Do zoo animals use off-exhibit areas to avoid noise? A case study exploring the influence of sound on the behavior, physiology, and space use of two pied tamarins (Saguinus bicolor).

Noise can be a known stressor but our understanding of its effects on animals living in zoo environments remains limited. Although exposure to loud, chronic noise may be expected to negatively impact welfare, providing access to quiet areas to escape loud noise may buffer these negative effects. In this study, we explored the benefits of access to quiet, off-exhibit areas for animals living in a chronically loud sound environment. Two pied tamarins (Saguinus bicolor) living near a large waterfall feature that emitted loud, chronic noise were experimentally exposed to varying sound levels during 2-week treatment conditions. Baseline conditions (waterfall feature on and access to quiet, off-exhibit areas), were followed by a Quiet sound condition (waterfall off), a Loud sound condition (waterfall on and a speaker in the off-exhibit area playing volume-matched white noise), and a final Baseline condition. During Baseline conditions, sound levels were greater than 10 dBA higher in the exhibit than in the off-exhibit area (i.e., roughly twice as loud). The number of visitor groups present during behavior observations were consistent throughout the study. Both tamarins modified their space use during treatment conditions. Under Baseline conditions, both individuals showed frequent usage of quiet, off-exhibit areas. During the Quiet and Loud conditions, where sound levels were generally consistent across spaces, both individuals used off-exhibit areas less and their use of exhibit and off-exhibit areas was not significantly different than would be expected by chance, given the size of the areas. Additional behavioral changes were minimal. No significant differences in fecal glucocorticoid metabolites were observed. Although the monkeys in this study appeared to avoid noise, the overall impact on welfare appeared to be minimal considering the limited behavioral and hormonal changes observed. This study highlights the potential benefits of off-exhibit spaces as a quiet refuge from noise in the zoo environment.

Do zoo-housed primates retreat from crowds? A simple study of five primate species.

An animal's welfare state is directly influenced by the mental state, which is shaped by experiences within the environment throughout the animal's life. For zoo-housed animals, visitors to the zoo are a large part of that environment and a fluctuating influence within it. This study examines the impact of zoo visitors on the space use of five species of zoo-housed primates (Eastern black-and-white colobus monkeys, Colobus guereza, n = 5, Allen's swamp monkeys, Allenopithecus nigroviridis, n = 2, DeBrazza's monkeys, Cercopithecus neglectus, n = 3, Bolivian gray titi monkeys, Callicebus donacophilus, n = 3, and crowned lemurs, Eulemur coronatus, n = 3). Specifically, we considered whether primates' distance from visitor areas changed as crowd sizes increased. Data were collected using the ZooMonitor app. Observers recorded spatial coordinates for each animal over periods ranging from 12 to 32 months. Data were analyzed using two types of regression models (linear and logistic) to examine the influence of visitors on the location of the primates. Both analyses revealed a statistically significant but small decrease in primate distance from visitor viewing glass as the number of visitors increased. Behavioral indicators of welfare were also unaffected by the presence of visitors. These results suggest that, with additional validation, distance from visitors may be one promising, simple way to evaluate the influence of visitors on primate welfare.

Mapping Shade Availability and Use in Zoo Environments: A Tool for Evaluating Thermal Comfort.

For many species in zoos, particularly megafauna vulnerable to heat stress, shade is a key environmental resource. However, shade availability has received comparatively less attention than other aspects of the zoo environment. In this study, we share a simple low-cost approach that we applied to document shade availability across 33 zoo enclosures. We then combined these assessments with behavioral observations of enclosure use and shade-seeking behavior during summer months in a case study focused on Sichuan takin (Budorcas taxicolor tibetana) (n = 3), a large cold-adapted bovid. Behavioral observations were conducted before and after installation of a shade sail for the takin. Results indicated that shade availability varied widely across zoo enclosures, with the percent of shaded space ranging from 85 % to 22 % across enclosures during summer months. Shade was a dynamic resource and increased throughout the year and fluctuated across the day, with the least shade available midday. Takin showed general preferences for shaded areas near the walls of their enclosure but were observed using newly available shade from the shade sail after its installation. These accessible methods can be easily applied to assess shade within existing enclosures, evaluate enclosure modifications, and provide guidance for the design of new enclosures.

Fecal glucocorticoid metabolite responses to management stressors and social change in four species of callitrichine monkeys.

