Little attention has been paid to the resting and sleeping behavior of zoo elephants so far. An important concern is when elephants avoid lying down, due to degenerative joint and foot disease, social structure, or stressful environmental changes. Inability or unwillingness to lie down for resting is an important welfare issue, as it may impair sleep. We emphasize the importance of satisfying rest in elephants by reviewing the literature on resting behavior in elephants (Loxodonta africana and Elephas maximus) as well as the documentation of four cases from European zoos and our own direct observations in a zoo group of four female African elephants during 12 entire days. The common denominator in the case reports is the occurrence of a falling bout out of a standing position subsequently to a cessation of lying rest for different periods of time. Although well-known in horses as "episodic collapse" or "excessive drowsiness," this syndrome has not been described in elephants before. To enable its detection, we recommend nocturnal video monitoring for elephant-keeping institutions. The literature evaluation as well as own observational data suggest an inverse relationship between lying rest and standing rest. Preventative measures consist of enclosure modifications that facilitate lying rest (e.g., sand hills) or standing rest in a leaning position as a substitute. Anecdotal observations suggest that the provision of appropriate horizontal environmental structures may encourage safe, sleep-conducive standing rest. We provide drawings on how to install such structures. Effects of providing such structures should be evaluated in the future.

Employing a range of neuroanatomical stains, we detail the organization of the main and accessory olfactory systems of the African wild dog. The organization of both these systems follows that typically observed in mammals, but variations of interest were noted. Within the main olfactory bulb, the size of the glomeruli, at approximately 350 μm in diameter, are on the larger end of the range observed across mammals. In addition, we estimate that approximately 3,500 glomeruli are present in each main olfactory bulb. This larger main olfactory bulb glomerular size and number of glomeruli indicates that enhanced peripheral processing of a broad range of odorants is occurring in the main olfactory bulb of the African wild dog. Within the accessory olfactory bulb, the glomeruli did not appear distinct, rather forming a homogenous syncytia‐like arrangement as seen in the domestic dog. In addition, the laminar organization of the deeper layers of the accessory olfactory bulb was indistinct, perhaps as a consequence of the altered architecture of the glomeruli. This arrangement of glomeruli indicates that rather than parcellating the processing of semiochemicals peripherally, these odorants may be processed in a more nuanced and combinatorial manner in the periphery, allowing for more rapid and precise behavioral responses as required in the highly social group structure observed in the African wild dog. While having a similar organization to that of other mammals, the olfactory system of the African wild dog has certain features that appear to correlate to their environmental niche.

Caring for all aspects of zoo elephants' well-being is considered a major challenge. Providing an appropriate flooring substrate to facilitate lying rest presents a meaningful part of a holistic management concept. Investigating the impact of a new sand flooring on the nocturnal resting behavior of a breeding group of seven African elephants living at one zoo revealed more total lying rest, longer bouts of lying rest and a reduced side preference in the adult females.With an average total daily lying rest of about 1.5-2.0 hrs, the investigated zoo elephants expressed longer lying rest compared to recently reported data from free-ranging individuals in Botswana. In addition, the presence of nursing calves in the observed elephant group seemed to impact the resting pattern of all group members, with around 60% of all lying bouts being discontinued after interruption by the youngsters. With respect to observed nursing during leaning rest, we encourage the installation of appropriate horizontal structures in breeding facilities to support leaning rest behavior of their female elephants. In doing so, zoos may improve rest quality of nursing females, and, in general, the welfare aspect of sleep for their elephants. K E Y W O R D S lying and leaning rest, sand flooring, zoo elephants ORCID Christian Schiffmann

The present study examines cortical neuronal morphology in the African lion (Panthera leo leo), African leopard (Panthera pardus pardus), and cheetah (Acinonyx jubatus jubatus). Tissue samples were removed from prefrontal, primary motor, and primary visual cortices and investigated with a Golgi stain and computer‐assisted morphometry to provide somatodendritic measures of 652 neurons. Although neurons in the African lion were insufficiently impregnated for accurate quantitative dendritic measurements, descriptions of neuronal morphologies were still possible. Qualitatively, the range of spiny and aspiny neurons across the three species was similar to those observed in other felids, with typical pyramidal neurons being the most prominent neuronal type. Quantitatively, somatodendritic measures of typical pyramidal neurons in the cheetah were generally larger than in the African leopard, despite similar brain sizes. A MARsplines analysis of dendritic measures correctly differentiated 87.4% of complete typical pyramidal neurons between the African leopard and cheetah. In addition, unbiased stereology was used to compare the soma size of typical pyramidal neurons (n = 2,238) across all three cortical regions and gigantopyramidal neurons (n = 1,189) in primary motor and primary visual cortices. Both morphological and stereological analyses indicated that primary motor gigantopyramidal neurons were exceptionally large across all three felids compared to other carnivores, possibly due to specializations related to the felid musculoskeletal systems. The large size of these neurons in the cheetah which, unlike lions and leopards, does not belong to the Panthera genus, suggests that exceptionally enlarged primary motor gigantopyramidal neurons evolved independently in these felid species.

The African wild dog is endemic to sub‐Saharan Africa and belongs to the family Canidae which includes domestic dogs and their closest relatives (i.e., wolves, coyotes, jackals, dingoes, and foxes). The African wild dog is known for its highly social behavior, co‐ordinated pack predation, and striking vocal repertoire, but little is known about its brain and whether it differs in any significant way from that of other canids. We employed gross anatomical observation, magnetic resonance imaging, and classical neuroanatomical staining to provide a broad overview of the structure of the African wild dog brain. Our results reveal a mean brain mass of 154.08 g, with an encephalization quotient of 1.73, indicating that the African wild dog has a relatively large brain size. Analysis of the various structures that comprise their brains and their topological inter‐relationships, as well as the areas and volumes of the corpus callosum, ventricular system, hippocampus, amygdala, cerebellum and the gyrification index, all reveal that the African wild dog brain is, in general, similar to that of other mammals, and very similar to that of other carnivorans. While at this level of analysis we do not find any striking specializations within the brain of the African wild dog, apart from a relatively large brain size, the observations made indicate that more detailed analyses of specific neural systems, particularly those involved in sensorimotor processing, sociality or cognition, may reveal features that are either unique to this species or shared among the Canidae to the exclusion of other Carnivora.