Survey of Factors Affecting Torpor in Lesser Hedgehog Tenrecs (Echinops telfairi)

Abstract

Lesser hedgehog tenrecs (Echinops telfairi) are small, nocturnal insectivores from Madagascar that exhibit hibernation and brief torpor bouts. While multiple studies have investigated torpor physiology, no studies have focused on torpor in tenrecs maintained under human care or their recommended husbandry. We surveyed 96 institutions (71.9% response rate) housing 172 tenrecs to assess husbandry, torpor, handling, and associated weight changes. Most institutions reported that torpor occurred annually, typically between October and April, and lasted approximately 5–6 months. Weight distributions differed significantly pre- versus post-torpor, with females and males losing 34.4 g and 20.9 g on average, respectively. Females were heavier than males before and after torpor, the first report of a sex-based weight difference in this species. Most institutions used tenrecs as ambassador animals, and approximately half continued educational programming during torpor. Tenrecs handled more frequently during torpor tended to gain more weight, likely due to increased energy expenditure and compensatory feeding. Tenrecs entered torpor regardless of daylight, temperature, or humidity, with no significant husbandry differences between torpor- and non-torpor-reporting institutions. Torpor is a critical physiological adaptation supporting energy conservation and species survival. Its expression should be supported through appropriate environmental conditions, diet, minimal disturbance, and monitoring.

1. Introduction

Lesser hedgehog tenrecs (Echinops telfairi) are small (110–230 g), nocturnal insectivores native to Western and Southwestern Madagascar [1]. They belong to the family Tenrecidae and are members of the superorder Afrotherians, mammals of African origin, also represented by the aardvark and African elephant [2,3,4]. They are one of 34 living species of tenrec, which are all found in Madagascar [5]. E. telfairi inhabit mostly dry deciduous and xeric spiny forests [1] and spend most of their time on the ground foraging or resting in tree hollows [6].

Tenrecs are known to enter torpor and hibernate in the wild, a physiologic adaptation known as heterothermy [7]. Generally, this occurs in the winter (May–September) in Madagascar [1]. Fluctuation in body temperature and decreases to near ambient temperatures result in a reduction in metabolic rate and conservation of energy and water [7]. Tenrec thermoregulation and metabolic physiology may be similar to those of early mammalian endotherms as they are known to exhibit low basal metabolic rates and highly variable body temperatures, often approximating ambient temperatures [4].

Short bouts of torpor may occur within a 24 h period with active phases, whereas hibernation may be prolonged (>24 h period) dormancy lasting months, typically with periodic arousals [4]. One laboratory-based study found that tenrecs entered short bouts of torpor in the summer and hibernation in the winter [7]. Another study under semi-natural conditions found that tenrecs entered short bouts of torpor in the winter (12–18 h each day) but not all exhibited hibernation [1]. Tenrecs likely developed heterothermy as an adaptation to the rapidly changing and unpredictable environments of Madagascar [4,8]. Heterothermy appears to be deeply integrated in their physiology, with evidence suggesting increased metabolic efficiency when exposed to fluctuating rather than stable temperatures [7].

Heterothermy may vary in wild and free-ranging animals. Multiple studies have investigated torpor physiology in tenrecs [1,7,9,10,11] but no literature currently focuses on torpor in tenrecs under human care or their recommended husbandry requirements (although the Lesser Hedgehog Tenrec Association of Zoos and Aquariums (AZA) Animal Care Manual is in preparation to assist with those topics). A study conducted in sugar gliders (Petaurus breviceps) found that animals under human care had a significant decrease in frequency and lengths of torpor as compared to free-ranging animals [12]. In the AZA Lesser Hedgehog Tenrec Species Survival Plan (SSP) population, not all individuals are reported to enter torpor yearly, and it is unknown whether some individuals experience true hibernation. The mechanisms underlying the absence of heterothermy in some individuals remain poorly understood.

