Environmental Enrichment Effect on Fecal Glucocorticoid Metabolites and Captive Maned Wolf (Chrysocyon brachyurus) Behavior

Environmental enrichment is a technique that may reduce the stress of nonhuman animals in captivity. Stress may interfere with normal behavioral expression and affect cognitive decision making. Noninvasive hormonal studies can provide important information about the stress statuses of animals. This study evaluated the effectiveness of different environmental enrichment treatments in the diminution of fecal glucocorticoid metabolites (stress indicators) of three captive maned wolves (Chrysocyon brachyurus). Correlations of the fecal glucocorticoid metabolite levels with expressed behaviors were also determined. Results showed that environmental enrichment reduced fecal glucocorticoid metabolite levels. Furthermore, interspecific and foraging enrichment items were most effective in reducing stress in two of the three wolves. No definite pattern was found between behavioral and physiological responses to stress. In conclusion, these behavioral and physiological data showed that maned wolves responded positively from an animal well being perspective to the enrichment items presented.     

Behavioral responses of maned wolves (Chrysocyon brachyurus, Canidae) to different categories of environmental enrichment stimuli and their implications for successful reintroduction

The maned wolf (Chrysocyon brachyurus, Illiger, 1815, Canidae) is a threatened species that inhabits the cerrados of Brazil, Argentina, Peru, Bolivia, Paraguay, and Uruguay. Captive maned wolves could be potentially used in reintroduction programs for species conservation; however, it is necessary that their behavior and cognitive abilities are conserved. Environmental enrichment is a tool used to stimulate captive animals and maintain a natural behavioral repertoire. To compare the variation of captive maned wolves' behavioral responses to environmental enrichment, we studied three maned wolves held by Belo Horizonte Zoo, Brazil. Foraging, interspecific, and intraspecific stimuli were offered to the animals and their responses were compared with a baseline and postenrichment treatments. The test was used to help in choosing which one of the three individuals would participate in a reintroduction project. The results showed that stimuli type did influence the animal's responses, and that individually wolves responded differently to foraging, interspecific, and intraspecific enrichment items (P80.05 for some behaviors in each enrichment category). The individual's personality seemed to influence their behavioral responses, with animals showing bold and shy responses, and this trait should be considered during decision makings for reintroduction.     

Noninvasive assessment of adrenal activity associated with husbandry and behavioral factors in the North American clouded leopard population

The North American clouded leopard (Neofelis nebulosa) population is far from self‐sustaining. Breeding success is poor and behavioral problems (i.e., fur‐plucking, tail‐chewing, excessive hiding or pacing, and intersexual aggression that results in mate killing) are common. This study was undertaken to investigate whether some of these problems may be indicators of chronic stress (as reflected by persistently elevated glucocorticoid levels) and whether they are associated with specific management factors. A fecal corticoid metabolite assay was validated to monitor adrenal activity in clouded leopards. Adrenocorticotropic hormone (ACTH) challenges conducted in four clouded leopards established the biological relevance of the assay system. Fecal corticoid concentrations increased 14‐fold above baseline within 24 hours after ACTH administration. Adrenal activity then was monitored in 72 (36 males; 36 females) clouded leopards (65% of the North American Species Survival Plan population) during a 6‐week period and compared to husbandry and behavior data. There was a significant (P < 0.01) gender difference in fecal corticoid concentrations, with females producing higher concentrations than males. Multiple regression analyses revealed negative associations (P < 0.01) between enclosure height, number of hours keepers spent with each animal per week, and corticoid concentrations. A positive correlation (P < 0.001) was found between the number of keepers caring for an individual and corticoid concentrations. Higher fecal corticoid concentrations (P ≤ 0.05) were measured in clouded leopards kept on public display or near potential predators compared to individuals maintained off exhibit or in the absence of predators. Individuals that performed self‐injuring behaviors also had elevated fecal corticoids (P < 0.01). Spearman‐rank correlation analysis of keeper ratings and hormone data revealed positive associations (P ≤ 0.05) between some behaviors (pace, sleep, hide, and fearful/tense) and fecal corticoid concentrations. Overall these results indicate that noninvasive fecal corticoid monitoring has enormous potential for investigating how management and behavioral problems are related to animal well‐being. If conducted under carefully controlled experimental paradigms, this technique could allow researchers and managers to identify problem areas of captive management for clouded leopards (e.g., enclosure height, keeper time) and evaluate the efficacy of strategies designed to promote animal welfare and increased reproductive success. Zoo Biol 21:77–98, 2002. © 2002 Wiley‐Liss, Inc.     

