 〈 0.05）, which was 16%–54% of euthermic non-torpid control squirrels,whereas expression of three mi RNAs including mi R-143, mi R-200 a and mi R-519 d was found to be upregulated by 1.32–2.34-fold. Similarly, expression of more mi RNAs was downregulated in BAT during torpor. We detected reduced expression of 6 mi RNAs including mi R-103 a, mi R-107, mi R-125 b, mi R-21, mi R-221 and mi R-31（48%–70% of control）, while only expression of mi R-138 was significantly upregulated（2.91 ± 0.8-fold of the control, P 〈 0.05）. Interestingly,mi RNAs found to be downregulated in WAT during torpor were similar to those dysregulated in obese humans for increased adipogenesis, whereas mi RNAs with altered expression in BAT during torpor were linked to mitochondrial b-oxidation. mi RPath target prediction analysis showed that mi RNAs downregulated in both WAT and BAT were associated with the regulation of mitogen-activated protein kinase（MAPK） signaling, while the mi RNAs upregulated in WAT were linked to transforming growth factor b（TGFb） signaling. Compared to mouse sequences, no unique nucleotide substitutions within the stem-loop region were discovered for the associated pre-mi RNAs for the mi RNAs used in this study, suggesting no structure-influenced changes in pre-mi RNA processing efficiency in the squirrel. As well, the expression of mi RNA processingenzyme Dicer remained unchanged in both tissues during torpor. Overall, our findings suggest that changes of mi RNA expression in adipose tissues may be linked to distinct biological roles in WAT and BAT during hibernation and may involve the regulation of signaling cascades.
基金supported by the National Natural Science Foundation of China(31872320,21806010)the Young Scientist Start-up funding of Beijing Forestry University(BLX201714).
文摘The purpose of this study was to explore the variations in the circulating leptin concentrations of the wild ground squirrels in relation to seasonal changes in testicular activities.Hematoxylin-eosin staining showed all types of elongated spermatids and spermatogenic cells existed in the testis in April,while the primary spermatocytes and spermatogonia were most advanced stages of germ cells in June.In addition,the primary spermatocytes,secondary spermatocytes,and spermatogonia were most advanced stages of germ cells in September.The highest circulating leptin concentration was consistent with the maximum body weight results from accumulation of adipose tissue in September.The mRNA expression level of leptin receptor(Ob-R)and STAT3 was lowest in June,raised in September,and remained increased in April.Ob-R and STAT3 were stronger staining in the Leydig cells in July.Moreover,the concentrations of testosterone(T)showed the maximum values in April,the minimum values in June,and significant increases in September.Furthermore,it is worth noting that the levels of T increased with the mRNA levels of Ob-R,STAT3,StAR,and testicular steroidogenic enzymes(3β-HSD,P450c17,and P450scc).Moreover,RNA-seq analyses of testis during the different periods showed that a total of 4209 genes were differ-entially expressed genes(DEGs);further analysis revealed that DEGs related with the Jak/STAT pathways and reproduction were altered.Taken together,the results suggested that the leptin regulated testicular function through the Jak/STAT pathways and testicular steroidogenic factor expressions.
文摘Grey squirrels(Sciurus carolinensis)are an invasive species in Britain and Italy.They have replaced native red squirrels(Sciurus vulgaris)throughout most of Britain,and cause damage to trees.Currently,lethal control is used to manage grey squirrel populations in Britain,but nonlethal methods might be more acceptable to the public.One such method is contraception with 20,25-diazacholesterol dihydrochloride(DiazaCon^(TM)).DiazaCon^(TM) inhibits the conversion of desmosterol to cholesterol,resulting in increasing desmosterol concentrations and decreasing cholesterol concentrations.Because cholesterol is needed for the synthesis of steroid reproductive hormones,such as progesterone and testosterone,inhibition of cholesterol synthesis indirectly inhibits reproduction.Desmosterol is used as a marker of efficacy in laboratory studies with species that do not reproduce readily in captivity.Grey squirrels were gavaged with a DiazaCon^(TM) solution for 2 days,and then fed DiazaCon^(TM)-coated peanuts for an additional 8 days at target doses of 50 and 100 mg DiazaCon^(TM) per kg body weight.There was a significant difference in cholesterol concentrations in the treatment groups compared to the control group.Cholesterol was reduced by≥40%for 2 months in both treatment groups.There were no differences among groups with respect to blood chemistry and hematology parameters,and mean values are reported.The mean overall dose of DiazaCon^(TM) received was 29.0±1.6 and 55.3±4.3 mg/kg in the low(50 mg/kg)and high dose(100 mg/kg)groups,respectively.DiazaCon^(TM) might provide an effective,acceptable alternative to lethal control.