This study aimed to discover the general husbandry and torpor cycles of lesser tenrecs housed in AZA institutions across the United States to see which factors (such as diet, temperature, humidity, and light cycles) do or do not affect it, the general frequency and length of torpor, animal handling during torpor, and its effects on body weight, behavior, reproduction, and health. This information will help improve our understanding of torpor in tenrecs housed under human care. The goal is that this information will help guide the development of general husbandry guidelines for tenrecs in torpor and strategies to promote and maintain this natural behavior under human care.

2. Materials and Methods

A total of 96 AZA facilities that house lesser hedgehog tenrecs were invited to participate in a survey regarding husbandry and torpor in their tenrecs. The survey consisted of 48 primary questions and a total of 97 questions (including optional, supplemental, and clarifying questions). It included multiple-choice (select one or multiple), short-answer, and follow-up questions if certain answer choices were selected (e.g., If “Other”, please specify). Because some questions allowed respondents to select multiple answers to account for differences in animal management within institutions, total percentages may exceed 100%. Respondents could select “Not applicable” if the question did not pertain to their tenrec(s).

Basic background questions included the name of the institution and contact information for the individual completing the survey. Husbandry questions pertained to housing, light cycle, temperature, and humidity for summer and winter seasons, general diet, and any changes in husbandry during torpor. Torpor questions assessed torpor frequency, duration, and variation among individuals, average weights of females and males prior to and after torpor, and use as ambassador animals. Specific questions addressed whether institutions encouraged their tenrecs to skip or avoid torpor. Additional questions focused on animal handling during torpor and any associated effects on behavior, reproduction, health status, or weight. Survey questions are included in Supplemental Document S1 and were developed based on the topics most frequently raised by institutions to the AZA Lesser Hedgehog Tenrec SSP, with questions regarding torpor representing the most common inquiry. Materials used to answer questions were not specified but are assumed to be based on observation, medical and animal care records.

The survey was created and results were collected using REDCap (Research Electronic Data Capture, Nashville, TN, USA), a secure, web-based software platform designed for building and managing data for research studies. Branching logic was utilized, which allowed for additional questions to be included if respondents selected specific answer choices. The survey was distributed via email communication. Data was collected in Microsoft Excel, and statistical analyses were performed with SPSS (Statistical Package for the Social Sciences) software version 28.

3. Results

The survey response rate was 71.9% (69/96) of institutions and included information pertaining to a total of 172 lesser hedgehog tenrecs (73 females, 86 males, and 13 unknown sex; 172/201 or 86% of total AZA population in 2025).

3.1. Husbandry

The vast majority of tenrecs were housed individually (67/68, 97.1%) with few male (1/68, 1.5%) and female pairs (8/68, 11.8%), breeding pairs (1/68, 1.5%), and dams housed with pups (2/68, 2.9%). Most tenrecs were housed in indoor enclosures in the summer (66/68, 97.1%) and winter months (68, 100.0%) with few given outdoor access during summer months (2/68, 2.9%).

For the summer and winter months, the most common daylight cycle, daylight source, and enclosure temperatures and humidities are displayed in

Table 1. Most common mean seasonal husbandry parameters for Echinops telfairi under human care.

Daylight Cycle	Summer Measurements	Winter Measurements
12 h	(30/69, 43.5%)	(23/69, 33.3%)
Enclosure temperature ranges
76–80 °F (24.4–26.7 °C)	38/68 (55.9%)	28/68 (41.2%)
71–75 °F (21.7–23.9 °C)	34/68 (50.0%)	43/68 (63.2%)
Enclosure humidity ranges
51–60%	27/68 (39.7%)	17/68 (25.0%)
41–50%	24/68 (35.3%)	26/68 (38.2%)
31–40%	—	19/68 (27.9%)

