Patterns of mineral lick visitation by spider monkeys and howler monkeys in Amazonia: are licks perceived as risky areas?

Mineral licks--also known as "salados," "saladeros," or "collpas"--are specific sites in tropical and temperate ecosystems where a large diversity of mammals and birds come regularly to feed on soil. Although the reasons for vertebrate geophagy are not completely understood, animals are argued to obtain a variety of nutritional and health benefits from the ingestion of soil at mineral licks. We studied the temporal patterns of mineral lick use by white-bellied spider monkey (Ateles belzebuth) and red howler monkey (Alouatta seniculus) in a lowland rain forest in Amazonian Ecuador. Using camera and video traps at four different mineral licks, combined with behavioral follows of one group of spider monkeys, we documented rates of mineral lick visitation by both primate species and the relative frequency and intensity of mineral lick use by spider monkeys. On the basis of 1,612 days and 888 nights of mineral lick monitoring, we found that A. belzebuth and A. seniculus both visit mineral licks frequently throughout the year (on average ～14% of days for both species), and mineral lick visitation was influenced by short-term environmental conditions (e.g. sunny and dry weather). For spider monkeys, the area surrounding the lick was also the most frequently and most intensively used region within the group's home range. The fact that spider monkeys spent long periods at the lick area before coming to the ground to obtain soil, and the fact that both species visited the lick preferentially during dry sunny conditions (when predator detectability is presumed to be relatively high) and visited simultaneously more often than expected by chance, together suggest that licks are indeed perceived as risky areas by these primates. We suggest that howler and spider monkeys employ behavioral strategies aimed at minimizing the probability of predation while visiting the forest floor at risky mineral lick sites.     

Raiding parties of male spider monkeys: Insights into human warfare?

Raids into neighboring territories may occur for different reasons, including the increase of foraging and mating opportunities directly or indirectly through the killing of neighboring rivals. Lethal raids have been mainly observed in humans and chimpanzees, with raiding males being reported to search purposefully for neighbors. Here we report on the first cases ever witnessed of raiding parties of male spider monkeys, a species expected to show such a behavioral tendency, given its similarity with humans and chimpanzees in critical socio-ecological characteristics, such as fission-fusion social dynamics and male-male bonding. Despite the high degree of arboreality of spider monkeys, all seven witnessed raids involved the males progressing single file on the ground in unusual silence. This is remarkably similar to the behavior of chimpanzees. The circumstances around the raids suggest that factors such as reduced mating opportunities, number of males relative to that in the neighboring community, and the strength of bonds among males could play a role in the timing of such actions. The raids did not appear to be aimed at finding food, whereas there is some indication that they may directly or indirectly increase reproductive opportunities. Although no killing was observed, we cannot exclude the possibility that spider monkey raids may be aimed at harming rivals if a vulnerable individual were encountered. The similarity of spider monkey raids with those of chimpanzees and humans supports the notion that lethal raiding is a convergent response to similar socio-ecological conditions.     

Which senses play a role in nonhuman primate food selection? A comparison between squirrel monkeys and spider monkeys

In order to optimize foraging efficiency and avoid toxicosis, animals must be able to detect, discriminate, and learn about the predictive signals of potential food. Primates are typically regarded as animals that rely mainly on their highly developed visual systems, and little is known about the role that the other senses may play in food selection. It was therefore the aim of the present study to assess which senses are involved in the evaluation of food by two species of New World primates: the squirrel monkey and the spider monkey. To this end, six animals per species were repeatedly presented with both familiar and novel food items, and their behavior was videotaped and analyzed. To obtain a further indication of the relative importance of visual and chemosensory cues, the animals were also presented with familiar food items that were experimentally modified in color, odor, or both color and odor. The results demonstrate that squirrel monkeys and spider monkeys use olfactory, gustatory, and tactile cues in addition to visual information to evaluate novel food, whereas they mainly inspect familiar food items visually prior to consumption. Our findings also show that in both species the use of nonvisual cues decreased rapidly with repeated presentations of novel food, suggesting a fast multimodal learning process. Further, the two species clearly differ in their relative use of nonvisual cues when evaluating novel or modified food, with spider monkeys relying more on olfactory cues than squirrel monkeys, and squirrel monkeys relying more on tactile cues compared to spider monkeys.     