Transit time and digestibility of two experimental diets in the maned wolf (Chrysocyon brachyurus) and domestic dog (Canis lupus)

Recent research involving nutritional management of clinical disease secondary to cystinuria in captive maned wolves (Chrysocyon brachyurus) in the United States resulted in the production of a commercially manufactured maintenance diet and subsequently, a further modified experimental diet. These two diets differed only in their protein sources and sodium concentrations. The purpose of this study was to further investigate these diets by determining their digestibility and transit time in maned wolves, and also to compare these results to the digestibility and transit time of the diets in domestic dogs. The experiment consisted of two diets (maned wolf commercial maintenance diet and experimental diet) and two species (maned wolf and domestic dog [beagle]) arranged as a 2 × 2 factorial design. For the transit time study, titanium dioxide (TiO₂, 5 g/kg diet) was administered as a pulse dose and total collection of feces was carried out for 50 hr. There was no effect of diet or species on initial Ti recovery time (IRT), the amount of Ti recovered at IRT, or the time to reach 50% of Ti excretion in the feces. Maned wolves had lower total percent recovery (P<0.01) of Ti than dogs and shorter time to last recovery of Ti in the feces (P<0.05), however, marker excretion in the maned wolves may not have been complete. For the digestibility study, in which chromic oxide was used as a marker, fecal samples were collected on 2 consecutive days immediately after 12 days of being fed the diets and then analyzed for dry matter, energy, protein, and minerals. Crude protein, calcium, phosphorus, and zinc apparent digestibilities were unaffected by species or diet (P>0.05). Apparent digestibility of dry matter (P<0.05) and energy (P<0.01) were higher in the experimental diet and in the dogs. Both dogs and maned wolves fed the maintenance diet exhibited a greater apparent retention of copper, iron, and magnesium (P<0.01). Dogs had a higher apparent retention of magnesium and sodium than the maned wolves. Zoo Biol 0:1–13, 2006. © 2006 Wiley‐Liss, Inc.     

Environmental enrichment of brown capuchins (Cebus apella): Behavioral and plasma and fecal cortisol measures of effectiveness

No consensus exists about the quantity and variety of environmental enrichment needed to achieve an acceptable level of psychological well‐being among singly housed primates. Behavioral and plasma and fecal cortisol measures were used to evaluate the effectiveness of four levels of toy and foraging enrichment provided to eight wild‐caught, singly housed adult male brown capuchins (Cebus apella). The 16‐week‐long study comprised six conditions and began with a 4‐week‐long preexperimental and ended with a 4‐week‐long postexperimental period during which the subjects were maintained at baseline enrichment levels. During the intervening 8 weeks, the subjects were randomly assigned to a sequence of four 2‐week‐long experimental conditions: control (baseline conditions), toy (the addition of two plastic toys to each cage), box (access to a foraging box with food treats hidden within crushed alfalfa), and box & toy (the addition of two plastic toys and access to a foraging box). Behavioral responses to changes in enrichment were rapid and extensive. Within‐subject repeated‐measure ANOVAs with planned post hoc contrasts identified highly significant reductions in abnormal and undesirable behaviors (and increases in normal behaviors) as the level of enrichment increased from control to toy to box to box & toy. No significant behavioral differences were found between the control and pre‐ and postexperimental conditions. Plasma and fecal cortisol measures revealed a different response to changing enrichment levels. Repeated‐measure ANOVA models found significant changes in both these measures across the six conditions. The planned post hoc analyses, however, while finding dramatic increases in cortisol titers in both the pre‐ and postexperimental conditions relative to the control condition, did not distinguish cortisol responses among the four enrichment levels. Linear regressions among weekly group means in behavioral and cortisol measures (n = 16) found that plasma cortisol was significantly predicted by the proportions of both normal and abnormal behaviors; as the proportion of normal behaviors increased, the plasma cortisol measures decreased. Plasma cortisol weekly group means were also significantly and positively predicted by fecal cortisol weekly group means, but no behavioral measure significantly predicted fecal cortisol weekly group means. In sum, these findings argue strongly that access to a variety of toy and foraging enrichment positively affects behavioral and physiological responses to stress and enhances psychological well‐being in singly housed brown capuchins. Am. J. Primatol. 48:49–68, 1999. © 1999 Wiley‐Liss, Inc.     