. In the summer, other common daylight cycles were 9 h (8/69, 11.6%) and 10 h (7/69, 10/1%) from the time lights are turned on to off. The daylight cycle did not change based on the season for the majority of institutions (48/69, 69.6%). Typical starting months for the summer light cycle were March (3/69, 4.3%), April (8/69, 11.6%), and May (4/69, 5.8%). Some tenrecs were housed near windows with a photoperiod dependent on the season and weather (4/69, 5.8%). Ambient room lighting was the most common daylight source in the summer (49/68, 72.1%) and winter (48/68 (70.6%). Other common daylight sources were artificial full spectrum lighting 45.6% (31/68), ambient window light 39.7% (27/68), and direct sunlight 2.9% (2/68).

The most common bulb types used were compact UVB and fluorescent bulbs including brands such as Reptisun (Zoo Med Laboratories, Inc., San Luis Obispo, CA, USA), Exo Terra (Rolf C. Hagen Corp., Mansfield, MA, USA), and Arcadia (Arcadia Reptile/Monkfield Nutrition Ltd., Cambridgeshire, UK). Heat/basking bulbs and T5 linear UVB bulbs were also common. In the winter, other common daylight cycles were 8 h (13/69, 18.8%) and 9 h (11/69, 15.9%). Similar to the summer, most institutions (47/69, 68.1%) did not change the daylight cycle based on season. Typical starting months for the winter daylight cycle were October (5/69, 7.2%) and November (11/69, 15.9%). The type of lighting used was similar to summer months.

Most institutions fed insects (67/68, 98.5%), commercial insectivore diets (66/68, 97.1%), and produce including leafy greens, vegetables, and fruit (52/68, 76.5%). In addition, 14.7% (10/68) of institutions offered commercial domestic dog and cat diets, eggs, and meat-based baby food. Insect gut-loading was reported by 59.1% (39/66) of institutions. Approximately half of the institutions provided all diet items daily and half provided it on a rotational basis.

3.2. Torpor

When asked if the amount or type of diet was altered during torpor, 50.7% (35/69) of institutions reported that it was not, 37.7% (26/69) reported that it was, and 11.6% (8/69) reported that it was not applicable (torpor was not observed in their tenrec(s)). Of those that altered diets, most (42.3%, 11/26) provided a lower amount of the total diet with unchanged proportions. Most institutions (73.9%, 51/69) did not change enclosure temperatures, humidity, light cycles, or environment prior to or during torpor. Of those that did make environmental changes during torpor (14.5%,10/69), approximately half shortened the daylight cycle, two increased the temperature by providing heat lamps or heat pads, and one facility lowered the temperature.

Tenrecs were reported to enter torpor regularly at 63.8% (44/69) of institutions. Among institutions where tenrecs did not consistently enter torpor, 15.9% (11/69) reported occasional torpor in all individuals, 8.7% (6/69) reported regular torpor in some individuals, 2.9% (2/69) reported no torpor, and 8.7% (6/69) reported torpor as an unknown occurrence due to lack of observation. Most tenrecs (69.6%, 48/69) experienced torpor once a year and few (4.3–11.6%, 3–8/69) went into and out of torpor multiple times a year. The average length of torpor was 5–6 months (47.8%, 33/69), followed by 3–4 months (21.7%, 15/69), 1–2 months (10.1%, 7/69), and 2–3 months (7.2%, 5/69). On average, torpor most commonly started in October (32.4%, 22/69) and November (47%, 32/68) and ended in March (48.5%, 33/68) and April (30.9%, 21/68). When asked about torpor pattern variation, four institutions noted that their females tended to enter torpor earlier than their males, three facilities noted that females tended to enter longer and deeper torpors, and two facilities noted that their females entered torpor but males did not.

Torpor was most commonly detected via visual inspection of behavior (94.1%, 64/68) and feeding logs (80.9%, 55.68). Clinical signs associated with torpor included decreased food intake (97.1%, 66/68), prolonged inactivity (83.8%, 57/68), decreased urine/fecal production (73.5%, 50/68), decreased responsiveness (69.1%, 47/68), and reduced body temperature (10.3%, 7/68). Of institutions with breeding pairs, 85.7% separated them during torpor. Of institutions with non-breeding pairs, 47.1% separated them during torpor.

