Do chimpanzee nests serve an anti-predatory function?

Sleep is a vulnerable state for animals as it compromises the ability to detect predators. The evolution of shelter construction in the great apes may have been a solution to the trade-off between restorative sleep and predation-risk, which allowed a large bodied ape to sleep recumbent in a safe, comfortable spot. In this article we review the evidence of predator pressure on great apes and specifically investigate the potential influence of predation-risk on chimpanzee nesting behavior by comparing nests between chimpanzees living in a habitat of several potential predators (Issa, Ugalla, Tanzania) and a habitat relatively devoid of predators (Fongoli, Senegal). Chimpanzees in Issa did not nest more frequently in forest vegetation than chimpanzees in Fongoli although forest vegetation is expected to provide greater opportunity for escape from terrestrial predators. Nor do chimpanzees in Issa nest in larger groups or aggregate together more than Fongoli chimpanzees, as would be expected if larger groups provide protection from or greater detection of predators. Nests in Issa also did not appear to provide greater opportunities for escape than nests in Fongoli. Chimpanzees in Issa nested more frequently within the same tree as other community members, which may indicate that these chimpanzees nest in greater proximity than chimpanzees in Fongoli. Finally, Issa chimpanzees built their nests proportionately higher and more peripherally within trees. The selection of high and peripheral nesting locations within trees may make Issa chimpanzees inaccessible to potential predators. Many factors influence nest site selection in chimpanzees, of which danger from terrestrial predators is likely to be one.

Termite fishing laterality in the Fongoli savanna chimpanzees (Pan troglodytes verus): further evidence of a left hand preference.

Whether nonhuman primates show population-level handedness is a topic of much scientific debate. A previous study of handedness for termite fishing reported population-level left handedness in the chimpanzees from Gombe National Park, Tanzania. In the current study, we examined whether similar hand preferences were evident in a savanna-dwelling chimpanzee population with regards to termite fishing. Hand preference data were collected for 27 chimpanzees from February 2007 through July 2008 and November 2011 through January 2012 in southeastern Senegal. Overall, the Fongoli chimpanzees demonstrate a trend toward population-level handedness, though the results did not reach conventional levels of statistical significance likely due to the limited sample size. Fongoli chimpanzees showed the same pattern of left hand preference as reported at Gombe and the two populations did not differ significantly. When the data were combined across all studies, wild chimpanzees showed a population-level left hand preference for termite fishing.

Occam's razor revisited: guenon species morphology supports evidence for an African influence in Bronze Age Aegean fresco primate iconography from Akrotiri, Thera.

In a recent exchange, Pareja et al. (Primates 61: 159-168, 2020a; Primates 61: 767-774, 2020b) and Urbani and Youlatos (Primates, https://doi.org/10.1007/s10329-020-00825-2 , 2020a) dispute the re-interpretation of the primate species depicted in a Bronze Age fresco from Room 6 of Building Complex Beta at Akrotiri, Thera. They review the history of interpretations of this artwork and combine the expertise of scholars that traditionally focus on such research with the scientific expertise of primatologists to reexamine the artwork. Additionally, they emphasize the morphological traits exhibited by these painted primates. We review and expand their list of candidate primates here in a decision table to demonstrate that the African link is better supported by the morphological traits than the Asian one proposed by Pareja et al. (2020a, b). Using such evidence, we show that other guenons of the tribe Cercopithecini, such as L'Hoest's monkey (Allochrocebus lhoesti) and the Diana monkey (Cercopithecus diana), provide equal support for the African link as the vervet monkey proposed by Urbani and Youlatos (2020a). However, the historical context supports the traditional interpretation that the Akrotiri fresco depicts vervet monkeys from this region. This discourse provides an open forum for scholars in various fields to contribute to an important problem that crosses disciplinary boundaries.

Savanna chimpanzee (Pan troglodytes verus) nesting ecology at Bagnomba (Kedougou, Senegal).