Behavioral changes associated with introductions of male maned wolves (Chrysocyon brachyurus) to females with pups

Three male maned wolves were successfully introduced to their mates and 7‐ to 12‐week‐old pups at the Houston Zoological Gardens and Fossil Rim Wildlife Center in 1994 and 1995. The introductions took 3–7 weeks and had three stages: 1) allowing the male to see the female and pups through a chain‐link panel or a full chain‐link fence, 2) introducing the male and female without the pups present, and 3) introducing the male to the pups. For 7 days before Stage 2 and 7 days during Stage 3, the adults were observed for 150 hr. The amount of time they spent active and the amount of time they spent near the pups were recorded, as well as all behaviors they directed to the pups. After the males were introduced, the females' activity decreased, and the males' activity increased. The females spent less time near the pups after the introduction. The introduction did not affect the females' rates of affiliative or aggressive behaviors to the pups, and there was no difference between males' and females' rates of affiliative or aggressive behaviors. This introduction procedure offers an alternative to leaving the male with the pups from the time they are born. The adults' behavioral changes after the introduction show the benefits that occur when captive male maned wolves are allowed to help rear their pups. Zoo Biol 18:189–197, 1999. © 1999 Wiley‐Liss, Inc.     

First observations of nest attendance behavior by wild maned wolves,Chrysocyon brachyurus

In many species of canids the male's role in reproduction extends to providing extensive or some parental care to his offspring. Maned wolves are a monogamous canid species whose males have been observed providing parental care to their offspring in captivity, but no field observations exist. We observed a wild pair of maned wolves at their nest site in a period soon after the female had given birth for a total period of 65 days. We made five observation sessions with an average of 3–4 days each separated by approximately 2 weeks. Direct visual observations of maned wolves were made each 30 min during the hours of darkness (17:00–07:00) using night-vision binoculars and confirmed by VHF radiotelemetry. During observations we recorded the location of the male and the female in relation to the nest (i.e., in the nest, nearby or long way from the nest). The results showed that the female spent more than 60.44% of her time in or near the nest. The male spent 28.90% of his time in or near the nest. There was a positive significant correlation between the female and the male in terms of the amount of time spent in or near the nest (P<0.01). The maned wolves showed a strong temporal variation in time spent in or near the nest. In conclusion, our data show that wild male maned wolves—probably—provide parental care through provision of food to their female and presumed offspring rather than “babysitting.” Zoo Biol 28:69–74, 2009. © 2008 Wiley-Liss, Inc.     

Use of behavioral measures to assess reproductive status in maned wolves (Chrysocyon brachyurus)

Captive breeding efforts of the threatened maned wolf (Chrysocyon brachyurus) have been plagued by a lack of reliable reproduction and a high rate of neonatal mortality. A particular problem for animal managers has been the ability to detect pregnancy in a noninvasive manner. Pseudopregnancies are common, and many staff hours are expended preparing for a birth that may not occur. The objectives of our study were to document changes in behavior during the breeding season in captive maned wolves in order to determine if behaviors other than sexual (i.e., copulation) could be used to distinguish nonbreeding from breeding pairs and, further, whether successful breeding pairs (young born) could be distinguished behaviorally from breeding pairs that did not produce young (pseudopregnant). Between 1988 and 1994, behavioral data were collected during the annual reproductive season from 52 maned wolf pairings (27 males, 26 females) housed at 17 North American institutions. Breeding animals showed significant increases in rates of affiliative behaviors (approach, friendly) and the amount of time spent in close association (social) during the estrous period, compared to pre- and post-estrous periods. In contrast, the behavior of nonbreeding pairs varied little throughout the breeding season. Discriminant function analysis (DFA) showed that several behavioral measurements during certain reproductive periods were useful in discriminating between nonbreeding and breeding animals (rates of friendly and social behavior for males, marking and social behavior for females). Unsuccessful (pseudopregnant) and successful breeding pairs could be further distinguished on the basis of agonistic and approach behavior frequencies (successful females showed higher rates of agonistic and lower rates of approach behavior during certain periods; successful males had higher rates of both behaviors). Discriminant equations for key behavioral measurements and examples of their practical application are presented. DFA provides animal managers with an effective, noninvasive technique for assessing the reproductive status of maned wolf pairs. © 1996 Wiley-Liss, Inc.     