Mean body weights of female and male tenrecs before and after torpor, along with average weight loss, are presented in

Table 2. The mean weight of Echinops telfairi females and males before and after torpor with standard deviation. The mean weight loss is also included in grams.

Sex	Weight Before Torpor (g)	Weight After Torpor (g)	Weight Loss (g)
Female	181.9 +/− 33.8	147.5 +/− 33.5	34.4
Male	156.2 +/− 33.7	135.3 +/− 22.3	20.9

. Overall, weight distributions differed significantly before and after torpor for females, males, and the overall population (Independent-Samples Mann–Whitney U test, all were p < 0.001). Body weights differed significantly between females and males both before torpor (Independent-Samples Mann–Whitney U test, p = 0.002) and after torpor (Independent-Samples Mann–Whitney U test, p = 0.034).

Institutions were asked whether any attempts were made to encourage tenrecs to skip torpor, meaning the animals were kept active rather than allowed to enter a torpid state. Most institutions (89.9%, 62/69) reported that they did not, while 10.1% (7/69) reported attempting to do so. Skipping torpor was encouraged by providing supplemental heat (71.4%, 5/7), increased light cycle (28.6%, 2/7), additional food (14.3%, 1/7), and additional handling (14.3%, 1/7). The most common reasoning for skipping torpor was to use the tenrec(s) for educational purposes (85.7%, 6/7). Even when tenrecs were encouraged to skip torpor, 71.4% (5/7) of tenrecs still entered torpor.

The vast majority of institutions (95.7%, 66/69) use their tenrecs as ambassador animals. An animal is considered an ambassador animal when it is presented to visitors and leaves its primary enclosure, or it is presented inside or outside its enclosure with the intent for visitors to have direct contact (e.g., feeding, touching). Approximately half (53.8%, 35/65) of the institutions used their ambassador tenrecs for educational programming (i.e., structured activities designed to teach visitors about the animals) during torpor. Ambassador animals were typically used weekly (40%, 14/35), biweekly (25.7%, 9/35), and monthly (14.3%, 5/35) during torpor.

Most institutions (57.1%, 20/35) did not have a protocol for when not to use ambassador animals during torpor, and 42.9% (15/35) of institutions had a set protocol. Described protocols included not using an animal for programming if the individual did not wake up, the animal was unwilling to uncurl, the animal did not interact with or respond to staff, or the animal did not voluntarily move out of the enclosure and into a transfer carrier. Behavior differences were commonly noted in ambassador tenrecs handled during torpor and included lower energy/activity levels, less food motivation, lower likelihood to explore surroundings, and increased likelihood to sleep during programming. No institutions reported any negative health effects when ambassador animals were handled during torpor.

Of the surveyed institutions, 30.4% (21/69) reported handling exhibit tenrecs during torpor, while 23.3% (16/69) did not. Exhibit animals were typically handled weekly (38.1%, 8/21), monthly (19%, 4/21), biweekly (14.3%, 3/21), and daily (14.3%, 3/21). Tenrecs handled daily or weekly during torpor exhibited greater weight gain than those handled less frequently; however, this difference was not statistically significant. As with ambassador animals, behavior differences were commonly noted in exhibit tenrecs handled during torpor and are similar to the aforementioned behaviors. Several institutions reported individuals who tended to be more irritable (hissing) when handled during torpor. No institutions reported any negative health effects when exhibit animals were handled during torpor.

