Experimental provisioning increases play in free-ranging meerkats

The sensitivity of play to variations in food availability has been cited as evidence of the costliness of play, since energetically stressed animals dispense with costly behaviours. However, the causality of the relationship between nutrition and play has not been adequately tested. Using weight gain as a measure of food intake, we documented the food consumption of free-ranging meerkat, Suricata suricatta, pups and found that long-term nutritional status (weight gain over a 6-week period) was positively correlated with rates of play. We confirmed the causality of this relationship by conducting long-term (4-8 weeks) provisioning experiments that raised the nutritional status of experimental pups, subadults and adults. Experimental animals more than doubled their rate of play compared with their nonprovisioned controls. Short-term variations in food consumption (daily weight gain) were not correlated with subsequent rates of play, and we used a short-term feeding experiment to document the transitory effects of hunger satiation. We established that an increase in available energy contributed to the increase in rates of play, rather than the animals simply having more time available to play as a result of being released from the constraints of foraging. We conclude that play in meerkats was energetically costly, and must be adaptive given that the cost of play to juveniles (in terms of future reproductive success) was potentially high. Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved.     

Radiocollars do not affect the survival or foraging behaviour of wild meerkats

The practice of radiocollaring is increasingly being used in the study of wild animal populations. However, methods of tracking and monitoring are known to affect some species negatively. On a wild population of habituated meerkats Suricata suricatta , we investigated the potential costs and consequences of carrying a radiocollar for small carnivores, focusing on detailed aspects of foraging behaviour and survival. Radiocollared individuals were no more likely to be predated than non-collared individuals in the same social group. We also found that collaring did not affect foraging efficiency, with collared individuals being equally efficient foragers (four measures) while wearing a collar compared with the pre-collaring period. To control for group-specific events, changes in foraging efficiency after collaring were compared with the behaviour of control individuals from the same group and no significant differences were found. In conclusion, we found no evidence to suggest radiocollars impact negatively on the bearer's welfare, survival or foraging ability.     

Maternal investment during pregnancy in wild meerkats

Maternal investment in offspring development is a major determinant of the survival and future reproductive success of both the mother and her young. Mothers might therefore be expected to adjust their investment according to ecological conditions in order to maximise their lifetime fitness. In cooperatively breeding species, where helpers assist breeders with offspring care, the size of the group may also influence maternal investment strategies because the costs of reproduction are shared between breeders and helpers. Here, we use longitudinal records of body mass and life history traits from a wild population of meerkats (Suricata suricatta) to explore the pattern of growth in pregnant females and investigate how the rate of growth varies with characteristics of the litter, environmental conditions, maternal traits and group size. Gestational growth was slight during the first half of pregnancy but was marked and linear from the midpoint of gestation until birth. The rate of gestational growth in the second half of pregnancy increased with litter size, maternal age and body mass, and was higher for litters conceived during the peak of the breeding season when it is hot and wet. Gestational growth rate was lower in larger groups, especially when litter size was small. These results suggest that there are ecological and physiological constraints on gestational growth in meerkats, and that females may also be able to strategically adjust their prenatal investment in offspring according to the likely fitness costs and benefits of a particular breeding attempt. Mothers in larger groups may benefit from reducing their investment because having more helpers might allow them to lower reproductive costs without decreasing breeding success.     

Social facilitation does not reduce neophobia in Chestnut-sided Warblers (Parulinae:Dendroica pensylvanica)

Chestnut-sided Warblers (Dendroica pensylvanica) show aversion to feeding at a familiar food source if placed next to a novel object. I have suggested that neophobia is an adaptation of specialized animals to reduce wasteful exploration. In this experiment I tested whether social facilitation mitigates the fear and decreases the latency to forage at a novel foraging site. As far as I know, the effect of social factors on neophobia has not been previously investigated. Because Chestnut-sided Warblers are intraspecifically solitary during the non-breeding season, I examined their response to novel foraging sites in the presence of a Bay-breasted Warbler (D. castanea) “trainer”. Chestnut-sided Warblers commonly join flocks with this more generalized and less neophobic congener. Chestnut-sided Warblers showed no tendency to feed in the presence of a Bay-breasted Warbler that is freely feeding from the unfamiliar microhabitat. Specialized animals may be more resistant to social facilitation and observational learning than more generalized species.     