We studied the nesting behavior of the critically endangered West African chimpanzee (Pan troglodytes verus). We assumed that the nesting data stemmed from a single, unhabituated community at the Bagnomba hill site in the savanna-woodlands of southeastern Senegal. The aim of this study was to examine chimpanzees' nesting habits in terms of the tree species utilized and sleeping nest heights. We recorded a total of 550 chimpanzee nests at Bagnomba between January 2015 and December 2015. The chimpanzees here made nests in particular tree species more often than others. The majority of nests (63%) were in two tree species: Diospyros mespiliformis and Pterocarpus erinaceus. The average height of nesting trees was 10.54 m (SD 3.91, range, 0.0-29.0 m) and average nest height was 7.90 m (SD 3.62, range, 0.0-25.0 m). The result of a linear regression analysis (r = 0.7874; n = 550; p < 0.05) is consistent with a preference for nesting at a particular height. Bagnomba chimpanzees rarely made ground nests (0.36% of nests), but the presence of any ground nesting was unexpected, given that at least one leopard (Panthera pardus) also occupied the hill. This knowledge will enable stakeholders involved in the protection of chimpanzees specifically and of biodiversity in general to better understand chimpanzee ecology and inform a conservation action plan in Senegal where the survival of this species is threatened.

Evidence of cave use by savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal: implications for thermoregulatory behavior.

Much attention has been paid to how humans both adapt and acclimate to heat stress, primarily due to the relevance of these issues to hominid evolution in open Plio-Pleistocene environments. However, little is known about the responses of human's closest living relative, the chimpanzee (Pan troglodytes), to similar environmental stressors. In southeastern Senegal, one of the hottest and driest habitats that chimpanzees (P. t. verus) live in today, apes rely on behavioral mechanisms of dealing with thermal stress. Chimpanzees' use of caves was based primarily on indirect evidence (feeding traces, feces, and hairs) gathered from one cave from January to December 2004, but data from observational records collected from May 2001 through March 2006 supplement these data. The hypothesis that chimpanzees' use of caves is a response to heat was tested by collecting data on temperatures within the largest cave and in different habitats used by chimpanzees, such as gallery forest and woodland. Results indicate that chimpanzees primarily use caves as shelters during the hottest times of year and that caves are consistently and significantly cooler than open habitats. Insight into the way that chimpanzees in Senegal cope with extreme temperatures may help us to better understand the behavior of early hominids in such an environment.

Fetal cardiology: changing the definition of critical heart disease in the newborn.

Infants born with congenital heart disease (CHD) may require emergent treatment in the newborn period. These infants are likely to benefit the most from a prenatal diagnosis, which allows for optimal perinatal planning. Several cardiac centers have created guidelines for the management of these high-risk patients with CHD. This paper will review and compare several prenatal CHD classification systems with a particular focus on the most critical forms of CHD in the fetus and newborn. A contemporary definition of critical CHD is one which requires urgent intervention in the first 24 h of life to prevent death. Such cardiac interventions may be not only life saving for the infant but also decrease subsequent morbidity. Critical CHD cases may require delivery at specialized centers that can provide perinatal, obstetric, cardiology and cardiothoracic surgery care. Fetuses diagnosed in mid-gestation require detailed fetal diagnostics and serial monitoring during the prenatal period, in order to assess for ongoing changes and identify progression to a more severe cardiac status. Critical CHD may progress in utero and there is still much to be learned about how to best predict those who will require urgent neonatal interventions. Despite improved therapeutic capabilities, newborns with critical CHD continue to have significant morbidity and mortality due to compromise that begins in the delivery room. Fetal echocardiography is the best way to predict the need for specialized care at birth to improve outcome. Once the diagnosis is made of critical CHD, delivery at the proper time and in appropriate institution with specific care protocols should be initiated. More work needs to be done to better delineate the risk factors for progression of critical CHD and to determine which newborns will require specialized care. The most frequently described forms of critical CHD requiring immediate intervention include hypoplastic left heart syndrome with intact or severely restricted atrial septum, obstructed total anomalous pulmonary venous return and transposition of the great arteries with restrictive atrial septum.