Effect of housing and environmental enrichment on adrenocortical activity,behavior and reproductive cyclicity in the female tigrina (Leopardus tigrinus) and margay (Leopardus wiedii)

The objective of this study was to evaluate the effects of different captive housing conditions on reproductive cyclicity and adrenocortical activity in adult females of two small‐sized felid species, the tigrina (Leopardus tigrinus; n = 3) and margay (Leopardus wiedii; n = 2). Females were housed as singletons and subjected to three enclosure conditions over successive time periods: Phase I—large, enriched enclosures for 3 months; Phase II—small, empty enclosures for 5.5 months; Phase III—the same small enclosures enriched with branches and nest boxes for 6.5 months. Fecal samples were collected five times weekly throughout the study for analysis of progestagen, estrogen, and corticoid metabolites. On the basis of observed behaviors, stereotypic pacing was more frequent before feeding for all cats, regardless of enclosure conditions. Both species displayed a bimodal activity pattern, with peaks occurring at nightfall and dawn. All animals exhibited agitated behavior, characterized by a high frequency and duration of stereotypic pacing, primarily during the first 3 days after moving to the small empty enclosures. On the basis of hormonal analyses, ovarian follicular activity decreased and corticoid concentrations increased in tigrinas after transfer to the small barren cages compared to the patterns observed in the initial large, enriched enclosures. Corticoid concentrations in tigrinas then declined after small cage enrichment. Margay females exhibited increased corticoid excretion during Phases II and III, but in contrast to tigrinas, concentrations remained high even after cage enrichment. It was further showed that enriching the small enclosures was insufficient to reestablish normal ovarian activity within the time frame of the study for both species. In summary, margay and tigrina females exhibited distinct elevations in corticoid concentrations after transfer from large enriched enclosures to smaller barren cages that corresponded with agitated behavior, especially immediately after transfer. Fecal corticoid concentrations were reduced after cage enrichment in tigrinas, but not in margays. Although only a few individuals were evaluated, data suggest there may be species differences in response to captive environmental conditions. Overall results emphasize the importance of enclosure dimensions and enrichment when designing species appropriate environments for improving the health and reproductive fitness of threatened species. Zool Biol 26:441–460, 2007. © 2007 Wiley‐Liss, Inc.     

Taurine deficiency in maned wolves (Chrysocyon brachyurus) maintained on two diets manufactured for prevention of cystine urolithiasis

This study assesses the long‐term effects of an experimental diet vs. a commercially available manufactured diet, intended to reduce clinical disease related to cystinuria, on the taurine status of captive maned wolves. For 13 weeks, two pairs of maned wolves were maintained on the commercially available maintenance diet, whereas two individually housed wolves were maintained on the experimental diet. All six wolves, at the beginning and at the end of the diet trial, had severely decreased plasma concentrations of taurine (as compared to the normal canine reference range of 60–120 nmol/ml) (National Research Council [2003] National Academies Press) with average taurine concentrations of 16 nmol/ml at the beginning of the study and 3 nmol/ml at the end of the study. There was no statistically significant difference in the taurine concentrations between animals on the maintenance vs. experimental diets. Both diets were supplemented subsequently with taurine at a concentration of 0.3%. All study animals were eventually switched to the taurine‐supplemented version of the commercially manufactured maintenance diet and subsequent samplings were carried out to monitor plasma taurine concentrations. A final sampling, carried out approximately 5 months after the initiation of taurine supplementation, showed an average taurine concentration within the target canine reference range (90.25 nmol/ml). There are numerous physiologic (e.g., possible unique metabolism and requirements for taurine in this species as compared to other canids) and dietary factors (e.g., effects of the types and concentrations of fiber and protein on nutrient availability, taurine metabolism, and enterohepatic circulation of taurine‐conjugated bile salts; impaired taurine synthesis secondary to low cysteine availability) that could be potential contributors to the development of taurine deficiency in the maned wolves in this study. Taurine supplementation should be considered in maned wolves maintained on diets intended for reduction of cystinuria‐related complications. Zoo Biol 0:1–14, 2005. © 2005 Wiley‐Liss, Inc.     