Social play in wild brown bears of varying age-sex class

Social play behaviour is a well-described phenomenon, almost ubiquitous among mammals. Despite its prevalence, social play takes several forms and may vary in function across species. For solitary species, the function of play outside of the family group remains unclear. Here, we describe the motor patterns of play among non-littermate wild brown bears Ursus arctos of different age-sex class. Play was documented during a time of abundant food availability in three different scenarios: play among non-littermate subadults, play among non-littermate cubs, and play among a ‘group’ of bears of different age and sex class. We used a previously described behavioural ethogram to recognise play. Play followed typical motor patterns and postures expressed by bears during play-fighting: relaxed face, puckered-lip, ears partially flattened to crescent, wrestling, jaw gaping, play-biting, paw-swatting, and lunging. No vocalisations were conducted during play bouts. Older bears displayed ‘self-handicapping’ and ‘role-reversal’ in the play postures they selected when playing with younger bears, suggesting that tactics vary according to age class and dominance ranking. Playing likely allows for the evaluation of conspecifics in a non-aggressive way during times of reduced competition and could also relieve stress in complex social situations.     

Social monitoring via close calls in meerkats

Social monitoring of the actions of group members is thought to be a key development associated with group living. Humans constantly monitor the behaviour of others and respond to them in a flexible way depending on past interactions and the current social context. While other primates have also been reported to change their behaviour towards other group members flexibly based on the current state of their relationship, empirical evidence is typically linked to contextually specific events such as aggressive or reproductive interactions. In the cooperatively breeding meerkat (Suricata suricatta), we investigated whether subordinate females use frequently emitted, non-agonistic close calls to monitor the location of the dominant female and whether they subsequently adjust their response based on recent social interactions during conflict and non-conflict periods. Subjects discriminated between the close calls of the dominant female and control playbacks, responding by approaching the loudspeaker and displaying submissive behaviour only if they were currently threatened by eviction. Our results suggest that meerkats assess the risk for aggressive interactions with close associates depending on social circumstances, and respond accordingly. We argue that social monitoring based on non-agonistic cues is probably a common mechanism in group-living species that allows the adjustment of behaviour depending on variation in relationships.     

Halofuginone does not reduce fibrosis in bleomycin-induced lung injury

Halofuginone, a coccidiostatic alkaloid, has anti-fibrotic properties, and may be useful as a therapeutic agent in lung fibrosis. To test this hypothesis we investigated the effect of halofuginone on bleomycin-induced lung fibrosis in Sprague-Dawley rats. Treatment groups included: (1) a single intratracheal (IT) instillation of 1.2U bleomycin, and intraperitoneal (IP) injection of halofuginone (0.5 mg/dose), every other day; (2) IT 1.2U bleomycin and IP distilled water (D.W.), every other day; (3) IT 0.8U bleomycin and daily IP halofuginone (0.5 mg/dose); (4) IT 0.8U bleomycin and daily IP D.W.; (5) IT saline and IP halofuginone, every other day; (6) IT saline and daily IP D.W.; (7) IT 0.625U bleomycin and oral halofuginone (10 mg/kg rodent lab chow); (8) IT 0.625U bleomycin and standard lab chow. Animals were studied 14 days after IT instillation. Lung injury was evaluated by total and differential cell count in bronchoalveolar lavage fluid, by a semi-quantitative morphological index of lung injury, and by biochemical analysis of lung hydroxyproline content. Overt signs of lung injury were apparent in bleomycin-treated rats by all measures. These changes were not affected by treatment with halofuginone, irrespective of the treatment regimen used. This study does not support the use of halofuginone to prevent or ameliorate lung fibrosis.     

Intragametophytic selfing does not reduce reproduction inDryopteris filix-max

Gametophytes ofDryopteries filix-mas (L.) Schott were grown as isolates and as pairs of related and unrelated individuals. Reproductive efforts were generally highest among isolates, which reproduce by intragametophytic selfing only. Reproductive success ofD. filixmas may depend on the abundance of resources rather than the actual mating system employed. The estimates of the amount of genetic load for the two populations examined were low, 10% and 16%, respectively. The great numbers and the high viability of sporophytes produced by intragametophytic selfing indicate thatD. filix-mas does not experience serious inbreeding depression.     

A simple test of vocal individual recognition in wild meerkats

Individual recognition is thought to be a crucial ability facilitating the evolution of animal societies. Given its central importance, much research has addressed the extent of this capacity across the animal kingdom. Recognition of individuals vocally has received particular attention due, in part, to the insights it provides regarding the cognitive processes that underlie this skill. While much work has focused on vocal individual recognition in primates, there is currently very little data showing comparable skills in non-primate mammals under natural conditions. This may be because non-primate mammal societies do not provide obvious contexts in which vocal individual recognition can be rigorously tested. We addressed this gap in understanding by designing an experimental paradigm to test for individual recognition in meerkats (Suricata suricatta) without having to rely on naturally occurring social contexts. Results suggest that when confronted with a physically impossible scenario-the presence of the same conspecific meerkat in two different places-subjects responded more strongly than during the control, a physically possible setup. We argue that this provides the first clear evidence for vocal individual recognition in wild non-primate mammals and hope that this novel experimental design will allow more systematic cross-species comparisons of individual recognition under natural settings.