New evidence on the tool-assisted hunting exhibited by chimpanzees (Pan troglodytes verus) in a savannah habitat at Fongoli, Sénégal.

For anthropologists, meat eating by primates like chimpanzees (Pan troglodytes) warrants examination given the emphasis on hunting in human evolutionary history. As referential models, apes provide insight into the evolution of hominin hunting, given their phylogenetic relatedness and challenges reconstructing extinct hominin behaviour from palaeoanthropological evidence. Among chimpanzees, adult males are usually the main hunters, capturing vertebrate prey by hand. Savannah chimpanzees (P. t. verus) at Fongoli, Sénégal are the only known non-human population that systematically hunts vertebrate prey with tools, making them an important source for hypotheses of early hominin behaviour based on analogy. Here, we test the hypothesis that sex and age patterns in tool-assisted hunting (n=308 cases) at Fongoli occur and differ from chimpanzees elsewhere, and we compare tool-assisted hunting to the overall hunting pattern. Males accounted for 70% of all captures but hunted with tools less than expected based on their representation on hunting days. Females accounted for most tool-assisted hunting. We propose that social tolerance at Fongoli, along with the tool-assisted hunting method, permits individuals other than adult males to capture and retain control of prey, which is uncommon for chimpanzees. We assert that tool-assisted hunting could have similarly been important for early hominins.

Social and seasonal influences on reproductive biology in male moustached tamarins (Saguinus mystax).

In several primate taxa there is evidence that the social and physical environment can exert a significant effect on reproductive behavior and biology. In this paper we examine social and physiological factors influencing group composition and reproduction in free-ranging moustached tamarin monkeys (Saguinus mystax mystax). This species is characterized by cooperative care of the young and a breeding system that includes both polyandrous and polygyandrous matings. Body measurements collected on adult males residing in multimale groups indicate marked within-group differences in testes volume. In 12 of 17 groups examined, testes volume of at least two resident adult males differed by 21-174%. Among these males, testes volume was not correlated with either body weight or adult age class. We also examine whether factors such as time of year had an effect on reproductive condition. An analysis of body measurements of 128 adult male and 127 adult female moustached tamarins, wild-trapped and released in northeastern Peru, indicates cyclic changes in genital size. For males, mean monthly testes volume in July (712 mm3) was twice that recorded in June (351 mm3). Females exhibited a similar pattern. Although endocrine information on intra- and intersexual social effects on fertility are unavailable for S. mystax, given the high degree of social cooperation and lack of overt aggression among adult male group members, we offer the possibility that resident male moustached tamarins compete for access to the groups' lone breeding female through socially induced reproductive suppression and sperm competition. © 1996 Wiley-Liss, Inc.

Demographic and reproductive patterns in moustached tamarin monkeys (Saguinus mystax): Implications for reconstructing platyrrhine mating systems.

In this paper we address a series of questions concerning reproductive opportunities, kinship, dispersal, and mating patterns in free-ranging moustached tamarin monkeys (Saguinus mystax). Between 1980 and 1990 information on group size, composition, and migration patterns was collected on marked groups of moustached tamarins inhabiting Padre Isla, an island in the Amazon Basin of northeastern Peru. In 1990, 86% of 114 animals residing in 16 social groups were trapped, examined, and released. Mean group size was 7.0, including 2.2 adult males and 2.0 adult females. None of these groups was characterized by a single adult male-female pair. In groups with more than one adult female, only the oldest female produced offspring. An examination of dispersal patterns indicates that transfers between groups were common and fell into several categories, including immigration of individual males and females, simultaneous transfer of pairs of subadult and/or adult males (sometimes relatives) into the same social groups, and group fissioning in which males and females of the splinter group join another small social group. We have no unambiguous cases of 2 adult/subadult females migrating together into the same social group. All 6 groups for which reproductive data were available were characterized by either a polyandrous or polygynous (polygyandrous) mating pattern. The results of this study indicate that moustached tamarins reside in small multimale multifemale groups that are likely to contain both related and unrelated adult group members. Kinship and social ties among males appear to be stronger and more longlasting than kinship and social ties among females. We contend that the modal mating system of moustached and many other tamarins is not monogamous, and offer the possibility that cooperative infant care and mating system flexibility in callitrichines evolved from a polygynous mating pattern. © 1993 Wiley-Liss, Inc.

