1
|
Cloutier Z, Festa-Bianchet M, Pelletier F. Direct and indirect effects of cougar predation on bighorn sheep fitness. Ecology 2024; 105:e4374. [PMID: 39031035 DOI: 10.1002/ecy.4374] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2023] [Revised: 02/05/2024] [Accepted: 04/14/2024] [Indexed: 07/22/2024]
Abstract
Predation has direct effects on prey population dynamics through mortality, and it can induce indirect effects through fear. The indirect effects of predation have been documented experimentally, but few studies have quantified them in nature so that their role in prey population dynamics remains controversial. Given the expanding or reintroduced populations of large predators in many areas, the quantification of indirect effects of predation is crucial. We sought to evaluate the direct and indirect fitness effects of intense cougar (Puma concolor) predation using 48 years of data on marked bighorn sheep (Ovis canadensis) on Ram Mountain, Alberta, Canada. We compared years of intense cougar predation with years with no or occasional cougar predation. We first quantified the effects of predation on neonatal, weaning, and overwinter lamb survival, three metrics potentially affected by direct and indirect effects. We then investigated the possible indirect effects of intense cougar predation on lamb production, female summer mass gain, and lamb mass at weaning. We found strong effects of cougar predation on lamb survival, lamb production, and seasonal mass gain of lambs and adult females. In years with high predation, neonatal, weaning, and overwinter lamb survival declined by 18.4%, 19.7% and 20.8%, respectively. Indirect effects included a 14.2% decline in lamb production. Female summer mass gain decreased by 15.6% and lamb mass at weaning declined by 8.0% in years of intense cougar predation. Our findings bring key insights on the impacts of predation on prey fitness by reporting moderate to large effects on recruitment and illustrate the importance of indirect effects of predation on population dynamics.
Collapse
Affiliation(s)
- Zachary Cloutier
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
| | - Marco Festa-Bianchet
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
- Centre d'études nordiques, Québec City, Quebec, Canada
| | - Fanie Pelletier
- Département de Biologie, Université de Sherbrooke, Sherbrooke, Quebec, Canada
- Centre d'études nordiques, Québec City, Quebec, Canada
| |
Collapse
|
2
|
Wang Z, Yan J, Martin A, Brunton DH, Qu J, He JS, Ji W, Nan Z. Alpine grassland degradation intensifies the burrowing behavior of small mammals: evidence for a negative feedback loop. Integr Zool 2024; 19:240-252. [PMID: 37243518 DOI: 10.1111/1749-4877.12730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Globally, grassland degradation is an acute ecological problem. In alpine grassland on the Tibetan Plateau, increased densities of various small mammals in degraded grassland are assumed to intensify the degradation process and these mammals are subject to lethal control. However, whether the negative impact of small mammals is solely a result of population size or also a result of activity and behavior has not been tested. In this study, we use plateau pika as a model to compare population size, core area of colony, and the number of burrow entrances and latrines between lightly and severely degraded grassland. We test whether the alleged contribution of pika to grassland degradation is a result of increased population size or increased burrowing activities of individuals in response to lower food abundance. We found that grassland degradation resulted in lower plant species richness, plant height, and biomass. Furthermore, the overall population size of pika was not significantly affected by location in lightly and severely degraded grassland. However, pika core areas in severely grassland degradation were significantly larger and had significantly higher densities of burrows and latrines. Our study provides convincing evidence that habitat-induced changes in the behavior of small, burrowing mammals, such as pika, can exacerbate grassland degradation. This finding has significant implications for managing small mammals and restoring degraded grassland ecosystems.
