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Franceschini, C., Siutz, C., Palme, R., & Millesi, E. (2007). Seasonal changes in cortisol and progesterone secretion in Common hamsters. Gen Comp Endocrinol, 152(1), 14–21.
Abstract: In this study, we investigated endocrine factors and behaviour in free-living Common hamsters (Cricetus cricetus) during reproductive and non-reproductive periods of the annual cycle. We applied a non-invasive method to gain information on seasonal changes in adrenocortical activity in male and female hamsters by analysing faecal glucocorticoid metabolite concentrations (FCM). In addition, plasma progesterone concentrations were monitored in females throughout the non-hibernation season. The animals were live-trapped from spring emergence until the onset of hibernation in autumn. Reproductive status was determined at capture and blood and faecal samples were collected. During behavioural observations, agonistic and sexual interactions were recorded. FCM concentrations were significantly higher in males than in females during the reproductive period. In males, a pronounced increase in FCM during the reproductive period coincided with high frequencies of intrasexual aggression. In females, FCM levels remained relatively constant. Aggressive behaviour in females increased during the reproductive period, but was much less frequent than in males. Females, which successfully raised a second litter after a postpartum oestrus and concurrent lactation and gestation had lower FCM levels than individuals, which lost their second litter after parturition. As expected, plasma progesterone concentrations were low before and after the reproductive period. During gestation, levels peaked and remained elevated during lactation. The results of this field study provide insight in critical periods associated with reproduction in male and female Common hamsters.
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Li, C., Jiang, Z., Tang, S., & Zeng, Y. (2007). Influence of enclosure size and animal density on fecal cortisol concentration and aggression in Pere David's deer stags. Gen Comp Endocrinol, 151(2), 202–209.
Abstract: We investigated the impact of enclosure size and animal density on behavior and adrenocortical secretion in Pere David's deer in Dafeng Nature Reserve, China. From February 15 to April 16 in 2004, we conducted two experiments. First, we studied maintenance behavior and conflict behavior of Pere David's deer stags in a large enclosure (200 ha) with low animal density (0.66 deer/ha) and a small display pen (0.75 ha) with high animal density (25.33 deer/ha). The maintenance behavior we recorded included standing, locomotion, foraging and rest. During the behavioral observations, we collected fresh voided fecal samples from the stags periodically, and analyzed the fecal cortisol concentrations in those samples using radioimmunoassay technique. Second, we monitored the fecal cortisol concentrations of one group of stags (12 deer lived in an enclosure of 100 ha) before and after transferred into a small pen (0.5 ha). We found that in the first experiment: (1) there were significant differences in standing and rest whereas no significant differences of locomotion and foraging between the free-ranging group and the display group; (2) frequency of conflict behavior in the display group was significantly higher than those in the free-ranging group; and (3) fecal cortisol concentration of the display group (326.17+/-16.98 ng/g dry feces) was significantly higher than that of the free-ranging group (268.98+/-15.21 ng/g dry feces). In the second experiment, there was no significant difference of the fecal cortisol concentrations among sampling days, but the mean fecal cortisol concentration of the day after transferring (337.46+/-17.88 ng/g dry feces) was significantly higher than that of the day before transferring (248.44+/-7.99 ng/g dry feces). Comparison with published findings, our results indicated that enclosure size and animal density affect not only behaviors, but also adrenocortical secretion in Pere David's deer. Small living space with high animal density may impose physiological stress to captive Pere David's deer. Moreover, long-term physiological stress and increase of conflict behavior may subsequently affect survival and reproduction of the deer.
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Petter-Puchner, A. H., Froetscher, W., Krametter-Froetscher, R., Lorinson, D., Redl, H., & van Griensven, M. (2007). The long-term neurocompatibility of human fibrin sealant and equine collagen as biomatrices in experimental spinal cord injury. Exp Toxicol Pathol, 58(4), 237–245.
Abstract: INTRODUCTION: While fibrin sealant (FS) and equine collagen (EC) have been used as scaffold materials in experimental spinal cord injury (SCI), questions concerning neurocompatibility still remain. In this study, we assessed potential adverse effects, as well as functional and histological impact of FS and EC in subtotal hemisection of the thoracic spinal cord (SC) in rats. METHODS: 124 male rats were randomly assigned to four main groups (n=31): Sham (SH), Lesion only (L), fibrin sealant (GFS) and equine collagen group (GEC). SH animals received laminectomy only; all other animals underwent subtotal lateral hemisection at T9. Treatment consisted of application of FS or EC into the lesion gap in GFS and GEC, which was left empty in L. GFS, GEC, L and SH were each further divided into 4 subgroups: One subgroup, consisting of 10 rats was subjected to behavioural and reflex testing before surgery and followed up on days 1,7, 14, 21, 28 post op and then sacrificed. Haemalaun or cresyl violet (CV) was used to identify neutrophils in parasagittal cord sections which were obtained on day 1 (n=7). Sections stained for quantification of microglia/macrophages using ED-1 on day 3 (n=7), day 7 (n=7) and day 28 (n=7 out of 10). Additionally, neural filament (NF) staining was chosen to detect axonal regeneration and the length of ingrowth into FS and EC, Luxol blue for myelination, Von Willebrand factor for vascularisation, and glial fibrillary acidic protein (GFAP) staining for detection of astrocytes in glial scars on day 28. RESULTS: No adverse effects were observed in the treatment groups. Compared to L, GFS and GEC performed significantly better in the Basso, Beattie, Bresnahan (BBB) score and hopping responses. Proprioceptive placing was markedly improved in FS and EC compared to L. Axonal regrowth was found in GFS and GEC--the regrowth in the GFS was accompanied by myelination and vascularisation. Glial scarring occurred in all groups. Discussion Both biomatrices improved functional recovery compared to L and no adverse effects were perceived.