Abnormal cerebral microstructure in premature neonates with congenital heart disease.

BACKGROUND AND PURPOSE: Abnormal cerebral microstructure has been documented in term neonates with congenital heart disease, portending risk for injury and poor neurodevelopmental outcome. Our hypothesis was that preterm neonates with congenital heart disease would demonstrate diffuse cerebral microstructural abnormalities when compared with critically ill neonates without congenital heart disease. A secondary aim was to identify any association between microstructural abnormalities, white matter injury (eg, punctate white matter lesions), and other clinical variables, including heart lesions. MATERIALS AND METHODS: With the use of tract-based spatial statistics, an unbiased, voxelwise method for analyzing diffusion tensor imaging data, we compared 21 preterm neonates with congenital heart disease with 2 cohorts of neonates without congenital heart disease: 28 term and 27 preterm neonates, identified from the same neonatal intensive care unit. RESULTS: Compared with term neonates without congenital heart disease, preterm neonates with congenital heart disease had microstructural abnormalities in widespread regions of the central white matter. However, 42% of the preterm neonates with congenital heart disease had punctate white matter lesions. When neonates with punctate white matter lesions were excluded, microstructural abnormalities remained only in the splenium. Preterm neonates with congenital heart disease had similar microstructure to preterm neonates without congenital heart disease. CONCLUSIONS: Diffuse microstructural abnormalities were observed in preterm neonates with congenital heart disease, strongly associated with punctate white matter lesions. Independently, regional vulnerability of the splenium, a structure associated with visual spatial function, was observed in all preterm neonates with congenital heart disease.

Arboreal nesting as anti-predator adaptation by savanna chimpanzees (Pan troglodytes verus) in southeastern Senegal.

Chimpanzees (Pan troglodytes) make nests for resting and sleeping, which is unusual for anthropoid primates but common to all great apes. Arboreal nesting has been linked to predation pressure, but few studies have tested the adaptive nature of this behavior. We collected data at two chimpanzee study sites in southeastern Senegal that differed in predator presence to test the hypothesis that elevated sleeping platforms are adaptations for predator defense. At Assirik in the Parc National du Niokolo-Koba, chimpanzees face four species of large carnivore, whereas at Fongoli, outside national park boundaries, humans have exterminated almost all natural predators. We quantified the availability of vegetation at the two sites to test the alternative hypothesis that differences in nesting reflect differences in habitat structure. We also examined possible sex differences in nesting behavior, community demographic differences, seasonality and nest age differences as variables also potentially affecting nest characteristics and nesting behavior between the two sites. Chimpanzees at Fongoli nested at lower heights and farther apart than did chimpanzees at Assirik and sometimes made nests on the ground. The absence of predators outside of the national park may account for the differences in nest characteristics at the two sites, given the similarities in habitat structure between Fongoli and Assirik. However, Fongoli chimpanzees regularly build arboreal nests for sleeping, even under minimal predation pressure, and this requires explanation.

Do "savanna" chimpanzees consume C4 resources?