AIDS: A problem of antigen presentation?

Evidence is accumulating that antigen-presenting dendritic cells — both those that activate T cells and those that interact with B cells — may be involved in the development of immunodeficiency during HIV-1 infection.     

Patterns of gastrointestinal parasitism among five sympatric prairie carnivores: are males reservoirs?

Male vertebrates are believed to be disproportionately vulnerable to parasites, but empirical support for this contention is mixed. We tested the hypothesis of higher levels of parasitism in males with the use of counts of gastrointestinal helminths in 5 sympatric mammalian carnivores (American badgers, coyotes, red foxes, raccoons, striped skunks) from central Saskatchewan. Parasite burdens for females and males of each host species were compared with the use of prevalence (percentage of hosts infected), intensity (parasites per infected host), and overdispersion (proportion of heavily infected hosts that were male). Of 30 comparisons (13 each for prevalence and intensity, 4 for overdispersion), male bias was detected 8 times (27%), whereas female bias was detected only once (3%), adding some support to the notion that male mammals are more susceptible to parasitism. However, most of the statistical comparisons we undertook revealed no sexual bias (n=21, 70%), suggesting that differential patterns of infection are not ubiquitous in mammals. Moreover, when detected, the magnitude and direction of bias varied among host species, helminth species, and metrics of infection. We conclude that sympatric and ecologically similar mammal species will not always share the tendency for males to be more susceptible to parasitism, and that studies incorporating multiple parasites and metrics of infection are more likely to detect sex bias.     

Goeldi's monkeys: A primate paradox?

“A primate with the skull of a Callicebus, the mandible and feet of a marmoset and the tail and teeth of Pseudocebus [=Cebus] ….” (Riberio, 1941 as cited in Hershkovitz 1 p. 866). Goeldi's monkeys are the least understood species of platyrrhine. The monkeys' small body size, black coloration, tendency to forage in the low forest understory, and cryptic nature, make them difficult to observe in the wild. Until recently, they had never been the focus of a long‐term field study and as a result, little was known of the monkeys' behavior and ecology. Goeldi's monkeys comprise only one recognized species, Callimico goeldii, and have an unusual suite of anatomical and reproductive traits. These traits have created considerable confusion for taxonomists and physical anthropologists.     

Group size and stability: Why do gibbons and spider monkeys differ?

Gibbons and spider monkeys have similar diets, body size, and locomotor patterns. They are therefore expected to be subject to similar socioecological rules. However their grouping patterns differ. Gibbons live in small stable groups, whereas spider monkey form unstable sub-groups that vary from small to large during different seasons. If similar principles apply to the two species, food abundance should vary more for spider monkeys than for gibbons; food density should be similar for the two species when spider monkey sub-groups are the same size as gibbon groups; and the highest level of food abundance should be higher for spider monkeys than for gibbons. These predictions are upheld for a comparison of particular populations ofHylobates muelleri andAteles geoffroyi.     

Do males matter? The role of males in population dynamics

Models of population dynamics generally neglect the presence of males. While this assumption holds under many circumstances, behavioural ecology increasingly tells us that the presence (or absence) of males may have an impact on female fitness, and hence population sizes. Here we ask the question of whether males matter to population dynamics, operationally defined as a dependency of population growth on the relative density of males. We provide simple models, and evaluate the current empirical evidence for them, that illustrate various mechanisms of such male influence: mate searching behavior, male resource use (including effects of sexual dimorphism), sexual harassment and sexual segregation. In each case, theory predicts that males can have an effect on population densities, and in some extreme cases a positive feedback between an increasingly male-biased sex ratio and female harassment may theoretically even bring about population extinction. The results of this study, and the literature reviewed, show that the males can have a substantial effect on population dynamics, particularly so when human influences result in biased sex ratios.     

Asymmetry in spider orb webs: a result of physical constraints?

A typical feature of most vertical orb webs is that the upper web region is smaller and contains less silk than the lower web region, creating an asymmetrical web. The degree of web asymmetry changes during the spider's development: small juveniles construct more symmetrical webs, but older and larger individuals decrease the upper web region. This implies that weight may control the extent of web asymmetry. Using two species, Argiope keyserlingi and Larinioides sclopetarius, we tested the effect of weight increase on web asymmetry by naturally increasing weight through feeding and by artificially adding lead weights to the abdomen of the spiders. Weight increase (natural or artificial) resulted in more asymmetric webs through a reduction of the upper web region. Added weight may interfere with spiral placement in the upper region, because the spider has to lift its abdomen above the carapace during the process. In the lower region, however, the position of the spider is mostly head up during spiral placement. Therefore, amongst other factors, weight and gravitational forces may be physical constraints during web construction. Copyright 1999 The Association for the Study of Animal Behaviour.     

