Female emancipation in a male dominant, sexually dimorphic primate under natural conditions

In most group-living animals, a dominance hierarchy reduces the costs of competition for limited resources. Dominance ranks may reflect prior attributes, such as body size, related to fighting ability or reflect the history of self-reinforcing effects of winning and losing a conflict (the winner-loser effect), or both. As to prior attributes, in sexually dimorphic species, where males are larger than females, males are assumed to be dominant over females. As to the winner-loser effect, the computational model DomWorld has shown that despite the female’s lower initial fighting ability, females achieve some degree of dominance of females over males. In the model, this degree of female dominance increases with the proportion of males in a group. This increase was supposed to emerge from the higher fraction of fights of males among themselves. These correlations were confirmed in despotic macaques, vervet monkeys, and in humans. Here, we first investigate this hypothesis in DomWorld and next in long-term data of 9,300 observation hours on six wild groups of robust capuchin monkeys (Sapajus libidinosus; S. nigritus, and S. xanthosternos) in three Brazilian sites. We test whether both the proportion of males and degree of female dominance over males are indeed associated with a higher relative frequency of aggression among males and a higher relative frequency of aggression of females to males. We confirm these correlations in DomWorld. Next, we confirm in empirical data of capuchin monkeys that with the proportion of males in the group there is indeed an increase in female dominance over males, and in the relative frequency of both male-male aggression and aggression of females to males and that the female dominance index is significantly positively associated with male male aggression. Our results reveal that adult sex ratio influences the power relation between the sexes beyond predictions from socioecological models.</p

Measures of cortisol metabolites in capuchin monkeys (Sapajus genus): a comparative analysis between wild populations to investigate stressors

Estudos da fisiologia do estresse são de fundamental importância para a área de endocrinologia comportamental e para projetos visando à promoção do bem estar de animais cativos. Esses estudos, quando feitos com animais de vida-livre, possibilitam investigar quais estímulos ambientais ou sociais são estressores para o táxon estudado. Pouco se sabe a este respeito sobre macacos-prego (gênero Sapajus), um primata neotropical muito comum em zoológicos, criadouros e outras situações de cativeiro. Uma maior compreensão dos agentes estressores neste gênero pode contribuir para o bem estar de sujeitos cativos. Frente a isso, este trabalho objetivou: 1) investigar, a partir da variação dos níveis de glicocorticóides (GCs; hormônios ligados ao estresse), quais eventos ambientais e comportamentais são percebidos por macacos-prego selvagens como estressantes; 2) verificar a possibilidade de definir valores de referência de níveis aceitáveis (nível basal) de metabólitos fecais de glicocorticóides (MFGs a mensuração de GCs a partir de fezes permite avaliar estes hormônios de forma não-invasiva) para o gênero Sapajus; e 3) validar o protocolo experimental de extração e dosagem de hormônios fecais. Em relação aos dois primeiros objetivos, foram tomadas medidas de metabólitos fecais de glicocorticóides, e de dados ambientais e comportamentais de duas populações selvagens, uma do Parque Estadual Carlos Botelho/São Paulo (PECB) e outra da Fazenda Boa Vista/Piauí (FBV). Para a validação do protocolo experimental, foi realizado um desafio de ACTH e dexametasona com macacos-prego cativos. Análises por modelo linear generalizado misto (MLGM) mostraram diferença significativa entre os níveis basais de MFGs das duas populações estudadas, sendo maiores na população da FBV. Para esta população, foi encontrado efeito de oferta de frutos no habitat, de freqüência de encontros com outras espécies animais e de cópulas, sobre a variação mensal dos níveis basais de MFGs. Para a população do PECB, nenhuma das variáveis estudadas apresentou efeito significativo sobre a variação mensal dos níveis basais de MFGs. Já as análises individuais mostraram que interações agonísticas entre membros do grupo foram os maiores causadores de picos de MFGs nos sujeitos estudados, seguidos por fêmeas em período proceptivo e cópulas, que causaram picos não só em machos adultos, mas também em machos juvenis e nas próprias fêmeas. Os resultados do desafio de ACTH e de dexametasona validaram o protocolo experimental de extração e dosagem hormonal. Os resultados obtidos estão de acordo com pesquisas anteriores que revelaram diferenças marcantes no sistema social das duas populações, especialmente no que se refere às relações sociais de fêmeas, de acordo com as diferenças ecológicas entre as duas áreas. Além disso, sugerem que não é possível definir valores de referência de nível basal de MFGs para o gênero Sapajus, já que as duas populações diferem significativamente quanto a este aspecto. A partir deste trabalho, que é apenas o começo de uma longa jornada para a compreensão do estresse em macacos-prego selvagens, começa-se a entender quais são os estressores naturais destes animais e como eles impactam os níveis de MFGsStress physiology studies are of fundamental importance for the area of behavioral endocrinology and for projects that aim to promote the wellbeing of captive animals. When the subjects of those researches are wild animals, it is possible to investigate which environmental or social stimuli constitute stressors for this taxon. Little is known in this regard about capuchin monkeys (Sapajus genus), a neotropical primate that are constantly kept in zoos, breeders and others captive environments. A better comprehension of the stressors agents in this genus can contribute for the wellbeing of those captive individuals. Therefore this study aimed: 1) to investigate through the variation of glucocorticoids levels (GCs hormones related to stress), which environmental and behavioral events are perceived by wild capuchin monkeys as stressful; 2) access the possibility of defining basal fecal glucocorticoids metabolites levels (MFGs measuring GCs in feces is a non-invasive form of evaluate those hormones), as reference values, for the Sapajus genus; and 3) validate the experimental protocol of fecal hormones extraction and dosage. For the first two objectives, measures of fecal glucocorticoids metabolites, behavioral and environmental data of two wild populations of capuchin monkeys were taken. One in the Carlos Botelho State Park/São Paulo (PECB) and the other in Boa Vistas Farm/Piauí (FBV). For the experimental protocol validation an ACTH and dexamethasone challenge was executed with captive capuchin monkeys. Generalized Linear Mixed Models (MLGM) analysis showed a significant difference between basal levels of MFGs of the two populations, being the FBV the one with higher values. For that population there was also an effect of fruit availability in the habitat, frequency of encounters with other animals species and copulations in the mensal variation of the MFGs basal levels. There was no significant effect of the studied variables in the mensal basal levels variation of MFGs in the PECB population. The individual analyses showed that agonistic interactions among group members were the major cause of MFGs\' peaks in the studied subjects. Other major factors were females in proceptive period and copulations, that caused peaks not only in adult males, but also in juvenile males and the females themselves. The ACTH and dexamethasone challenge results validated the experimental protocol of hormones extraction and dosage. The obtained results are in agreement with previous researches that reveled marked differences in the social system of the two populations, specially in females social relationships that varied in accordance with the two areas ecological differences. The results also suggested that it is not possible to define reference values of MFGs\' basal levels for the Sapajus genus once the two populations are significantly different in this aspect. This work is just the beginning of a long endeavor to comprehend stress in wild capuchin monkeys, nevertheless it presents the first glimpse to the understanding of the natural stressors for those animals and how they impact the MFGs\' level