Collapse
Affiliation(s)
- Zaiwei Wang
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
| | - Jiawen Yan
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
| | - Amy Martin
- Manaaki Whenua-Landcare Research, Lincoln, New Zealand
| | - Dianne H Brunton
- School of Natural Sciences, Massey University (Albany Campus), Auckland, New Zealand
| | - Jiapeng Qu
- Key Laboratory of Adaptation and Evolution of Plateau Biota, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
- Qinghai Haibei National Field Research Station of Alpine Grassland Ecosystem, Northwest Institute of Plateau Biology, Chinese Academy of Sciences, Xining, China
| | - Jin-Sheng He
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
- Institute of Ecology, College of Urban and Environmental Sciences, and Key Laboratory for Earth Surface Processes of the Ministry of Education, Peking University, Beijing, China
| | - Weihong Ji
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
- School of Natural Sciences, Massey University (Albany Campus), Auckland, New Zealand
| | - Zhibiao Nan
- State Key Laboratory of Herbage Improvement and Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, China
| |
Collapse
|
3
|
Zhou R, Hua R, Tang Z, Hua L. Group-living decrease predation risk of individual: Evidence from behavior, hormones and reproduction of plateau pika. Front Ecol Evol 2023. [DOI: 10.3389/fevo.2023.1037377] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/08/2023] Open
Abstract
Extensive research confirms that abiotic stressors like predation risk can profoundly affect animal condition. However, there is a lack of experimental research assessing the suite of physiological responses to risk. We increased predation risk in free-living plateau pikas (Ochotona curzoniae) by simulating natural chases using a model predator (UAV: unmanned aerial vehicle) and monitored behavior, physiology, and reproduction of pikas. We found that: Predation risk affects the body weight of plateau pika under different population density stress, but the effect is not significant. Compared with the non-predation risk treatment (control), the plateau pika under high population density stress mainly responded to the risk of predation by reducing the foraging time and increasing the vigilance time, while plateau pikas under low population density pressure not only reduce foraging time and appropriately increase vigilance time, but also focus on increasing the concealing time in the burrows. The corticosterone (CORT), cortisol and thyroid (T4) level of plateau pika with low population density under the predation risk was significantly higher than those in the control, and the testosterone (T), progesterone (PROG), leptin (LEP) and testicular weight of plateau pika with low population density in the predation risk was significantly lower than those in the control. There was no difference in the litter size of female pika between predation risk treatments and control. Broadly, our result show that predation risk had significant effects on the behavior, physiology and reproduction of plateau pikas with low population density, but had no significant effect with high population density, and the response of male plateau pika to predation risk was greater than that of female. Therefore, the prevention of plateau pika should focus on the control of population density and the protection of predators, so as to avoid the failure of ecological prevention methods such as natural enemies due to the increase of population density.
Collapse
|
4
|
Matzke CC, Kusch JM, Janz DM, Lane JE. Perceived predation risk predicts glucocorticoid hormones, but not reproductive success in a colonial rodent. Horm Behav 2022; 143:105200. [PMID: 35617896 DOI: 10.1016/j.yhbeh.2022.105200] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/29/2021] [Revised: 05/09/2022] [Accepted: 05/11/2022] [Indexed: 11/29/2022]
Abstract
The Cort-Adaptation hypothesis suggests that elevated glucocorticoids (GCs) can facilitate an adaptive response to environmental and physiological challenges. Most previous studies have focused on avian species, which may limit their generalizability to mammals, where lactation is known to be a major physiological challenge. Furthermore, the effect of predation risk on GC levels has not been tested in the Cort-Adaptation hypothesis. We sought to test this hypothesis in a colonial prey species, black-tailed prairie dogs (Cynomys ludovicianus). We predicted that individuals located near fewer neighboring conspecifics would perceive an increased risk of predation and, in turn, have increased GCs (measured through hair cortisol concentration (HCC)) and reduced annual reproductive success compared to more centrally located individuals. We also investigated other putative influences on HCC: age, lactation status, body condition, and season of hair growth. Levels of vigilance behavior were higher for those with fewer neighboring conspecifics, suggesting variation in perceived risk of predation. Further, the risk of predation appeared to represent a chronic, detrimental stressor as evidenced by a significant increase in HCC for prairie dogs with fewer neighbors. Lactation status and season also influenced HCC. We found support for the Cort-Adaptation hypothesis where increased HCC during the reproductive season correlated with whether a female produced a litter, but not litter size, suggesting a minimum threshold of GCs is required for successful reproduction in this species. Our work illustrates that HCC may operate as an indicator of perceived predation risk, but care should be taken to consider the variety of factors influencing GC homeostasis, in particular lactation, when drawing conclusions using HCC as a marker of long-term stress.