Institutions reporting unknown or absent torpor (n = 8) did not demonstrate significant differences in handling or husbandry variables compared with institutions reporting torpor partially due to small sample size. Diet composition, housing, and environmental parameters largely overlapped between groups. Of torpor-reporting institutions, diet consisted of 97% commercial insectivore, 0% commercial omnivore, 97% insects, 75% produce, and 16% other. In comparison, non-torpor-reporting institutions reported that diet consisted of 88% commercial insectivore, 13% commercial omnivore, 100% insects, 75% produce, and 13% other. Methods of torpor detection slightly varied between torpor-reporting (2% body temp monitoring, 44% motion/activity logs, 79% feeding logs, 41% fecal/cleaning logs, 95% visual inspection of behavior) and non-torpor-reporting institutions (63% motion/activity logs, 88% feeding logs, 63% fecal/cleaning logs, 75% visual inspection of behavior). Additional distinctions are included in

Table 3. Most common mean seasonal husbandry parameters, use of Echinops telfairi as ambassador animals, reports of attempts to skip torpor, and reasoning for attempts to skip torpor in torpor-reporting and non-torpor-reporting institutions.

Husbandry Categories	Torpor-Reporting Institutions (n = 61)	Non-Torpor-Reporting Institutions (n = 8)
Summer daylight cycle (hours with standard deviation)	11.23 +/− 1.99	11.88 +/− 1.36
Summer enclosure temperature (°F)	71–75 (51%), 76–80 (52%)	71–75 (38%), 76–80 (75%)
Summer enclosure humidity (%)	41–50% (28%), 51–60% (39%)	41–50% (88%), 51–60% (38%)
Winter daylight cycle (hours with standard deviation)	10.13 +/− 1.93	10.88 +/− 1.25
Winter enclosure temperature (°F)	71–75 (66%), 76–80 (36%)	71–75 (38%), 76–80 (75%)
Winter enclosure humidity (%)	31–40 (31%), 51–60 (23%)	41–50 (63%), 51–60 (38%)
Use as ambassador animals	95%	100%
Reports of attempts to skip torpor	8%	25%
Reasoning for attempts to skip torpor	7% educational purposes	25% educational purposes

.

While the sample size limited meaningful comparisons between torpor-reporting (n = 61) and non-torpor-reporting (11.6%, n = 8) tenrec institutions, those reporting unknown or absent torpor were more likely to feed an omnivore diet (13% versus 0%), use tenrecs as ambassador animals (100% versus 95%), and encourage animals to skip torpor (25% versus 8%). However, in both groups, 13–16% of the diet consisted of other food items, most commonly eggs and meat-based products, so there is unlikely much difference in diet between groups.

4. Discussion

Most institutions reported that at least some tenrecs entered torpor regularly (88.4%, n = 61), which is consistent with a previous study in which 85% of tenrecs in North American zoos were reported to enter some form of torpor [13]. Some individuals may not enter torpor yearly, while others may not enter torpor at all. The inability to detect statistically significant differences between torpor-reporting and non-torpor-reporting institutions represents a limitation of this study and is likely related to the limited sample size of animals that did not undergo torpor or whose torpor status was unknown.

In the surveyed AZA SSP population, tenrecs entered torpor regardless of changes in light cycle, temperature, or humidity. This finding is consistent with results from another survey-based study of lesser hedgehog tenrecs housed in North American zoos [13]. In other animals, particularly temperate and arctic species, torpor is typically triggered by photoperiod, lower ambient temperatures, and decreased food availability [4]. In contrast, the factors influencing torpor in tropical species, such as tenrecs, appear to be more variable and may be less dependent on external environmental stimuli [4]. Nonetheless, lower and fluctuating ambient temperatures have been shown to result in lower metabolic rates, longer torpor bouts, and synchronized activity phases in lesser hedgehog tenrecs [7]. Photoperiod is also thought to influence torpor timing in heterotherms, although it is often correlated with concurrent changes in temperature and humidity [7].

