Physiological plasticity in elephants: highly dynamic glucocorticoids in African and Asian elephants

Fecal glucocorticoid metabolite and T3 profiles of orphaned elephants differ from non-orphaned elephants in Zambia

Background

Elephants provide valuable insight into how early-life adverse events (ELAEs) associate with animal health and welfare because they can live to advanced ages, display extensive cognitive and memory capabilities, and rely heavily on social bonds. Although it is known that African savanna elephants that experienced ELAEs, such as being orphaned due to human activities, have altered behavioral outcomes, little is known regarding the physiological consequences associated with those stressors.

Methods

We compared fecal glucocorticoid (fGCM) and thyroid (fT3) metabolites as well as body condition scores (BCS) in rescued and rehabilitated orphaned (early-dry season: n = 20; late-dry season: n = 21 elephants) African savanna elephants in Kafue National Park, Zambia to age- and sex-matched wild non-orphaned controls groups (early-dry season: n = 57; late-dry season: n = 22 elephants) during the early- (May/June) and late- (September/October) dry seasons, respectively. Age and sex were known for orphans. For non-orphan controls, age was estimated based on dung diameter, and sex was determined based on external genitalia. Hormone concentrations were compared between groups by age class to account for developmental and nutritional transitions experienced in early life. Given that environmental stressors (e.g., availability of food and water sources) change over the course of the dry season, early- and late-dry seasons were separated in the analyses.

Results

fGCM concentrations were higher in orphans at younger ages than non-orphaned controls of any age. This may be due to the younger orphans being temporally closer to the traumatic event and thus not having had sufficient time to establish meaningful social bonds that could buffer the negative outcomes associated with ELAEs. Alternatively, orphans could have acclimated to living under human care, resulting in fGCM concentrations that were not different from wild controls at older ages. Orphans also had significantly higher mean fT3 concentrations than non-orphans, suggesting increased caloric intake during rehabilitation. There was no difference in BCS between orphan and non-orphan elephants at any age or time period, possibly reflecting the limitations associated with BCS assessments in younger elephants.

Conclusions

Together, these results provide insight into possible physiological responses underlying ELAEs and/or living under human care, including alterations in fGCM and fT3 concentrations, particularly in younger orphans. While these hormonal changes suggest a physiological response to trauma, the support of social bonds and acclimation to human care may mitigate long-term stress effects, highlighting the critical role of social integration in elephant rehabilitation and conservation efforts.

Using Faecal Cortisol Metabolites to Assess Adrenocortical Activity in Wild-Living Alpine Marmot Marmota marmota: A Biological Validation Experiment

Faecal cortisol/corticosterone metabolites (FCMs) have become increasingly popular as an easy-to-sample, non-invasive and feedback-free alternative to assess glucocorticoid (GC) levels, key components of the neuroendocrine stress response and other physiological processes. While FCMs can be a powerful aid, for instance, for gaining insights into ecological and evolutionary processes, as well as to assess animal welfare or impacts of anthropogenic stressors on wildlife populations, this method comes with specific challenges. Because GCs are heavily metabolised before excretion, it is critical to validate the enzyme immunoassays (EIAs) used to measure FCMs. Additionally, because species may differ in metabolite profiles, assay validation must be performed separately for each focal species. Despite this, the use of unvalidated assays remains widespread. We performed a biological validation experiment to test a set of EIAs to measure FCMs and adrenocortical activity in free-living Alpine marmots Marmot marmota. We capitalised on capture and handling as part of a relocation project of marmots under the assumption that capture, and handling represent a stressful event and tracked changes in FCM levels over the following 48 h. Faeces samples collected at capture were assumed to return baseline FCM levels. Of the three EIAs tested, only the 11-oxoetiocholanolone '72T' EIA detected an increase in FCM levels about 18 h after capture. This result paves the way for future studies using FCMs to investigate the adrenocortical activity in this species.

Do African Savanna Elephants (Loxodonta africana) Show Interspecific Social Long-Term Memory for Their Zoo Keepers?

"An elephant never forgets" is a popular phrase that refers not only to the elephant's extraordinary ability to remember migration routes but also to its pronounced social long-term memory (SLTM). Previous studies have shown intra- and interspecies SLTM performance, but the ability of elephants to have memories of individual humans has not yet been investigated. We tested this interspecific SLTM using auditory, olfactory, and visual stimuli, each from familiar and unfamiliar persons, in two African savanna elephant (Loxodonta africana) cows living in a zoo. The two-choice object tests revealed a higher interest in sensory stimuli from familiar keepers they had not seen for 13 years than in unfamiliar people. Statistically significant differences were found for olfactory stimuli. In addition, there was significantly more interest in visual stimuli from current keepers than in stimuli from unfamiliar people. Contrary to the results of a previous study with elephants, this was not observed for olfactory stimuli. Due to the small sample size and magnitude of the influencing factors, that is, outdoor experiment, only spatial separation of the animals, these results only represent indications of the possible interspecific SLTM. Nevertheless, we were able to provide the first empirical evidence that L. africana stores information about specific people over a long period of time. Further studies with larger sample sizes, cross-modal testing, and people disliked by the elephants could provide more insights.