Several stable carbon isotopic studies have shown that South African australopiths consumed significant quantities of C(4) resources (tropical grasses, sedges, or animals that eat those foods), but relatively little is known about the consumption of such resources by chimpanzees. Here, we present stable carbon isotopic data for 36 chimpanzee hair samples from Fongoli, one of the driest and most open areas inhabited by chimpanzees. These data suggest that the Fongoli chimpanzees consume little in the way of C(4) vegetation or animals that eat such vegetation, even though these resources are locally abundant and preferred fruits are more widely scattered than at most chimpanzee study sites. The homogeneity of the Fongoli results is especially striking and recalls the narrow isotopic distribution of stenotopic savanna mammals. This is in stark contrast to what has been observed for australopiths, which had highly variable diets and consumed about 35% C(4) vegetation on average. Carbon isotope data for modern and fossil Papio depict a dietarily variable genus with a tendency to consume C(4) vegetation. This trophic flexibility, or willingness to consume C(4) savanna resources, may make Papio a more profitable ecological analog for australopiths than chimpanzees.

Chimpanzees use tools to harvest social insects at Fongoli, Senegal.

Use of flexible probes to fish for macrotermitine termites and manufactured wands to dip for doriline ants is reported for a new site of chimpanzee field study. The flexible probes of vegetation used in termite fishing and ant dipping by the chimpanzees of Fongoli, in southeastern Senegal, are similar to those used at Assirik (Senegal) and Gombe (Tanzania). Based on the principle that form reflects function, we predict that ant dipping when seen will prove to be the two-handed technique.

Locomotor activity differences between sympatric patas monkeys (Erythrocebus patas) and vervet monkeys (Cercopithecus aethiops): implications for the evolution of long hindlimb length in Homo.

Homo erectus is notable for its taller stature and longer lower limbs relative to earlier hominids, but the selective pressures favoring such long limbs are unclear. Among anthropoid primates, patas monkeys (Erythrocebus patas) and extant hominids share several extreme characteristics involved with foraging and movement, including the relatively longest lower limb proportions, longest daily travel distances and largest home ranges for their body or group size, occupancy of some of the driest habitats, and very efficient thermoregulatory systems. We suggest that patas monkeys are an appropriate behavioral model with which to speculate on the selective pressures that might have operated on H. erectus to increase lower limb length. Here, in a comparison of the locomotor activities of patas monkeys and sympatric, closely related vervet monkeys (Cercopithecus aethiops), we provide evidence for the hypothesis that patas use their long stride more to increase foraging efficiency while walking than to run, either from predators or otherwise.

Survey of savanna chimpanzees (Pan troglodytes verus) in Southeastern Sénégal.

A survey of the western subspecies of chimpanzee (Pan troglodytes verus) was conducted from 1 February to 9 April 2000 in Sénégal, West Africa, by the Miami Assirik Pan Project (MAPP). In addition to the Assirik area of the Parc National du Niokolo Koba (PNNK), areas south and east of the park were surveyed. Nests made by chimpanzees were used to estimate chimpanzee distribution and densities. Within the PNNK, chimpanzees were estimated to occur at an average of 0.13 individuals/km(2). Chimpanzee nests were recorded in nine of 10 locales surveyed outside of the PNNK, as well as within the park. Data on 994 nests made by chimpanzees were recorded outside the PNNK, while 736 nests were recorded inside the park. Nest density in areas surveyed outside the PNNK, such as Bandafassi, Tomboronkoto, and Segou, was comparable to that of Assirik in habitats where nests were concentrated (i.e., evergreen gallery forest). The purpose of MAPP was to initiate long-term research of chimpanzees in southeastern Sénégal, as a follow-up to the Stirling African Primate Project (SAPP) of the 1970s. We sought to replicate the standards set by the SAPP project, except when technological innovations allowed improvement in data collection procedures (e.g., the global positioning system (GPS)).

Genotyping aids field study of unhabituated wild chimpanzees.