Most tenrecs in the surveyed population experienced one yearly torpor season (69.6%, 48/69), but some individuals went into and out of torpor multiple times a year. Torpor has been documented to occur throughout the year outside of winter conditions in a laboratory-based study [7]. The variability in torpor patterns among individuals may reflect biological plasticity rather than a single cause. Animals that aroused more frequently may have been influenced by factors such as warmer exhibit microclimates or increased disturbance, whereas those that remained in prolonged torpor may have benefited from more suitable den or hide structures or better overall health. However, these possibilities could not be directly assessed in this study, as detailed measurements of microclimate, exhibit design, and individual health during torpor were not systematically collected.

A laboratory-based study investigated the effects of constant and fluctuating temperatures on torpor in E. telfairi and found that fluctuating ambient temperatures in summer conditions resulted in significantly longer torpor bouts, or length of torpor periods [7]. Therefore, individuals in the surveyed population that experienced one longer torpor period may have also experienced more temperature variation. Additionally, in the aforementioned study, animals housed at constant ambient temperatures throughout the year invested approximately twice as much energy through endogenous heat production as measured through minimum oxygen consumption [7]. Thus, it was deduced that fluctuating temperature conditions were more energetically efficient for E. telfairi [7].

Natural environmental conditions for lesser hedgehog tenrecs vary by region and season in Madagascar. Across Atsimo-Andrefana, Menabe, and Androy, average daylight ranges from 10.5 to 13.2 h, ambient temperatures range from 20 to 28 °C (68–82.4 °F), and relative humidity ranges from 60 to 83% [14]. In managed settings, husbandry should aim to approximate natural conditions by maintaining environmental parameters within these ranges. The summer season in Madagascar, which occurs from November through April, is characterized by increased rainfall, higher temperatures, and increased humidity [14,15]. Accordingly, temperature and humidity may be increased during the boreal summer months to better reflect natural seasonal conditions. Institutions may also consider daily temperature and humidity fluctuations if feasible to promote torpor and energy efficiency in their animals [7].

In the wild, tenrecs generally enter short torpor bouts [1] or bouts of hibernation [7] during the austral winter, typically between May to September. In contrast, in the surveyed AZA SSP population, torpor was generally observed during the boreal winter, from October to April with a mean duration of 5–6 months followed by 3–4 months. This duration is longer than previously reported for tenrecs in North American zoos, where 75% of institutions reported 2–4 months of torpor and 17% reported 1–2 months [13]. Previous studies have characterized the duration of torpor bouts (12–18 h) [1] and reported that animals may hibernate for several months [7] but the overall duration of torpor in the wild has not been quantified to our knowledge. Overall, the seasonal timing of torpor in North American populations appears to mirror that of wild populations, with a shift in hemisphere (October–April versus May–September). As true hibernation has not been documented in the AZA SSP population, survey questions were focused on torpor.

A 2021 survey-based study of lesser hedgehog tenrecs in North American zoos reported that most institutions offered a commercial insectivore diet (85%, 11/13), insects (92%, 12/13), and produce (69%, 9/13) [16]. Similar feeding patterns were observed in the present study, with insects, commercial insectivore diets, and produce commonly included, suggesting consistency in feeding practices across institutions and over recent years. In contrast, a 2017 survey-based study identified cat food (52%) and insects (52%) as the most offered diet items [13]. Together, these findings suggest a shift toward feeding practices more closely aligned with the species’ natural diet, reflecting improvements in husbandry standards and greater availability of commercial insectivore-based diets. This shift may have positive implications for animal health by better supporting species-appropriate nutritional needs, though institutional variation persists.

Free-ranging lesser hedgehog tenrecs consume mostly insects including termites, crickets, insect larvae, centipedes, and millipedes [5,17]. Tenrecs are also considered omnivorous and will opportunistically consume small vertebrates such as reptiles [17], amphibians, birds, and small mammals [5] although data is limited. Their natural diet may also differ depending on the region and season [17]. A predominantly insectivorous diet is recommended for tenrecs under human care, consisting of an insectivorous commercial diet, gut-loaded insects offered on a rotational basis, and supplemented with appropriate produce. Omnivorous commercial dog or cat diets and other meat-based diets are not recommended as there are no studies confirming avian or mammal remains in the stomach contents of E. telfairi.