Tool use as environmental enrichment for captives capuchin monkeys (Cebus apella)

Manter animais em cativeiro implica no dever ético de lhes proporcionar saúde física e psicológica. Procedimentos conhecidos como Enriquecimento Ambiental buscam elevar o bem-estar de animais cativos. Neste trabalho, três artefatos foram testados para avaliar sua eficácia como enriquecimento ambiental para macacos-prego (Cebus apella). Dois destes artefatos (Brinquedo e Caixa de forrageamento) já haviam sido testados anteriormente por Boinski et al. (1999). O terceiro artefato (Ferramenta) foi testado pela primeira vez e buscava proporcionar aos animais a possibilidade de executar um comportamento típico da espécie: a quebra de cocos. Usamos medidas comportamentais e de corticosterona fecal para medir os efeitos dos artefatos. Foram encontradas algumas diferenças significativas entre as condições experimentais (controles e com artefatos), e entre a freqüência de interação com os artefatos, porém os resultados não nos possibilitam afirmar se algum dos artefatos seria um enriquecimento ambiental eficaz para macacos-prego cativos. Acreditamos que experimentos ainda devem ser feitos para elucidar os efeito de fatores como: o ambiente externo ao recinto, os procedimentos de manutenção direcionados aos animais e a metodologia de aplicação dos artefatos, sobre o bem-estar de animais cativos.Keeping animals in captivity implies in an ethical duty of offering conditions that foster their physical and psychological health. Procedures known as Environmental Enrichment seek to enhance animals life quality. Here we tested three stimuli efficiency as environmental enrichment for captive capuchin monkeys (Cebus apella). Two which had been previously tested (Toy and Box) by Boinski et al. (1999). The third one (Tool) was tested for the first time and aimed giving the animals the opportunity to perform a species-typical behavior: cracking open nuts. The stimuli had their effects measured by behavioral and fecal corticosterone sampling. Some statistical significant differences were found between experimental conditions (control and stimuli) and between the frequencies of interaction with the stimuli. The data, however, did not point to any of the tested stimuli as effective environmental enrichment for capuchin monkeys. We believe, therefore, that more research should be conducted in order to clarify the effects of factors such as the environment outside the cages, the maintenance procedures, and the stimulus presentation procedures, on the well-being of captive animals

Learning generalization in problem solving by a blue-fronted parrot (Amazona aestiva)

Pepperberg (The Alex studies: cognitive and communicative abilities of gray parrots. Harvard University Press, Cambridge;1999) showed that some of the complex cognitive capabilities found in primates are also present in psittacine birds. Through the replication of an experiment performed with cotton-top tamarins (Saguinus oedipus oedipus) by Hauser et al. (Anim Behav 57:565-582; 1999), we examined a blue-fronted parrot`s (Amazona aestiva) ability to generalize the solution of a particular problem in new but similar cases. Our results show that, at least when it comes to solving this particular problem, our parrot subject exhibited learning generalization capabilities resembling the tamarins`.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)CNPq (Conselho Nacional de Desenvolvimento Cientifico e Tecnologico

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved