Characterization of the behavior and reproductive endocrinology of giant river otters (Pteronura brasiliensis) in managed care

Assessment of Captive Environment for Oriental Small-Clawed Otters (Aonyx cinereus) in Otter Cafés in Japan

This study investigates the captive environments of oriental small-clawed otter (OSO; Aonyx cinereus) cafés in Japan, aiming to identify discrepancies with established welfare guidelines. Improved management of these commercial facilities could raise awareness about the difficulties of keeping OSOs as pets and enhance their welfare. Utilizing the role of commercial facilities in public outreach, we consider that the rigorous implementation of proper care practices in these establishments could help mitigate the increasing demand for OSOs domestically and contribute to the conservation of the OSO. In this study, we focused on the critical aspects of the captive environment necessary to maintain the psychological well-being of OSOs and evaluated the captive environments of OSOs housed in animal cafés for OSO welfare using non-invasive methods. Based on zoo husbandry standards, it was found that there were deficiencies in aquatic environments and solitary housing conditions; however, the enrichment tools aligned with the guidelines. The results suggest that deviations from the recommended elements in the environment of OSOs in captivity are associated with a tendency of these OSOs to develop various diseases. It is deemed necessary to amend the regulations governing animal-handling businesses to include welfare criteria, and it is considered essential for each establishment to operate only after ensuring sufficient welfare for the OSOs.

Visitors and observers otter-ly influence the behavior and enclosure use of zoo-housed giant otters

The potential impact of human presence on captive animal behavior has recently been the focus of considerable research interest, especially following 2020 and 2021 periods of enforced closure as a result of COVID-19 opening restrictions. It is important to investigate whether human presence represents an enriching or stressful stimulus to a range of zoo-housed species. In 2020, during an easing of lockdown restrictions, investigations of the "visitor effect" and "observer effect" were carried out, using the giant otter (Pteronura brasiliensis) as a model species. To investigate the impact of both visitor and observer presence, otter behavior and space use was recorded for a pair of on-show and a pair of off-show otters. Observations were conducted using either a human observer, or cameras, allowing the researchers to investigate otter behavior when no one was present at the exhibits. The Electivity Index was used to assess the otters' use of four enclosure zones. Overall, otter behavior was significantly impacted by observer presence, though the impact of an observer differed between individual otters. Visitors had a minimal effect on otter enclosure use, whereas observers had a greater impact, whereby otters used their pools less frequently and houses more frequently when observers were present. However, this change in zone use differed between individuals, with more dominant otters tending to make use of indoor zones more often when observers were present. Zoos should consider the potential impact of human presence on their animals and use both behavior and space use when conducting their investigations.

Quantification of immunoreactive testosterone and estradiol-17ß metabolites to identify the sex of Neotropical otters (Lontra longicaudis annectens) in the field

Before there was use of ultrasonographic imaging, determination of the ratio of estrogens to androgens in the same individual was a technique used for differentiating the sex of monomorphic animals in captivity, with larger estrogen concentrations in the females. Due to species-specific differences in both concentration and changes throughout the year of these hormones, corroboration of the method is needed in each case. In this study, there was use of a chemo-immuno assay to quantify sex steroids in fecal samples collected from seven (five females and two males) Neotropical otters, Lontra longicaudis. The reproductive season for this species was determined to be between October and March, with increased estradiol in the females and relatively greater concentrations of testosterone in the males as compared with other seasons of the year. Results from utilization of a k-means analysis procedure indicated that the use of steroid ratios in fecal samples to differentiate otter sex is an effective technique when there are evaluations during the breeding season. The estrogen to androgen ratios during this period, however, are the inverse of what was expected, with there being larger testosterone concentrations in the female otters. The ratio of estrogens to androgens in feces of captive otters can be effectively used to determine the sex of otters in the field. We propose this method is reliable for sex determination in wild otter populations during the reproductive season.