Do males evaluate female age for precopulatory mate guarding in the two-spotted spider mite?

In the two-spotted spider mite Tetranychus urticae (Acari: Tetranychidae), because only the first mating results in fertilisation, adult males guard quiescent deutonymph females, the stage immediately before adult emergence. Previous studies showed that T. urticae males prefer to guard older rather than younger females. However, as previous experimental designs have included uncertain factors, findings have not always been sufficiently rigorous. Therefore, we reexamined whether T. urticae males discriminate between the females closest to becoming receptive and younger females. One male was introduced onto leaf squares with two differently aged quiescent deutonymph females, with time lags between the females of 3, 6, 12 or 23 h, and whether the older or younger female was guarded was recorded. When the time lags between the females were 3, 6 or 12 h, males showed no preferences. Males preferred older females over younger ones only when the time lag was 23 h. Under non-choice conditions, fewer males guarded the 23-h younger females than other older females, suggesting that the attractiveness of the younger females is weaker than older females. Our results are not fully consistent with previous studies; T. urticae males do not obviously discriminate between females closest to becoming receptive and younger females.     

Estimating sex ratio biases in X-linked disorders: is there an excess of males in families with X-linked ichthyosis?

We derive the conditional probabilities for estimating the sex ratio in families ascertained through affected males for the study of X-linked recessive diseases. These conditional probabilities correct for the fact that the probability that a family will be ascertained increases with the number of males in the family. Data from four published studies for X-linked ichthyosis vulgaris are analyzed, three having an excess of males and one having a highly statistically significant excess of males. It is not known if this difference in the two samples represents a biological difference between the two populations or an unrecognized ascertainment bias.     

Patterns of testicular cytology in men with primary infertility: any change since the Gulf War?

OBJECTIVE: To evaluate the patterns of testicular cytology in men with primary infertility, to compare the morphologic patterns between the periods 1990-1995, immediately after Gulf War II, and 1997-2001 and to determine whether there is a correlation between hormonal profile, testicular volume and morphologic pattern. STUDY DESIGN: Retrospective study of men with primary infertility. History, complete physical examination, hormonal assay and testicular ultrasound were evaluated. A total of 545 patients had samples for testicular cytology obtained from both testes. The patient's consent was obtained in all cases. Smears were interpreted under light microscopy after treatment with Diff-Quik. A total of 104 healthy, fertile subjects were used for comparison of the hormonal profile and testicular volume. RESULTS: The mean (+/- SD) age was 28.66 +/- 4.36 years and duration of marriage 4.4 +/- 4.36 years. There were 11.2% patients with normal cytology, 55.8% with hypospermatogenesis, 28.4% with testicular atrophy, 2.9% with Sertoli cells only and 1.7% with maturation arrest. A significant increase in hypospermatogenesis and decrease in the Sertoli cell-only pattern were noted in 1997-2001 when compared with 1990-1995. The mean left testicular volume was 10.53 +/- 5.51 mL3 in the infertile group vs. 15.2 +/- 4.97 in the fertile group (p < 0.003); right testicular volume was 10.84 +/- 4.77 vs. 15.15 +/- 5.31 (p < 0.003). The hormonal profile revealed higher luteinizing hormone and follicle-stimulating hormone levels in the infertile group vs. control group (8.53 +/- 9.03 and 16.44 +/- 19.243 vs. 6.98 +/- 4.53 and 7.37 +/- 6.63, respectively [p < 0.001]). Free testosterone was higher in the fertile group (39.69 +/- 12.76 vs. 20.28 +/- 8.5 [p < 0.000]). CONCLUSION: The majority of infertile males in our cohort had hypospermatogenesis; testicular atrophy was the next most common disorder. There was no major change in overall absolute numbers since the Gulf War. Testicular cytology by fine needle aspiration is a safe and well-tolerated complementary investigation for unexplained male infertility.     