During the winter, food intake is markedly reduced with some studies showing that most lesser hedgehog tenrecs do not eat; thus, animals in torpor or hibernation may lose around 30 g [7] or up to 25% body mass [1]. In the surveyed population, females lost an average of 34.4 g (approximately 19% body mass) and males 20.9 g (approximately 13% body mass), consistent with previous reports from semi-natural and laboratory conditions known as the Dehnel effect, endogenously controlled reduction in mass during the winter [1,7]. A balanced diet should continue to be offered during torpor; however, weight loss is expected regardless of the amount provided. It is reasonable to reduce total dietary intake during torpor and to monitor body weight periodically (e.g., biweekly to monthly) to ensure that body mass loss does not exceed 20–25%. The amount of diet offered and consumed, along with fecal output and activity levels, should be monitored to help identify when torpor is ending and when increased diet quantity may be required. To our knowledge, this is the first study to identify a statistically significant difference in body weight between female and male lesser hedgehog tenrecs, with females being significantly heavier. These differences should be kept in mind when monitoring weight trends in this species.

Despite widespread use of tenrecs as ambassador animals, many institutions continued programming during torpor without established guidelines for discontinuing ambassador activities. If programming occurs during periods of activity and animals voluntarily participate (e.g., willingly entering a transport carrier), continued use for educational purposes can be continued as no negative health effects associated with handling during torpor were reported. However, development of formal protocols for ambassador use during torpor is recommended, including close monitoring of animal behavior and body weight. Animals should be excluded from programming if they are actively dormant, clinical signs of stress are observed, participation is decreased, or body weight loss exceeds 25%. Participation in programming can be resumed pending reassessment or after the torpor season.

Handling during torpor may be necessary for essential husbandry procedures, including body weight monitoring; however, non-essential handling during torpor should be minimized when possible, due to the associated energetic costs of induced arousal. Arousals during hibernation are energetically demanding and have been associated with increased production of reactive oxygen species, cellular damage [4], and depletion of fat stores [18]. In hibernating brown bears (Ursus arctos), capture-induced arousal resulted in prolonged physiologic disruption, with body temperature and heart rate requiring 2–3 weeks to return to baseline, suggesting an increased metabolic demand [18]. In bats, increased frequency of arousals during hibernation has been associated with reduced overwinter survival, with body mass loss correlating with the number of arousals [18]. Additionally, mortality associated with White-nose syndrome (WNS) in free-ranging little brown bats (Myotis lucifugus) is thought to be partially attributable to alterations in torpor bout dynamics [19]. While physiologic arousals are considered an important component of normal hibernation in some species [4], human-induced arousals should be avoided whenever feasible. Interestingly, some tropical species, including tenrecs and lemurs, can undergo hibernation without periodic physiologic arousals, resulting in increased energy conservation [4,20], further supporting efforts to minimize disturbance during torpor in tenrecs.

In contrast to reports in bats, our data, although not statistically significant, suggest that tenrecs handled more frequently during torpor tended to gain more weight than those handled less often. This likely reflects increased torpor disturbances, which consequently elevate energy expenditure, as reported in free-ranging animals. Unlike in wild conditions, however, tenrecs under human care have readily available food when aroused, which may lead to increased consumption and contribute to weight gain. Minimizing normal, physiologic weight loss in animals disturbed during torpor could also predispose them to obesity-related conditions, as these individuals may gain more weight over their lifetime compared with animals experiencing fewer disturbances. This is particularly relevant given that hepatic lipidosis accounted for 11% of deaths in a survey of North American tenrecs under human care [13].