基金supported by the Russian Science Foundation,project number 22-24-00610,https://rscf.ru/project/22-24-00610/.
文摘Juvenile survival is a key life-history influence on population dynamics and adaptive evolution.We analyzed the effects of individual chara-cteristics,early environment,and maternal investment on juvenile survival in a large solitary hibernating rodent-yellow ground squirrel Spermophilus fulvus using Cox mixed-effects models.Only 48%of weaned pups survived to dispersal and 17%survived to hibernation.Early life expectancy was primarily determined by individual characteristics and,to a lesser extent,by the early environment.The strongest and pos-itive predictor of juvenile survival was body mass which crucially affected mortality immediately after weaning.Males suffered higher mortality than females after the onset of dispersal;however,the overall difference between sexes was partly masked by high rates of mortality in the first days after emergence in both sexes.Later emerged juveniles had lower life expectancy than the earliest pups.The overall effect of local juvenile density was positive.Prolonged lactation did not enhance juvenile survival:Pups nursed longer survived shorter than the young nursed for a shorter period.Our findings support the hypothesis that females of S.fulvus cannot effectively regulate maternal expenditures to mitigate the effects of unfavorable conditions on their offspring.The strategy to deal with seasonal time constraints on life history in female S.fulvus suggests an early termination of maternal care at the cost of juvenile quality and survival.This female reproductive strategy corresponds to a"fast-solitary"life of folivorous desert-dwelling S.fulvus and other solitary ground squirrels with prolonged hibernation.
文摘The harmonics that appear in the squirrel cage asynchronous machine have been discussed in great detail in the literature for a long time. However, the systematization of the phenomenon is still pending, so we made an attempt to fill this gap in the previous parts of our study by elaborating formulas for calculation of parasitic torques. It was a general demand among those who work in this field towards the author to verify his formulas with measurements. In the literature, it seems,only one detailed, purposeful series of measurements has been published so far, the purpose of which was to investigate the effect of the number of rotor slots on the torque-speed characteristic curve of the machine. The main goal of this study is to verify the correctness of the formulas by comparing them with the referred series of measurements. Relying on this, the expected synchronous parasitic torques were developed for the frequently used rotor slot numbers-as a design guide for the engineer.Thus, together with our complete table for radial magnetic pull published in our previous work, the designer has all the principles, data and formulas available for the right number of rotor slots for his given machine and for the drive system. This brings this series of papers to an end.
基金supported by the Key Research and Development Project of Hubei Province(Nos.2020BAB114 and 2023BAB094).
文摘In the manufacturing industry,reasonable scheduling can greatly improve production efficiency,while excessive resource consumption highlights the growing significance of energy conservation in production.This paper studies the problem of energy-efficient distributed heterogeneous permutation flowshop problem with variable processing speed(DHPFSP-VPS),considering both the minimum makespan and total energy consumption(TEC)as objectives.A discrete multi-objective squirrel search algorithm(DMSSA)is proposed to solve the DHPFSPVPS.DMSSA makes four improvements based on the squirrel search algorithm.Firstly,in terms of the population initialization strategy,four hybrid initialization methods targeting different objectives are proposed to enhance the quality of initial solutions.Secondly,enhancements are made to the population hierarchy system and position updating methods of the squirrel search algorithm,making it more suitable for discrete scheduling problems.Additionally,regarding the search strategy,six local searches are designed based on problem characteristics to enhance search capability.Moreover,a dynamic predator strategy based on Q-learning is devised to effectively balance DMSSA’s capability for global exploration and local exploitation.Finally,two speed control energy-efficient strategies are designed to reduce TEC.Extensive comparative experiments are conducted in this paper to validate the effectiveness of the proposed strategies.The results of comparing DMSSA with other algorithms demonstrate its superior performance and its potential for efficient solving of the DHPFSP-VPS problem.