A work‐for‐food enrichment program increases exploration and decreases stereotypies in four species of bears

Zoo‐housed bears are prone to exhibiting stereotypic behaviors, generally considered indicators of negative welfare. We explored the effects of a variable‐time feeding enrichment schedule on behavioral indicators of welfare in four bear species at Cleveland Metroparks Zoo. We distributed the diets of eight bears in one of five enrichment items, for two consecutive days each, and monitored behavior throughout the day. In Experiment 1, we compared variable‐time to fixed‐time presentation of enrichment over two, 10‐day periods. Overall, bears performed more exploratory behavior when enriched (p < 0.0001). Furthermore, variable‐time enrichment was associated with a greater increase in exploratory behavior than fixed‐time enrichment when compared to baseline (p < 0.001). Both fixed‐time (p_unadjusted <0.05, p_adjusted = 0.07) and variable‐schedule (p_unadjusted <0.05, p_adjusted = 0.09) enrichment were also associated with similar decreases in abnormal behavior compared to baseline. For Experiment 2, we tested habituation to enrichment over 30 days using multiple items and a semi‐variable presentation schedule. Again during the enrichment period, bears exhibited increased exploratory behavior (p < 0.0001) and decreased abnormal behaviors compared to baseline (p_unadjusted = 0.05, p_adjusted = 0.09). We observed no habituation during the 30‐day sustained enrichment period for these behaviors. Collectively, these results suggest that daily, variable‐schedule feeding enrichment, with intermittent presentation of unique enrichment items, increases behavioral indicators of positive welfare and decreases behavioral indicators of negative welfare.     

Feed intake and digestion in the maned wolf (Chrysocyon brachyurus): Consequences for dietary management

Captive maned wolves (Chrysocyon brachyurus) often consume diets high in prey and meat items even though they are omnivorous in the wild. These soft, high protein diets may exacerbate conditions of gingivitis and cystinuria in this species. Feed intakes were monitored in wolves provided with prey and meat-based diets (3 periods) and subsequently with extruded dog chows and small amounts of prey (2 periods). Digestibilities of each type of diet were measured with the indigestible marker chromic oxide. Dry matter intakes were similar between diets (374–584 g · 30 kg^?1 · d^?1), even though dietary protein content was reduced from 44% to 29% of dry matter. Digestibility of dry matter was unaltered by these dietary changes (77% of high prey diet vs. 73% of chow diet), but fecal consistency changed to softer stools at lower intakes of prey. Estimated metabolizable energy intakes of wolves (501–674 kJ · kg^?0.75 · d^?1) were similar to the maintenance requirement for domestic dogs (525 kJ · kg^?0.75 · d^?1), suggesting a similar energy requirement for maintenance of the wolves. The metabolizable energy derived from protein in the high prey diets was 37%, whereas that of the chow diets was only 27%. These levels exceed estimates of protein requirements for maintenance (4.3–21.8%) and growth (11.5–20.3%) in domestic dogs and may thus exceed those of the wolves. Dietary management of maned wolves should minimize excess protein intake by limiting prey consumption and acclimating animals to extruded diets for domestic dogs. Further research is required to formulate diets for long-term management of cystinuria in maned wolves. © 1994 Wiley-Liss, Inc.     