Overall, limited information exists on natural torpor behavior in tenrecs, making direct comparisons between individuals in zoological institutions and their wild counterparts challenging. The variability in torpor expression observed in this study, despite relatively stable captive conditions, raises questions about the evolutionary role of torpor in tenrecs. Such flexibility may represent an adaptive strategy to cope with unpredictable food availability or fluctuating environmental conditions in the wild, suggesting that diverse torpor patterns are likely a fundamental aspect of their biology rather than solely environmentally driven. In zoological settings, fewer individuals may enter torpor due to routine husbandry, regular monitoring, and consistent food provision, which could reduce the need for prolonged energy conservation strategies. Nevertheless, the fact that most tenrecs still entered torpor despite preferred environmental conditions and readily available food supports the idea that heterothermy is a deeply conserved physiological trait.

Because torpor is a key physiological adaptation in tenrecs and has been linked to increased survival and potentially enhanced longevity, it should not be actively discouraged under human care. Evidence across heterothermic mammals indicates that torpor and hibernation are associated with improved winter survival, slowed physiological aging, and reduced telomere shortening during periods of low body temperature [20]. In strepsirrhine primates, greater expression of torpor has similarly been associated with increased lifespan, further supporting the potential adaptive and longevity-related benefits of this physiological state [20]. A similar relationship between torpor and lifespan has also been described in Turkish hamsters [20]. Furthermore, heterothermy may promote species survival in an ever-changing environment and climate, as torpor reduces energy demands and foraging requirements [20]. Although tenrecs under human care do not experience the same environmental pressures as free-ranging conspecifics, SSP goals include supporting behaviors that reflect normal, physiologically adaptive processes associated with species survival.

5. Conclusions

Most lesser hedgehog tenrecs in the AZA SSP population enter torpor regularly, though individual variation exists. Torpor in managed tenrecs appears largely independent of photoperiod, temperature, or humidity, suggesting that environmental parameters do not need to be modified to accommodate torpor. However, husbandry practices that approximate natural seasonal conditions and allow for temperature and humidity fluctuations may support longer, more energetically efficient torpor bouts. Weight loss during torpor is expected, but periodic monitoring is encouraged to ensure weight loss does not exceed 20–25% of body weight, keeping in mind sex-specific differences.

While tenrecs are frequently used as ambassador animals, non-essential handling during torpor should be minimized, and formal protocols with clear exclusion criteria are recommended. Torpor represents a key physiological adaptation associated with energy conservation and potentially increased longevity and should not be actively discouraged. Furthermore, institutions should prioritize management practices that allow animals to express normal, innate behaviors and promote long-term survival in managed care whenever possible.

A limitation of this study is the inability to assess all factors that may influence torpor. Future research should investigate the potential effects of age, exhibit size, cohabitation, and detailed aspects of ambassador use, including the type of programming and level of physical contact with the public. Other limitations of this study are that materials used to answer questions were not specified and responses were based largely on observational and self-reported data rather than direct physiological measurements; therefore, results may be influenced by respondent interpretation, recall accuracy, and reporting bias. Furthermore, commonly used terms were not always described in survey questions (e.g., feeding logs); therefore, differences in question interpretation may have also contributed to respondent bias.

Institutions are encouraged to monitor body weight and document behavior in association with torpor, including clinical signs of stress (balling up, hissing, trembling), hiding, decreased activity, and lack of participation in programming. Future studies using serial fecal glucocorticoid measurements, as previously reported in laboratory rodents to assess stress [21], could also serve as an objective measure of physiological responses and the effects of torpor in tenrecs across institutions. Future prospective studies that incorporate ecological context and broader physiological comparisons between tenrecs under human care and their wild counterparts could further strengthen evidence-based management. Furthermore, the use of ZooMonitor (Wildbytes Technologies, Cambridge, UK), a web-based platform for systematic behavioral observations, could provide standardized, quantitative data across institutions, enhancing our understanding of tenrec behavior and torpor and expanding upon the findings presented here.