Prolonged habituation times for wild great apes delay the collection of behavioral and environmental data, sometimes for years. However, genotyping of noninvasively collected feces can provide useful socioecological information in the meantime. We tested this premise on an unhabituated wild population of western chimpanzees (Pan troglodytes verus) at Mont Assirik, Senegal. Genotyping yielded information on kinship, group size, party size and composition, sex ratio, and ranging.

Comparing measures of travel distances in primates: methodological considerations and socioecological implications.

Travel costs can influence numerous aspects of the lives of primates, including net energy balance (and therefore reproductive success of females) and maximum group size. Despite their potential impact, there has been no systematic comparison of different measures of travel distance. We compared three measures of travel distance in 30 min (actual distance of individuals, straight-line distance of individuals, and straight-line distance of groups) and their ratios in a small group and a large group of vervet monkeys (Cercopithecus aethiops) and between the large group of vervets and a group of patas monkeys (Erythrocebus patas) of roughly similar size. The large group of vervets traveled farther than the small group regardless of the measure used, but the ratios of the different measures were not significantly different between those groups. Patas monkeys traveled significantly farther than the large group of vervets regardless of the measure used. In both vervets and patas, straight-line distances of individuals (ISLD) and groups (GSLD) underestimated actual distances traveled by individuals (IAD), but the degree to which they did so differed between species. IAD is more accurate than the other two measures and is preferred for studies of energetics and individual reproductive success, although ISLD or GSLD may be substituted when the ratios of IAD/ISLD or IAD/GSLD do not differ between groups or species. The ratio of IAD/ISLD was larger in vervets than in patas, suggesting that individual vervets meander more over short periods of time than patas. The ratio of ISLD/GSLD was larger in patas than in vervets, suggesting that patas move at angles or across the group's center-of-mass whereas vervets move more consistently along with others in their group. This has implications for the formation of spatial subgroups and alliances within groups.

Characterization of leptospiral outer membrane lipoprotein LipL36: downregulation associated with late-log-phase growth and mammalian infection.

We report the cloning of the gene encoding a 36-kDa leptospiral outer membrane lipoprotein, designated LipL36. We obtained the N-terminal amino acid sequence of a staphylococcal V8 proteolytic-digest fragment in order to design an oligonucleotide probe. A Lambda-Zap II library containing EcoRI fragments of Leptospira kirschneri DNA was screened, and a 2.3-kb DNA fragment which contained the entire structural lipL36 gene was identified. Several lines of evidence indicate that LipL36 is lipid modified in a manner similar to that of LipL41, a leptospiral outer membrane lipoprotein we described in a previous study (E. S. Shang, T. A. Summers, and D. A. Haake, Infect. Immun. 64:2322-2330, 1996). The deduced amino acid sequence of LipL36 would constitute a 364-amino-acid polypeptide with a 20-amino-acid signal peptide, followed by an L-X-Y-C lipoprotein signal peptidase cleavage site. LipL36 is solubilized by Triton X-114 extraction of L. kirschneri; phase separation results in partitioning of LipL36 exclusively into the hydrophobic, detergent phase. LipL36 is intrinsically labeled during incubation of L. kirschneri in media containing [3H]palmitate. Processing of LipL36 is inhibited by globomycin, a selective inhibitor of lipoprotein signal peptidase. After processing, LipL36 is exported to the outer membrane along with LipL41 and lipopolysaccharide. Unlike LipL41, there appears to be differential expression of LipL36. In early-log-phase cultures, LipL36 is one of the most abundant L. kirschneri proteins. However, LipL36 levels drop considerably beginning in mid-log phase. LipL36 expression in vivo was evaluated by examining the humoral immune response to leptospiral antigens in the hamster model of leptospirosis. Hamsters surviving challenge with culture-adapted virulent L. kirschneri generate a strong antibody response to LipL36. In contrast, sera from hamsters surviving challenge with host-adapted L. kirschneri do not recognize LipL36. These findings suggest that LipL36 expression is downregulated during mammalian infection, providing a marker for studying the mechanisms by which pathogenic Leptospira species adapt to the host environment.