Development of a welfare assessment tool for tourist camp elephants in Asia

Background

Approximately one-third of Asian elephants are managed under human care, participating in educational, cultural, religious, and tourist activities. Management conditions vary considerably among venues, raising questions about whether welfare needs are consistently being met, particularly for Asian tourist camp elephants. To evaluate the well-being of elephants engaged in tourist activities, an evidence-based tool is needed for routine assessments to identify potential welfare risks, aid in the development of better camp standards, and enable caretakers to address specific concerns. While many animal welfare tools exist, none have been designed to consider specific environments and management practices faced by elephants living and working in tourist camps.

Methods

Using direct observations and interviews, the Elephant Welfare Assessment Tool (EWAT) was developed for tourist camp elephants using the Five Domains Model as a framework. Measures were selected based on peer-reviewed literature, existing standards and guidelines, and opinions from animal welfare experts working with zoo and tourist camp elephants. The EWAT differs from existing tools by including criteria on work activities and restraint methods (e.g., chaining and ankus use), factors common in Asia but not often encountered by western zoo elephants. Measures were scored using a 0-2 Likert Scale. The tool was tested in Thailand and determined by calculating a content validity index (CVI) and conducting inter-rater and test-retest reliability tests.

Results

The initial tool included 18 animal-based and 21 resource-based measures across four domains: Nutrition (n = 5), Environment (n = 14), Health (n = 10), and Behavior and Mental State (n = 10). Index scores of content validity (CVI) (Item CVI (0.83), Scale CVI/Average (0.98), and Scale CVI/Universal (0.89)) were high. Measures scoring less than 0.83 were removed: the opportunity to mate, the mahout-elephant relationship, and mahout job satisfaction. The final tool consisted of 42 questions related to 36 measures, including 18 animal-based and 18 resource-based measures within the Nutrition (n = 5), Environment (n = 11), Health (n = 10), and Behavior and Mental State (n = 10) domains. Intraclass correlation coefficients (ICC) for inter-rater reliability (0.78-0.90, p < 0.05) and test-retest (0.77-0.91, p < 0.05) analyses conducted at two camps showed good agreement.

Conclusions

This new assessment tool (EWAT) is a context-specific, holistic method designed to offer a practical means of conducting individual and institutional-level assessments of elephant welfare in tourist camps. It is based on the Five Domains Model using reliable and validated animal- and resource-based measures, data collection through direct observation and interviews, and a numerical scoring system. The tool includes several criteria applicable to tourist rather than zoo venues to make it more relevant to the challenges faced by working elephants in Asia.

Physiological changes in captive elephants in northern Thailand as a result of the COVID-19 tourism ban-stress biomarkers

The international travel ban instituted by the Thai government in March 2020 in response to the COVID-19 pandemic greatly affected how tourist camp elephants were managed, with reductions in exercise opportunities, longer chaining hours, and diminished food provisioning. This study was conducted to determine how those changes affected health and welfare biomarkers in individual elephants over the 2 years of the countrywide lockdown (April 2020-April 2022). Blood and fecal samples were collected from 58 elephants at six camps (monthly in Year 1, quarterly in Year 2) and analyzed for stress biomarkers - fecal glucocorticoid metabolites (fGCM), serum oxidative stress [malondialdehyde (MDA) and 8-hydroxy-2'-deoxyguanosine (8-OHdG)], and stress leukograms. Overall, fGCM concentrations increased within the first few months and remained higher than pre-COVID levels, as did the H/L ratio, a measure affected by cortisol. Serum 8-OHdG, an indicator of DNA oxidative damage, also increased over time, while monocytosis and lymphopenia further suggested alterations in immune function as a result of stress. By contrast, another marker of oxidative stress, serum MDA, declined, possibly in response to reduced roughage and supplement intake. A notable finding was a seasonal pattern of fGCM that was significantly different from previous studies. Whereas higher fGCM during the rainy season were observed in this study, previously, concentrations were highest during the winter, high tourist season. Thus, ironically, both the presence and absence of tourists have been associated with increased fGCM concentrations, albeit for different reasons. Camp management factors negatively affecting stress outcomes included shorter chain lengths, longer chain hours, lack of exercise, and reduced roughage and supplements. Overall, it was clear that camps struggled to maintain adequate care for elephants during the COVID-19 pandemic, highlighting the importance of tourist income and need for contingency plans to cope with potential future disruptions to tourism.