Collapse
Affiliation(s)
| | - Jillian M Kusch
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| | - David M Janz
- Department of Veterinary Biomedical Sciences, University of Saskatchewan, Saskatoon, SK, Canada
| | - Jeffrey E Lane
- Department of Biology, University of Saskatchewan, Saskatoon, SK, Canada
| |
Collapse
|
5
|
Abuaish S, Lavergne SG, Hing B, St-Cyr S, Spinieli RL, Boonstra R, McGowan PO. Sex-specific maternal programming of corticosteroid-binding globulin by predator odour. Proc Biol Sci 2021; 288:20211908. [PMID: 34847769 PMCID: PMC8634628 DOI: 10.1098/rspb.2021.1908] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Accepted: 11/09/2021] [Indexed: 12/24/2022] Open
Abstract
Predation is a key organizing force in ecosystems. The threat of predation may act to programme the endocrine hypothalamic-pituitary-adrenal axis during development to prepare offspring for the environment they are likely to encounter. Such effects are typically investigated through the measurement of corticosteroids (Cort). Corticosteroid-binding globulin (CBG) plays a key role in regulating the bioavailability of Cort, with only free unbound Cort being biologically active. We investigated the effects of prenatal predator odour exposure (POE) in mice on offspring CBG and its impact on Cort dynamics before, during and after restraint stress in adulthood. POE males, but not females, had significantly higher serum CBG at baseline and during restraint and lower circulating levels of Free Cort. Restraint stress was associated with reduced liver transcript abundance of SerpinA6 (CBG-encoding gene) only in control males. POE did not affect SerpinA6 promoter DNA methylation. Our results indicate that prenatal exposure to a natural stressor led to increased CBG levels, decreased per cent of Free Cort relative to total and inhibited restraint stress-induced downregulation of CBG transcription. These changes suggest an adaptive response to a high predator risk environment in males but not females that could buffer male offspring from chronic Cort exposure.
Collapse
Affiliation(s)
- Sameera Abuaish
- Department of Basic Sciences, College of Medicine, Princess Nourah bint Abdulrahman University, PO Box 84428, Riyadh 11671, Saudi Arabia
- Department of Biological Sciences and Centre for Environmental Epigenetics and Development, University of Toronto Scarborough Campus, 1265 Military Trail, Toronto, Ontario, Canada
- Departments of Cell and Systems Biology, Psychology, and Physiology, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada
| | - Sophia G. Lavergne
- Department of Biological Sciences and Centre for Environmental Epigenetics and Development, University of Toronto Scarborough Campus, 1265 Military Trail, Toronto, Ontario, Canada
| | - Benjamin Hing
- Department of Molecular Physiology and Biophysics, University of Iowa, 51 Newton Road, Bowen Science Building 6-509, Iowa City, IA 52242, USA
| | - Sophie St-Cyr
- Department of Biological Sciences and Centre for Environmental Epigenetics and Development, University of Toronto Scarborough Campus, 1265 Military Trail, Toronto, Ontario, Canada
- Departments of Cell and Systems Biology, Psychology, and Physiology, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada
- The Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Richard L. Spinieli
- Psychobiology Graduate Program, School of Philosophy, Science and Literature of Ribeirão Preto of the University of São Paulo, Ribeirão Preto, São Paulo, Brazil
| | - Rudy Boonstra
- Department of Biological Sciences and Centre for Environmental Epigenetics and Development, University of Toronto Scarborough Campus, 1265 Military Trail, Toronto, Ontario, Canada
| | - Patrick O. McGowan
- Department of Biological Sciences and Centre for Environmental Epigenetics and Development, University of Toronto Scarborough Campus, 1265 Military Trail, Toronto, Ontario, Canada
- Departments of Cell and Systems Biology, Psychology, and Physiology, University of Toronto, 1265 Military Trail, Toronto, Ontario, Canada
| |
Collapse
|
6
|
Lavergne SG, Krebs CJ, Kenney AJ, Boutin S, Murray D, Palme R, Boonstra R. The impact of variable predation risk on stress in snowshoe hares over the cycle in North America's boreal forest: adjusting to change. Oecologia 2021; 197:71-88. [PMID: 34435235 DOI: 10.1007/s00442-021-05019-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2021] [Accepted: 08/16/2021] [Indexed: 11/26/2022]
Abstract
The boreal forest is one of the world's ecosystems most affected by global climate warming. The snowshoe hare, its predators, and their population dynamics dominate the mammalian component of the North American boreal forest. Our past research has shown the 9-11-year hare cycle to be predator driven, both directly as virtually all hares that die are killed by their predators, and indirectly through sublethal risk effects on hare stress physiology, behavior, and reproduction. We replicated this research over the entire cycle by measuring changes in predation risk expected to drive changes in chronic stress. We examined changes in hare condition and stress axis function using a hormonal challenge protocol in the late winter of 7 years-spanning all phases of the cycle from the increase through to the low (2014-2020). We simultaneously monitored changes in hare abundance as well as those of their primary predators, lynx and coyotes. Despite observing the expected changes in hare-predator numbers over the cycle, we did not see the predicted changes in chronic stress metrics in the peak and decline phases. Thus, the comprehensive physiological signature indicative of chronic predator-induced stress seen from our previous work was not present in this current cycle. We postulate that hares may now be increasingly showing behavior-mediated rather than stress-mediated responses to their predators. We present evidence that increases in primary productivity have affected boreal community structure and function. We speculate that climate change has caused this major shift in the indirect effects of predation on hares.