文摘In polymorphic mammalian species that display multiple color forms, those with dark, or melanic pelage would be prone to overheating, especially if they live in warm climates, because their fur absorbs solar energy at a higher rate. However, experimental studies indicate that certain physical properties of fur of dark individuals appear to prevent, or minimize heat stress, although it is not clear what properties do so. Here, we tested the possibility that black-furred individuals simply have shorter or thinner hair fibers, which would create a lighter （in terms of weight） coat or one that allows greater air flow for evaporative coo- ling. We examined museum specimens of eastern fox squirrels Sciurus niger, a species native to the United States and one that displays brown, grey or all-black pelage color, and used image analysis procedures to quantify hairs from the dorsal surface and tail. From examination of 43 specimens （19 brown, 9 black and 15 grey）, and 1,720 hairs, we found no significant difference in hair lengths across color morphs, but significant differences in hair fiber widths. Black squirrels had thinner body hairs than other forms （7% thinner）, but thicker tail hairs （9% thicker） than the others. Given that the dorsal surface would be directly exposed to solar radiation, we interpret this to be an adaptation to prevent heat stress during the day. The thicker tail hairs may be an adapta- tion for nighttime thermoregulation, since squirrels sleep with their tails wrapped around their bodies. These results add to a growing literature body of the functional significance of mammalian pelage [Current Zoology 57 （6）： 731-736, 2011].
基金supported by the National Natural Science Foundation of China(Nos.31472013 and 31772453 to W.L.).
文摘Hole-nesting tits belonging to the family Paridae produce a hissing display that resembles the exhalatory hiss of a snake.When a predatory animal enters the nest hole of a tit,tits often hiss vigorously,while lunging their head forward and shaking their wings and tail,until the intruder retreats.We assessed the acoustic similarity between such hiss calls from 6 species of tits,snake hisses,and tit syllables used in alarm vocalizations,as well as white noise as a control.Tit hiss calls showed a high degree of similarity with snake hisses from 3 different snake families.Tit hisses had lower similarity to syllable alarm calls,suggesting convergence of tit hisses in their spectral structure.Hiss calls would only be effective in protecting nest boxes if nest predators responded to these calls.In order to test this hypothesis,we trained individual Swinhoe’s striped squirrels,Tamiops swinhoei hainanus,a common predator of egg and nestling tits,to feed at feeders in proximity to nest boxes.We compared the aversive response of squirrels to tit’s hiss calls and white noise,presented in random order.Squirrels showed a higher degree of avoidance of feeders when hiss calls were played back than when white noise was presented.In conclusion,our study suggests that hole-nesting birds have evolved convergent snake-like hiss calls,and that predators avoid to prey on the contents of nest boxes from which snake-like hisses emerge.
基金supported by the National Natural Science Foundation of China(32171487)State Forestry and Grassland Administration Bureau of ChinaPostdoctoral Research Grants at the Central South University of Forestry and Technology(45220003).
文摘The Himalayan marmot Marmota himalayana is widely distributed across the Qinghai-Tibetan Plateau and lives in social groups,yet the mating system of this highly social marmot species is unknown.In this study,the genetic mating system of Himalayan marmots was inves-tigated using microsatellite markers to determine which mating strategies individuals employ.Results revealed that both monogamous and polygamous mating relationships occur in our study population,indicating that the genetic mating system of this marmot species is promiscuity.This study presents the first genetic evidence on the mating system for Himalayan marmots,yet indicates that further studies employing both a genetic and behavioral framework are needed to better understand the social structure and reproductive biology of this marmotspecies.