Food habits of three carnivores in a mosaic landscape of São Paulo state,Brazil

São Paulo is the most developed state in Brazil, but despite intense land use changes, some mammal species still inhabit remnant fragments of native vegetation of the state. We used fecal analyses to investigate prey diversity, trophic niche breadth, and trophic niche overlap of pumas, ocelots, and maned wolves in protected and non-protected areas in São Paulo state. During 18 months, we inspected more than 10,000 km of roads and trails and collected 233 fecal samples. Maned wolves showed generalist food habit, ocelots were predominantly carnivores, and pumas were strict carnivores. The European hare, an exotic species which had not yet been reported in the study area, was identified in the feces of a puma. Trophic niche breadth was the lowest for maned wolves (BA?=?0.339) and the highest for pumas (BA?=?0.723). Trophic niche overlap was high between maned wolves and ocelots (O_jk?=?0.765) and between pumas and ocelots (O_jk?=?0.639). Significantly different diets of maned wolves and ocelots were observed between dry and rainy seasons. Our findings indicate that these three species may adapt their diets to the disturbed landscapes. This is the second study characterizing food habits of ocelots in Cerrado areas but the first considering a large number of samples.     

Characterization of reproductive cycles and adrenal activity in the black‐footed ferret (Mustela nigripes) by fecal hormone analysis

The reproductive cycle of the black‐footed ferret (Mustela nigripes) was characterized by enzyme immunoassay (EIA) analysis of ovarian fecal steroids (estradiol, progestins) in 29 females over two consecutive breeding seasons. Estrous status was determined by measuring the vulva size and examining the percentage of superficial cells in vaginal lavages. Mean fecal estradiol concentrations were correlated with vulval area (r = 0.370, P < 0.0001) and the percentage of superficial cells (r = 0.380, P < 0.0001). Ovulation resulted in a rise in fecal progestin concentrations 5 days after breeding that differed (P < 0.05) between pregnant (n = 14) and pseudopregnant (n = 12) females during the late luteal phase (days 12–40), with concentrations remaining higher in pregnant animals. Gestation length was 41.3 ± 0.7 days with 3.6 ± 0.4 kits produced per female. Litter size correlated significantly (P < 0.05) with fecal estradiol, but not progestins during the 12 to 40 days after breeding. Females failing to breed (n = 3) remained in estrus for 31 ± 6.2 days before ovulation induction with human chorionic gonadotropin. Adrenal activity in male (n = 4) and female (n = 6) black‐footed ferrets was monitored by quantifying fecal corticoid metabolites after a series of manipulations (physical restraint, intramuscular saline, intramuscular gel adrenocorticotropic hormone (ACTH), intramuscular liquid ACTH). A significant (P < 0.0001) increase in fecal corticoids above the pre‐treatment baseline occurred 20 to 44 hours after restraint (five of 10 animals), saline (six of nine), gel ACTH (seven of 10), and liquid ACTH (nine of 10) treatments. Immunoreactivity of high‐performance liquid chromatography–separated fecal elutes was compared using antibodies against cortisol and corticosterone. The cortisol EIA demonstrated immunoreactivity that co‐eluted with ³H‐cortisol, whereas a corticosterone radioimmunoassay detected a metabolite peak that co‐eluted with ³H‐corticosterone in addition to a slightly less polar and one considerably more polar peak. Despite recognizing different metabolites, both assays produced similar temporal profiles of corticoid excretion after manipulation. This study provides new information on the black‐footed ferret regarding differences in fecal steroid excretion patterns between pregnancy and pseudopregnancy and the potential application of fecal corticoid metabolite monitoring for evaluating responses to stressors associated with practices used in breeding management. Zoo Biol 20:517–536, 2001. © 2002 Wiley‐Liss, Inc.     

Aggression control in a bachelor herd of fringe‐eared oryx (Oryx gazella callotis), with melengestrol acetate: Behavioral and endocrine observations