Collapse
Affiliation(s)
- Sophia G Lavergne
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada
| | - Charles J Krebs
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Alice J Kenney
- Department of Zoology, University of British Columbia, Vancouver, BC, Canada
| | - Stan Boutin
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Dennis Murray
- Department of Biology, Trent University, Peterborough, ON, Canada
| | - Rupert Palme
- Department of Biomedical Sciences, University of Veterinary Medicine, Vienna, Austria
| | - Rudy Boonstra
- Department of Biological Sciences, University of Toronto Scarborough, Toronto, ON, Canada.
| |
Collapse
|
7
|
Surviving winter on the Qinghai-Tibetan Plateau: Pikas suppress energy demands and exploit yak feces to survive winter. Proc Natl Acad Sci U S A 2021; 118:2100707118. [PMID: 34282012 DOI: 10.1073/pnas.2100707118] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
The Qinghai-Tibetan Plateau, with low precipitation, low oxygen partial pressure, and temperatures routinely dropping below -30 °C in winter, presents several physiological challenges to its fauna. Yet it is home to many endemic mammalian species, including the plateau pika (Ochotona curzoniae). How these small animals that are incapable of hibernation survive the winter is an enigma. Measurements of daily energy expenditure (DEE) using the doubly labeled water method show that pikas suppress their DEE during winter. At the same body weight, pikas in winter expend 29.7% less than in summer, despite ambient temperatures being approximately 25 °C lower. Combined with resting metabolic rates (RMRs), this gives them an exceptionally low metabolic scope in winter (DEE/RMRt = 1.60 ± 0.30; RMRt is resting metabolic rate at thermoneutrality). Using implanted body temperature loggers and filming in the wild, we show that this is achieved by reducing body temperature and physical activity. Thyroid hormone (T3 and T4) measurements indicate this metabolic suppression is probably mediated via the thyroid axis. Winter activity was lower at sites where domestic yak (Bos grunniens) densities were higher. Pikas supplement their food intake at these sites by eating yak feces, demonstrated by direct observation, identification of yak DNA in pika stomach contents, and greater convergence in the yak/pika microbiotas in winter. This interspecific coprophagy allows pikas to thrive where yak are abundant and partially explains why pika densities are higher where domestic yak, their supposed direct competitors for food, are more abundant.
Collapse
|
8
|
Wei W, Zhen Q, Tang Z, Oosthuizen MK. Risk assessment in the plateau pika (Ochotona curzoniae): intensity of behavioral response differs with predator species. BMC Ecol 2020; 20:41. [PMID: 32680498 PMCID: PMC7368780 DOI: 10.1186/s12898-020-00309-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2019] [Accepted: 07/13/2020] [Indexed: 11/24/2022] Open
Abstract
Background The ability of a prey species to assess the risk that a predator poses can have important fitness advantages for the prey species. To better understand predator–prey interactions, more species need to be observed to determine how prey behavioral responses differ in intensity when approached by different types of predators. The plateau pika (Ochotona curzoniae) is preyed upon by all predators occurring in its distribution area. Therefore, it is an ideal species to study anti-predator behavior. In this study, we investigated the intensity of anti-predator behavior of pikas in response to visual cues by using four predator species models in Maqu County on the eastern Qinghai-Tibetan Plateau. Results The behavioral response metrics, such as Flight Initiation Distance (FID), the hiding time and the percentage of vigilance were significantly different when exposed to a Tibetan fox, a wolf, a Saker falcon and a large-billed crow, respectively. Pikas showed a stronger response to Saker falcons compared to any of the other predators. Conclusions Our results showed that pikas alter their behavioral (such as FID, the hiding time and the vigilance) response intensity to optimally balance the benefits when exposed to different taxidermy predator species models. We conclude that pikas are able to assess their actual risk of predation and show a threat-sensitive behavioral response.