The use of enzyme immunoassays (EIA) for the non-invasive measurement of glucocorticoids provides a valuable tool for monitoring health and welfare in sensitive species. We validated methods for measuring fecal glucocorticoid metabolites (FGM) using the response to veterinary exams for four species of callitrichine monkeys: golden lion tamarin (Leontopithecus rosalia, n = 7), callimico (Callimico goeldii, n = 2), pied tamarin (Saguinus bicolor, n = 2), and white-fronted marmoset (Callithrix geoffroyi, n = 2). Routine veterinary exams were performed for the golden lion tamarins and callimicos, but exams for the pied tamarins and white-fronted marmosets were prompted by the death of a social partner. Prior to veterinary exams, fecal markers were evaluated to allow collection of individual samples and estimate approximate gut transit times. Based on this assessment, individual markers were fed in the afternoon, and fresh morning fecal samples were collected throughout this study. Following a veterinary exam, FGM increased roughly 3- to 28-fold above baseline in all species. Although FGM for most species returned to baseline concentrations within 24-48 h, the marmosets exhibited a progressive increase in FGM after an exam in response to the death of a breeding female and subsequent hand-rearing of a neonate. Individual differences were noted in the callimicos and tamarins, with higher baseline FGM levels in females vs. males, although small sample size precluded a clear determination of sex differences. To our knowledge, this is the first study to measure FGM in callimicos and white-fronted marmosets and the first to compare FGM across callitrichine species. These findings highlight the broad applicability of this EIA to measure the stress response of callitrichine monkeys. The progressive increase in FGM in the marmosets during hand-rearing of a neonate suggests that care should be taken to minimize this disturbance as much as possible.

Behavioral thermoregulation in a group of zoo-housed colobus monkeys (Colobus guereza).

Although wild primates are known to modify behavior in response to thermal stress, less is known about behavioral thermoregulation in zoo-housed primates. Zoo exhibits expose individuals to unique thermal environments and may constrain the thermoregulatory strategies available to individual animals. In this study, we observed a group of seven colobus monkeys (Colobus guereza) living on a concrete "Monkey Island" style exhibit that featured limited shade and limited arboreal space. Behaviors were recorded using continuous focal animal sampling (n = 63 days, 97.7 hr). Logistic regression revealed 23°C was the temperature at which monkeys began resting more in shade than in sun. When temperatures exceeded 23°C, animals spent more time in open sitting postures with limbs extended from the body; sat less frequently in closed, hunched postures; spent more time in social contact; and performed more self-directed behaviors. Exhibit use also shifted under higher temperatures, with more time spent in areas with shade and lower surface temperatures. Lastly, when provided with access to an indoor holding area, the colobus monkeys spent more than half the time indoors when temperatures exceeded 23°C, yet only 10% of their time indoors when the temperature was below this value. Although postural changes have been reported in wild colobus, the postural and other behavioral changes observed in the current study occurred at temperatures lower than expected based on the published thermoneutral zone of colobus monkeys and highlight the importance of considering the specific thermoregulatory responses of zoo animals.

Motor planning in primates.

Vaesen asks whether goal maintenance and planning ahead are critical for innovative tool use. We suggest that these aptitudes may have an evolutionary foundation in motor planning abilities that span all primate species. Anticipatory effects evidenced in the reaching behaviors of lemurs, tamarins, and rhesus monkeys similarly bear on the evolutionary origins of foresight as it pertains to tool use.

Monkey see, monkey plan, monkey do: the end-state comfort effect in cotton-top tamarins (Saguinus oedipus).

The way human adults grasp objects is typically influenced by their knowledge of what they intend to do with the objects. This influence is reflected in the end-state comfort effect: Actors adopt initially uncomfortable postures to accommodate later task demands. Although many experiments have demonstrated this effect, to the best of our knowledge its phylogenetic roots have not been investigated. In two experiments, we tested whether 9 cotton-top tamarin monkeys would show the end-state comfort effect. We did so by presenting the monkeys with a small cup containing a marshmallow. The cup was suspended in different orientations. The monkeys inhibited their natural grasping tendencies and adopted unusual grasping postures to accommodate subsequent task requirements, thus demonstrating the end-state comfort effect. This outcome provides evidence for more sophisticated motor planning than has previously been ascribed to this and related species.