Aggression control is becoming an important component in the management of animals in captivity, but rigorous quantification of aggressive behavior has heretofore been lacking. This study was done to assess the ability of melengestrol acetate (MGA) given with feed (1.54 mg/kg) to control aggression in a bachelor group of fringe‐eared oryx (Oryx gazella callotis). Systematic behavioral observations were conducted and fecal androgen content was measured for 42 and 90 days, respectively, before treatment, and during the 42 days of treatment. There was a significant reduction in concentrations of fecal androgen from 153 ± 6.0 to 95 ± 4.5 ng/g (T₆₆ = 7, P < 0.0001). This reduction in androgen excretion was apparent after the first week of treatment. There was measurable MGA excreted in the feces during treatment. Although treatment did not arrest all aggressive behaviors among animals, the decline in androgens and increase in MGA was accompanied by a significant reduction in several measures of agonistic behavior. Posturing, aggressive contact, pursuit, and submission occurred significantly less frequently after treatment, and there was also a reduction in fighting‐intention movements. Thus, both ritualized and nonritualized aspects of aggression were affected. Reductions in hormones and aggressive behaviors coincided temporally, suggestive of a potential causal relationship. Consistent with this hypothesis is a strong positive correlation between fecal androgen and total aggressive acts. This effect was not the result of a single behavioral element but occurred across several categories of agonistic behavior. Zoo Biol 20:375–388, 2001. © 2001 Wiley‐Liss, Inc.     

A note on the effect of the full moon on the activity of wild maned wolves, Chrysocyon brachyurus

It is well established in the scientific literature that animal prey species reduce their activity at times of high predation risk. In the case of nocturnal animals this occurs when there is a full moon; however, the response of predators to the changes in their prey behaviour is relatively unknown. Two responses are possible: (1) increase in search effort to maintain food intake; or (2) decrease in distance travelled due to either: (a) an effort to conserve energy or (b) increased kill efficiency. Using GPS tracking collars we monitored the distances travelled (which is representative of search effort) by three maned wolves during the night of the full and new moon for five lunar cycles (during the dry season). A Wilcoxon matched-paired test showed that the maned wolves travelled significantly less during the full compared to the new moon (p < 0.05). On average, during the 10 h of darkness during a full moon maned wolves travelled 1.88 km less than on a new moon. These data suggest that maned wolves respond to temporally reduced prey availability by reducing their distance travelled.     

Fecal corticoid monitoring in whooping cranes (Grus americana) undergoing reintroduction

We used radioimmunoassay to determine fecal corticoid concentrations and assess potential stress in 10 endangered whooping cranes (Grus americana) undergoing reintroduction to the wild. Fecal samples were collected shortly after hatching at a captive facility in Maryland, during field training in Wisconsin, and throughout a human‐led migration to Florida. After a 14‐day decline following hatching, fecal corticoid concentrations stabilized at baseline levels for the duration of the captive period, despite exposure to potentially stressful stimuli. Shipment of the cranes to the field training site was correlated with an eight‐ to 34‐fold increase in fecal corticoid concentrations, which returned to baseline levels within 1 week. Increases were positively correlated with age but not body weight at the time of shipping. Fecal corticoid concentrations during the training period increased slightly and exhibited greater variation than levels observed at the captive facility, but were well within expected norms based on previous studies. Fecal corticoid concentrations increased twofold following premigration physical examinations and placement of radiotransmitters, and persisted for up to 4 days before they returned to baseline levels. Though fecal corticoid concentrations and variation during the migration period were similar to training levels, there was an overall decline in fecal corticoid concentrations during the artificial migration. Acute stressors, such as capture, restraint, and severe storms, were associated with stress responses by the cranes that varied in accordance with lasting physical or psychological stimuli. The overall reintroduction process of costume‐rearing, ultralight aircraft habituation, training, and artificial migration was not associated with elevations in fecal corticoid concentrations suggestive of chronic stress. Zoo Biol 24:15–28, 2005. © 2005 Wiley‐Liss, Inc.     

Behavioral effects of environmental enrichment on harbor seals (Phoca vitulina concolor) and gray seals (Halichoerus grypus)