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Lusseau, D. (2007). Evidence for social role in a dolphin social network. Evol. Ecol., 21(3), 357–366.
Abstract: Abstract Social animals have to take into consideration the behaviour of conspecifics when making decisions to go by their daily lives. These decisions affect their fitness and there is therefore an evolutionary pressure to try making the right choices. In many instances individuals will make their own choices and the behaviour of the group will be a democratic integration of everyone’s decision. However, in some instances it can be advantageous to follow the choice of a few individuals in the group if they have more information regarding the situation that has arisen. Here I provide early evidence that decisions about shifts in activity states in a population of bottlenose dolphin follow such a decision-making process. This unshared consensus is mediated by a non-vocal signal, which can be communicated globally within the dolphin school. These signals are emitted by individuals that tend to have more information about the behaviour of potential competitors because of their position in the social network. I hypothesise that this decision-making process emerged from the social structure of the population and the need to maintain mixed-sex schools.
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Pérez-Barbería, F. J., Shultz, S., Dunbar, R. I. M., & Janis, C. (2007). Evidence For Coevolution Of Sociality And Relative Brain Size In Three Orders Of Mammals. Evolution, 61(12), 2811–2821.
Abstract: Abstract
As the brain is responsible for managing an individual's behavioral response to its environment, we should expect that large relative brain size is an evolutionary response to cognitively challenging behaviors. The “social brain hypothesis” argues that maintaining group cohesion is cognitively demanding as individuals living in groups need to be able to resolve conflicts that impact on their ability to meet resource requirements. If sociality does impose cognitive demands, we expect changes in relative brain size and sociality to be coupled over evolutionary time. In this study, we analyze data on sociality and relative brain size for 206 species of ungulates, carnivores, and primates and provide, for the first time, evidence that changes in sociality and relative brain size are closely correlated over evolutionary time for all three mammalian orders. This suggests a process of coevolution and provides support for the social brain theory. However, differences between taxonomic orders in the stability of the transition between small-brained/nonsocial and large-brained/social imply that, although sociality is cognitively demanding, sociality and relative brain size can become decoupled in some cases. Carnivores seem to have been especially prone to this.
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Pérez-Barbería, F. J., Shultz, S., & Dunbar, R. I. (2007). Evidence for coevolution of sociality and relative brain size in three orders of mammals. Evolution, 61.
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Jellinger, K. A. (2007). Comparative Cognition: Experimental Exploration of Animal Intelligence. European Journal of Neurology, 14, e53.
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Ceacero, F., Landete-Castillejos, T., Garcia, A. J., Estevez, J. A., & Gallego, L. (2007). Kinship Discrimination and Effects on Social Rank and Aggressiveness Levels in Iberian Red Deer Hinds. Ethology, 113(12), 1133–1140.
Abstract: Abstract Kin recognition is a widespread phenomenon that allows individuals to benefit by enhancing their inclusive fitness, and one of its most common forms is reducing aggressiveness towards relatives. We carried out an experiment with Iberian red deer hinds (Cervus elaphus hispanicus) in order to examine kin biases in dominance behaviour and its consequences on social rank. Three enclosed groups (n = 36, 23 and 21, respectively) were monitored during two lactation seasons and social rank hierarchies were assessed by analysing aggressive interactions matrices with Matman 1.1 software. Aggressive interactions between related hinds was significantly smaller than expected (chi2 = 5.02, df = 1, p = 0.025), not only between mother and daughter but also in second and third kinship degrees. Although rates of aggressiveness were similar to data published relating free-ranging C. e. scoticus, aggressive interactions with relatives were significantly smaller (chi2 = 39.0, df = 1, p < 0.001). This reduction of aggressiveness between related hinds was not the result of these hinds having a lower social rank: social rank was only related to age and weight, but not to kinship degree, calf sex or calving date. The decrease of aggressiveness towards first-, second- and third-degree relatives shows a complex kin recognition system in deer. Possible nepotistic roles in lactation include preventing milk thefts by non-kin and disturbing feeding of unrelated hinds.
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Pannozzo, P. L., Phillips, K. A., Haas, M. E., & Mintz, E. M. (2007). Social Monitoring Reflects Dominance Relationships in a Small Captive Group of Brown Capuchin Monkeys (Cebus apella). Ethology, 113(9), 881–888.
Abstract: Abstract In several studies of social monitoring in primates, subordinate animals directed more visual attention toward dominant animals than vice versa. This behavior is thought to enable subordinate animals to avoid conflict. We sought to clarify whether visual attention behavior functions in this manner in a small captive group of brown capuchin monkeys, Cebus apella. We tested the hypothesis that social monitoring is related to dominance status. Dominance status was determined based on the directionality of aggressive behavior, and visual attention was quantified by using focal animal sampling. Subordinate animals directed significantly more visual attention toward others than dominant animals. Subordinate animals also looked more frequently at the animals that attacked them and others the most. The results indicate that social monitoring behavior in this captive group was driven by conflict-avoidance.
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Mills, D. S. (2007). Comments about the importance of behaviour to equine clinicians. Equine Vet J, 39(1), 95.
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