Linking social environment and stress physiology in feral mares (Equus caballus): group transfers elevate fecal cortisol levels.
Abstract: Feral horses (Equus caballus) have a complex social structure, the stability of which is important to their overall health. Behavioral and demographic research has shown that decreases in group (or band) stability reduce female fitness, but the potential effects on the physiological stress response have not been demonstrated. To fully understand how band stability affects group-member fitness, we need to understand not only behavioral and demographic, but also physiological consequences of decreases to that stability. We studied group changes in feral mares (an activity that induces instability, including both male and female aggression) on Shackleford Banks, NC. We found that mares in the midst of changing groups exhibit increased fecal cortisol levels. In addition, mares making more group transfers show higher levels of cortisol two weeks post-behavior. These results offer insights into how social instability is integrated into an animal's physiological phenotype. In addition, our results have important implications for feral horse management. On Shackleford Banks, mares contracepted with porcine zona pellucida (PZP) make approximately 10 times as many group changes as do untreated mares. Such animals may therefore be at higher risk of chronic stress. These results support the growing consensus that links between behavior and physiological stress must be taken into account when managing for healthy, functional populations.
Copyright © 2013 Elsevier Inc. All rights reserved.
Publication Date: 2013-11-22 PubMed ID: 24275609DOI: 10.1016/j.ygcen.2013.11.012Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.
This study examines the relationship between social stability and stress levels in feral horses, finding that mares changing social groups display elevated cortisol levels, a marker of stress. This highlights the need to consider such links when managing feral horse populations.
Objective and Importance of the Study
- This research aims to investigate the effects of social stability, specifically in terms of changes within groups, on the stress response of feral horses, specifically mares.
- The study highlights the importance of understanding not just the behavioral and social elements of animal groups, but also the physiological responses affiliated to changes in their environments.
- Both behavioral and physiological factors contribute to the overall fitness and health of individuals within these animal populations.
- The study also bears implications for future management of feral horse populations and the importance of accounting for stress responses in maintaining healthy populations.
Methodology
- The researchers carried out this study on Shackleford Banks, North Carolina, where they monitored changes within groups of feral mare horses. This activity brings about instability in the herd and increases aggressive behavior in both males and females.
- The team employed fecal cortisol levels as a marker of stress, noting that mares in the process of changing groups demonstrated increased cortisol levels.
Key Findings
- The study found a clear link between group transfers, or social stability, and physiological stress responses in the form of elevated cortisol levels.
- Further, it was found that mares making more frequent group transfers maintained higher cortisol levels up to two weeks post-behavior. This suggests an ongoing elevation of stress levels post-transfer, highlighting a longer-term impact of the social instability brought by such transfers.
Implications for Feral Horse Management
- The implications of this research are important for the management of feral horse populations. For example, on Shackleford Banks, it was observed that mares contracepted with porcine zona pellucida (PZP) made approximately ten times as many group changes as their untreated counterparts.
- Such behaviors, causing increased transfers and associated elevated cortisol levels, may increase these animals’ risks of chronic stress.
- As such, these findings underscore the need for management strategies to take into account behavioral and physiological impacts in order to maintain healthy, functional populations of such feral horses.
Cite This Article
APA
Nuñez CM, Adelman JS, Smith J, Gesquiere LR, Rubenstein DI.
(2013).
Linking social environment and stress physiology in feral mares (Equus caballus): group transfers elevate fecal cortisol levels.
Gen Comp Endocrinol, 196, 26-33.
https://doi.org/10.1016/j.ygcen.2013.11.012 Publication
Researcher Affiliations
- Department of Ecology and Evolutionary Biology, 106A Guyot Hall, Princeton University, Princeton, NJ 08544, USA; Department of Biological Sciences, 2119 Derring Hall (4020A), Virginia Polytechnic and State University, Blacksburg, VA, 24061, USA. Electronic address: nunezcmv@vt.edu.
- Department of Biological Sciences, 2119 Derring Hall (4020A), Virginia Polytechnic and State University, Blacksburg, VA, 24061, USA. Electronic address: adelmanj@vt.edu.
- Department of Ecology and Evolutionary Biology, 106A Guyot Hall, Princeton University, Princeton, NJ 08544, USA. Electronic address: jlstwo@gmail.com.
- Department of Ecology and Evolutionary Biology, 106A Guyot Hall, Princeton University, Princeton, NJ 08544, USA. Electronic address: lgesquie@princeton.edu.
- Department of Ecology and Evolutionary Biology, 106A Guyot Hall, Princeton University, Princeton, NJ 08544, USA. Electronic address: dir@princeton.edu.
MeSH Terms
- Aggression
- Animals
- Behavior, Animal
- Feces / chemistry
- Female
- Horses / physiology
- Hydrocortisone / metabolism
- Male
- Social Environment
- Stress, Physiological / physiology
- Swine
- Zona Pellucida / metabolism
Citations
This article has been cited 16 times.- Kern JM, Morris-Drake A, Radford AN. Behavioural, demographic and fitness consequences of social instability in cooperatively breeding dwarf mongoose groups. Proc Biol Sci 2023 Aug 30;290(2005):20230901.
- Medill SA, Janz DM, McLoughlin PD. Hair Cortisol Concentrations in Feral Horses and the Influence of Physiological and Social Factors. Animals (Basel) 2023 Jun 27;13(13).
- Vaziri GJ, Jones MM, Carr HA, Nuñez CMV. Out of the stable: Social disruption and concurrent shifts in the feral mare (Equus caballus) fecal microbiota. Ecol Evol 2023 May;13(5):e10079.
- Jones MM, Nuñez CMV. Laissez-Faire Stallions? Males' Fecal Cortisol Metabolite Concentrations Do Not Vary with Increased Female Turnover in Feral Horses (Equus caballus). Animals (Basel) 2023 Jan 3;13(1).
- Peterson EW, Segabinazzi LGTM, Gilbert RO, Bergfelt DR, French HM. Evaluation of Stress Accompanying Immunocontraceptive Vaccination in Donkeys. Animals (Basel) 2022 Feb 13;12(4).
- Shultz S, Britnell JA, Harvey N. Untapped potential of physiology, behaviour and immune markers to predict range dynamics and marginality. Ecol Evol 2021 Dec;11(23):16446-16461.
- Maldonado-Chaparro AA, Alarcón-Nieto G, Klarevas-Irby JA, Farine DR. Experimental disturbances reveal group-level costs of social instability. Proc Biol Sci 2018 Nov 14;285(1891).
- Seeber PA, Quintard B, Sicks F, Dehnhard M, Greenwood AD, Franz M. Environmental stressors may cause equine herpesvirus reactivation in captive Grévy's zebras (Equus grevyi). PeerJ 2018;6:e5422.
- Nuñez CMV, Adelman JS, Carr HA, Alvarez CM, Rubenstein DI. Lingering effects of contraception management on feral mare (Equus caballus) fertility and social behavior. Conserv Physiol 2017;5(1):cox018.
- Choi Y, Jung Y, Wickens CL, Yoon M. Effects of Social Interactions and Foundational Training on Behavior, Temperament, and Hormone Levels in Weanling Horses. Animals (Basel) 2026 Jan 4;16(1).
- Maldonado-Chaparro AA, Dougherty LR, Hayes LD, Ebensperger L. Social instability is associated with an elevated stress response but not with a fitness cost across vertebrate studies. R Soc Open Sci 2025 Jul;12(7):250691.
- Wang B, Duan W, Zhao J, Bai D. Detection of mare parturition through balanced multi-scale feature fusion based on improved Libra RCNN. PLoS One 2025;20(3):e0318498.
- Bhave A, Kieson E, Hafner A, Gloor PA. Identifying Novel Emotions and Wellbeing of Horses from Videos Through Unsupervised Learning. Sensors (Basel) 2025 Jan 31;25(3).
- Nuñez CMV, Adelman JS. Mean mares? Habitat features influence female aggression in response to social instability in the feral horse (Equus caballus). Biol Lett 2025 Jan;21(1):20240494.
- Hall C, Kay R. Living the good life? A systematic review of behavioural signs of affective state in the domestic horse (Equus caballus) and factors relating to quality of life. Part I: Fulfilment of species-specific needs. Anim Welf 2024;33:e40.
- Bazzano M, Marchegiani A, La Gualana F, Petriti B, Spaterna A, Laus F. Salivary analysis to unveil the paradigma of stress of domestic horses reared in the wild. Sci Rep 2024 May 17;14(1):11266.
Use Nutrition Calculator
Check if your horse's diet meets their nutrition requirements with our easy-to-use tool Check your horse's diet with our easy-to-use tool
Talk to a Nutritionist
Discuss your horse's feeding plan with our experts over a free phone consultation Discuss your horse's diet over a phone consultation
Submit Diet Evaluation
Get a customized feeding plan for your horse formulated by our equine nutritionists Get a custom feeding plan formulated by our nutritionists