Zoos and aquariums have been incorporating environmental enrichment into their animal care programs for the past 30 years to increase mental stimulation and promote natural behaviors. However, most attempts to document the effects of enrichment on animal behavior have focused on terrestrial mammals. Staff at the National Aquarium in Baltimore conducted an investigation of the behavioral effects of enrichment on the seven harbor seals and two gray seals housed in the aquarium's outdoor seal exhibit. We expected that enrichment would change the amount of time the animals spent engaged in specific behaviors. The behaviors recorded were: resting in water, resting hauled out, maintenance, breeding display, breeding behavior, aggression, pattern swimming, random swimming, exploration, and out of sight. Activity levels (random swimming and exploration) were expected to increase, while stereotypic behaviors (pattern swimming) were expected to decrease. The frequency and duration of behaviors were documented for 90 hr in both the control phase (without enrichment) and the experimental phase (with enrichment). Statistically significant differences (P<0.05) in the time spent in pattern swimming, random swimming, exploration, and out of sight were observed between the two phases. With enrichment, pattern swimming and out of sight decreased, while random swimming and exploration behavior increased. These findings demonstrate that enrichment can promote behaviors (random swimming and exploration) that are likely to be normal for phocids in the wild, and that may contribute to the behavioral complexity of these seals in captivity. Zoo Biol 21:375–387, 2002. © 2002 Wiley‐Liss, Inc.     

Terrestrial predator alarm vocalizations are a valid monitor of stress in captive brown capuchins (Cebus apella)

The vocal behavior of captive animals is increasingly exploited as an index of well‐being. Here we show that the terrestrial predator alarm (TPA) vocalization, a robust and acoustically distinctive anti‐predation vocal response present in many mammal and bird species, offers useful information on the relative well‐being and stress levels of captive animals. In a 16‐week experiment evaluating the effects of varying levels of physical environmental enrichment (control < toys < foraging box < foraging box and toys) in the cages of eight singly housed adult male brown capuchins, we quantified the 1) emission rate of TPAs, 2) proportions of normal and abnormal behavior sample intervals, and 3) fecal and plasma cortisol levels. Variation in TPA emission across the experimental conditions was significant. We found significant reductions in the mean TPA production rate by the group in the enriched (toys, foraging box, and foraging box and toys) compared to the control condition; pre‐ and post‐experimental conditions, however, did not differ from the control condition. Mean TPA production by the group was also significantly positively correlated to mean group levels of fecal cortisol and proportion of abnormal behavior sample intervals, and significantly negatively correlated to the average proportion of normal behavior sample intervals in the group. Based on group means, plasma cortisol levels were positively, but not significantly, related to increasing TPA rate. At the level of the responses of an individual subject, however, the covariation between the vocal and non‐vocal behavioral measures and the cortisol assays seldom attained significance. Nevertheless, the direction of the relationships among these parameters within individual subjects typically mirrored those correlations based on group means. At both the group mean and individual levels, our results are consistent with the interpretation that in conditions of low environmental enrichment the study subjects were more stressed, and therefore more reactive to the presence of a threatening terrestrial stimulus (human observer), than when in more enriched conditions. We suggest that protocols to evaluate the effectiveness of enrichment for captive species other than brown capuchins could also profitably exploit TPAs as a first‐line monitor or as corroboratory evidence of current well‐being. Zoo Biol 18:295–312, 1999. © 1999 Wiley‐Liss, Inc.     

Accurate measurement of body weight and food intake in environmentally enriched male Wistar rats

Laboratory animals are crucial in the study of energy homeostasis. In particular, rats are used to study alterations in food intake and body weight. To accurately record food intake or energy expenditure it is necessary to house rats individually, which can be stressful for social animals. Environmental enrichment may reduce stress and improve welfare in laboratory rodents. However, the effect of environmental enrichment on food intake and thus experimental outcome is unknown. We aimed to determine the effect of environmental enrichment on food intake, body weight, behavior and fecal and plasma stress hormones in male Wistar rats. Singly housed 5–7‐week‐old male rats were given either no environmental enrichment, chew sticks, a plastic tube of 67 mm internal diameter, or both chew sticks and a tube. No differences in body weight or food intake were seen over a 7‐day period. Importantly, the refeeding response following a 24‐h fast was unaffected by environmental enrichment. Rearing, a behavior often associated with stress, was significantly reduced in all enriched groups compared to controls. There was a significant increase in fecal immunoglobulin A (IgA) in animals housed with both forms of enrichment compared to controls at the termination of the study, suggesting enrichment reduces hypothalamo‐pituitary‐adrenal (HPA) axis activity in singly housed rats. In summary, environmental enrichment does not influence body weight and food intake in singly housed male Wistar rats and may therefore be used to refine the living conditions of animals used in the study of energy homeostasis without compromising experimental outcome.