Collapse
Affiliation(s)
- Wanrong Wei
- Key Laboratory of Southwest China Wildlife Resources Conservation, College of life Sciences, China West Normal University, Nanchong, 637009, China. .,State Key Laboratory of Grassland Agro-Ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730200, China.
| | - Qiaoyan Zhen
- China West Normal University, Nanchong, 637009, China
| | - Zhongmin Tang
- Gannan Grassland Workstation in Gansu Province, Hezuo, 747000, China
| | - Maria K Oosthuizen
- Department of Zoology and Entomology, University of Pretoria, Private Bag X20, Hatfield, 0028, South Africa.,Mammal Research Institute, University of Pretoria, Hatfield, 0028, South Africa
| |
Collapse
|
9
|
Dulude‐de Broin F, Hamel S, Mastromonaco GF, Côté SD. Predation risk and mountain goat reproduction: Evidence for stress‐induced breeding suppression in a wild ungulate. Funct Ecol 2020. [DOI: 10.1111/1365-2435.13514] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Frédéric Dulude‐de Broin
- Département de biologie Université Laval Québec City QC Canada
- Centre d'études nordiquesQuébec City QC Canada
| | - Sandra Hamel
- Département de biologie Université Laval Québec City QC Canada
- Department of Arctic and Marine Biology Faculty of Biosciences, Fisheries, and Economics UiT The Arctic University of Norway Tromsø Norway
| | | | - Steeve D. Côté
- Département de biologie Université Laval Québec City QC Canada
- Centre d'études nordiquesQuébec City QC Canada
| |
Collapse
|
10
|
Humphrey EA, Crespi E, Travis J. Under pressure: Short‐ and long‐term response to predation varies in two populations of a live‐bearing fish. Ethology 2019. [DOI: 10.1111/eth.12996] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Eve A. Humphrey
- Department of Biological Science Florida State University Tallahassee FL USA
| | - Erica Crespi
- School of Biological Sciences Washington State University Pullman WA USA
| | - Joseph Travis
- Department of Biological Science Florida State University Tallahassee FL USA
| |
Collapse
|
11
|
Differential antipredatory responses in the tuco-tuco (Ctenomys talarum) in relation to endogenous and exogenous changes in glucocorticoids. J Comp Physiol A Neuroethol Sens Neural Behav Physiol 2019; 206:33-44. [PMID: 31784830 DOI: 10.1007/s00359-019-01384-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 10/11/2019] [Accepted: 11/19/2019] [Indexed: 10/25/2022]
Abstract
Glucocorticoids participate in the behavioral and physiological responses generated under stressful circumstances coming from different sources-physical and/or psychological. In mammals, the increases of these hormones are mediated by the activation of the hypothalamic-pituitary-adrenal axis. This response occurs after exposure to novel and unpredictable situations that lead to the loss of homeostasis, for example, a direct encounter with predators or their cues. However, the relationship between the physiological and behavioral responses is still a complex issue in vertebrates. We evaluate the effects of an experimental manipulation of glucocorticoid levels on the generation of the behavioral and physiological response to stress by predation in the subterranean rodent C. talarum. We found that when tuco-tucos encountered predator cues-fur odor, and largely, immobilization-they responded physiologically by secreting cortisol. This response was accompanied by an associated behavioral response. However, when the increase in plasma cortisol originated exogenously by the injection of cortisol, a behavioral response was not observed. Finally, inhibition of glucocorticoids' synthesis was effective in weakening the behavioral effects produced by immobilization. In conclusion, in tuco-tucos, predator cues act as stress factors that trigger differential increases in plasma cortisol and a behavioral response associated with the appearance of anxiety states.
Collapse
|