Unusual injury? Recent injury in normal children and children with suspected non-accidental injury.

Four hundred normal children aged between 2 weeks and 11 years were examined to determine the prevalence and site of recent injury of any type. There was evidence of injury in 37% with a steady increase in prevalence to 60% by the end of the third year of life. Bruising of the hands and feet and of the lower legs was the most frequent type of injury. Head and facial injuries were most common between 18 months and 3 years (17% of children) but were rare at other ages. Injury to the lumbar region was unusual before 5 years but was present in 14% of children of school age. In 84 children of similar age where non-accidental injury was proved or suspected a different pattern of injury was present. Sixty per cent had injuries to the head and face; this increase in prevalence was seen at all ages. These children also had more frequent injuries in the lumbar region, particularly before the age of 5 years.     

Carbapenemases: a problem in waiting?

Carbapenems are stable to most prevalent beta-lactamases, and chromosomal carbapenemases are restricted to Stenotrophomonas maltophilia, to a few Bacteroides fragilis, and to rare pathogens. Nevertheless, an acquired metallo-beta-lactamase called IMP-1 is beginning to emerge in Pseudomonas aeruginosa and Enterobacteriaceae isolates in Japan, and has also been found in isolates from Singapore. Furthermore, IMP-producing Acinetobacter spp. have been identified in Italy and Hong Kong. Recently a second group of acquired metallo-carbapenemases, the VIM types, has been recorded from P. aeruginosa isolates in five Eurasian countries. Weak carbapenemases belonging to molecular class D are emerging in A. baumannii world-wide, with two sub-groups apparent. A few acquired carbapenemases belonging to molecular class A also have been reported. Finally it has also been shown that enzymes with feeble carbapenemase activity (e.g. AmpC types and some SHV enzymes) may confer resistance in exceptionally impermeable strains; counterwise, even potent carbapenemases, such as IMP-1, may only give a small reduction in susceptibility in Enterobacteriaceae that lack permeability lesions. Is the emergence of carbapenemase a problem waiting to happen?     

Can proboscis monkeys be successfully maintained in captivity? A case of swings and roundabouts

Although most western zoos have experienced difficulties in maintaining proboscis monkeys, the Singapore Zoo has managed to sustain a social group of proboscis monkeys housed in a large naturalistic exhibit since 1998. Within 3 years after the monkeys were brought to the zoo, five offspring were produced, all of which survived. Natural forest vegetation from 20 plant species was provided along with a staple diet of about seven different species on a daily basis. The calcium and sodium contents of the plant items consumed by monkeys in the Singapore Zoo were similar to those in the diet of wild proboscis monkeys in Borneo. However, the levels of other minerals, such as iron, magnesium, manganese, potassium, zinc, and phosphorus, were significantly lower in the natural vegetation consumed by the monkeys compared to the wild diet. Food supplements such as primate biscuits, cod liver oil, boiled egg, multivitamins, and mineral syrup further ensured a more balanced diet for the captive monkeys. The data presented here show that zoos can maintain these rare Colobine monkeys successfully by provide them with a natural diet, along with appropriate husbandry and hygiene practices, minimal human interference, and applied nutritional science. The husbandry and nutritional management model presented in this paper could be of use to other institutions around the world. Zoo Biol 23:533–544, 2004. © 2004 Wiley-Liss, Inc.     

Are males with more attractive resources more selective in their mate preferences? A test in a polygynous species

In many polygynous species, males typically direct more intensecourtship toward more fecund females. Here we examined thisbehavior in relation to the attractiveness of a male's resource.We used the territorial polygynous beaugregory damselfish (Stegastesleucostictus) and manipulated the quality of male breeding territorieswith two types of artificial sites. We also investigated variablenatural breeding territories. Previous studies have shown thatthese different breeding sites were of different qualities,as judged by the number of eggs accrued by the defending male.Males on all three types of breeding sites did court females,and males using the highest quality sites exhibited significantlyhigher courtship intensity. However, only the group of maleson the highest quality site-type modulated their courtship intensityto female quality (i.e., female size). This indicates that males requiredsome minimal level of resource attractiveness (i.e., a threshold) beforethey exhibited mate preferences based on female quality. Further differencesin the resource attractiveness for males defending the high-qualityartificial sites were not related to differences in courtship behavior.