Laure Cauchard

Problem-solving performance is correlated with reproductive success in a wild bird population

Although interindividual variation in problem-solving ability is well documented, its relation to variation in fitness in the wild remains unclear. We investigated the relationship between performance on a problem-solving task and measures of reproductive success in a wild population of great tits, Parus major. We presented breeding pairs during the nestling provisioning period with a novel string-pulling task requiring the parents to remove an obstacle with their leg that temporarily blocked access to their nestbox. We found that nests where at least one parent solved the task had higher nestling survival until fledging than nests where both parents were nonsolvers. Furthermore, clutch size, hatching success and fledgling number were positively correlated with speed in solving the task. Our study suggests that natural selection may directly act on interindividual variation in problem-solving performance. In light of these results, the mechanisms maintaining between-individual variation in problem-solving performance in natural populations need further investigation.

Innovation in groups: does the proximity of others facilitate or inhibit performance?

Summary Foraging innovation, in which an individual eats a novel food or uses a novel foraging technique, has been observed in a wide range of species. If other individuals are nearby, they may adopt the innovation, thus spreading it through the population. Much research has focused on this social transmission of behaviour, but the effect of social context on the emergence of novel behaviour is unclear. Here, we examine the effect of social context on innovative feeding behaviour in the Carib grackle (Quiscalus lugubris), an opportunistic, gregarious bird. We test the effect of the proximity of conspecifics, while eliminating the direct effects of interference, scrounging, or aggression. Using a repeated-measures design, we found that birds took significantly longer to contact novel foraging tasks when in the presence of others vs. alone, and during playbacks of alarm calls vs. a control sound. Further, performance of a food-processing behaviour decreased when birds were with others, and individuals adjusted their behaviour depending on their distance from conspecifics. Our results suggest that feeding in groups may slow down or inhibit innovative foraging behaviour in this species. We discuss the implications of a trade-off between feeding in groups and taking advantage of new feeding opportunities.

The repeatability of cognitive performance: a meta-analysis

Behavioural and cognitive processes play important roles in mediating an individuals interactions with its environment. Yet, while there is a vast literature on repeatable individual differences in behaviour, relatively little is known about the repeatability of cognitive performance. To further our understanding of the evolution of cognition, we gathered 44 studies on individual performance of 25 species across six animal classes and used meta-analysis to assess whether cognitive performance is repeatable. We compared repeatability (R) in performance (1) on the same task presented at different times (temporal repeatability), and (2) on different tasks that measured the same putative cognitive ability (contextual repeatability). We also addressed whether R estimates were influenced by seven extrinsic factors (moderators): type of cognitive performance measurement, type of cognitive task, delay between tests, origin of the subjects, experimental context, taxonomic class and publication status. We found support for both temporal and contextual repeatability of cognitive performance, with mean R estimates ranging between 0.15 and 0.28. Repeatability estimates were mostly influenced by the type of cognitive performance measures and publication status. Our findings highlight the widespread occurrence of consistent inter-individual variation in cognition across a range of taxa which, like behaviour, may be associated with fitness outcomes. This article is part of the theme issue ‘Causes and consequences of individual differences in cognitive abilities’.

Selective disappearance of individuals with high levels of glycated haemoglobin in a free-living bird.

Although disruption of glucose homeostasis is a hallmark of ageing in humans and laboratory model organisms, we have little information on the importance of this process in free-living animals. Poor control of blood glucose levels leads to irreversible protein glycation. Hence, levels of protein glycation are hypothesized to increase with age and to be associated with a decline in survival. We tested these predictions by measuring blood glycated haemoglobin in 274 adult collared flycatchers of known age and estimating individual probability of recapture in the following 2 years. Results show a strong decrease in glycated haemoglobin from age 1 to 5 years and an increase thereafter. Individuals with high levels of glycated haemoglobin had a lower probability of recapture, even after controlling for effects of age and dispersal. Altogether, our findings suggest that poor control of glucose homoeostasis is associated with lower survival in this free-living bird population, and that the selective disappearance of individuals with the highest glycation levels could account for the counterintuitive age-related decline in glycated haemoglobin in the early age categories.

Effect of an anti-malaria drug on behavioural performance on a problem-solving task: an experiment in wild great tits.

Malaria parasites have been shown to decrease host fitness in several species in the wild and their detrimental effects on host cognitive ability are well established in humans. However, experimental demonstrations of detrimental effects on non-human host behaviour are currently limited. In this study, we experimentally tested whether injections of an anti-malaria drug affected short-term behavioural responses to a problem-solving task during breeding in a wild population of great tits (Parus major) naturally infected with malaria. Adult females treated against malaria were more active than control females, even though they were not more likely to solve the task or learn how to do so, suggesting that energetic constraints could shape differences in some behaviours while changes in cognitive performances might require more time for the neural system to recover or may depend mainly on infection at the developmental stage. Alternatively, parasite load might be a consequence, rather than a cause, of inter-individual variation in cognitive performance. These results also suggest that inter-individual as well as inter-population differences in some behavioural traits may be linked to blood parasite load.

Divergence in problem-solving skills is associated with differential expression of glutamate receptors in wild finches

Wild birds that vary in their problem-solving capacity were found to express different neurotransmitter receptor densities. Problem solving and innovation are key components of intelligence. We compare wild-caught individuals from two species that are close relatives of Darwin’s finches, the innovative Loxigilla barbadensis, and its most closely related species in Barbados, the conservative Tiaris bicolor. We found an all-or-none difference in the problem-solving capacity of the two species. Brain RNA sequencing analyses revealed interspecific differences in genes related to neuronal and synaptic plasticity in the intrapallial neural populations (mesopallium and nidopallium), especially in the nidopallium caudolaterale, a structure functionally analogous to the mammalian prefrontal cortex. At a finer scale, we discovered robust differences in glutamate receptor expression between the species. In particular, the GRIN2B/GRIN2A ratio, known to correlate with synaptic plasticity, was higher in the innovative L. barbadensis. These findings suggest that divergence in avian intelligence is associated with similar neuronal mechanisms to that of mammals, including humans.

An experimental test of a causal link between problem-solving performance and reproductive success in wild great tits

Recent studies have uncovered relationships between measures of various cognitive performances and proxies of fitness such as reproductive success in non-human animals. However, to better understand the evolution of cognition in the wild, we still have to determine the causality of these relationships and the underlying mechanisms. The cognitive ability of an individual may directly influence its ability to raise many and/or high quality young through for example its provisioning ability. Conversely, large and/or high quality broods may lead to high parental motivation to solve problems related to their care. To answer this question, we manipulated reproductive success through brood size and measured subsequent problem-solving performance in wild great tit parents. Our results show that brood size manipulation did not affect the probability to solve the task. Moreover, solver pairs fledged more young than non-solver pairs independently of brood size treatment in one of the two experimental years and they showed higher nestling provisioning rate in both years. Overall, it shows that problem-solving performance was not driven by motivation and suggest that problem-solvers may achieve higher fledging success through higher provisioning rates. Our study constitutes a first key step towards a mechanistic understanding of the consequences of innovation ability for individual fitness in the wild.

House Sparrows (Passer domesticus) Use Cars to Shelter

ABSTRACT During winter 2015 in Montreal (Canada), we observed on two occasions a group of House Sparrows (Passer domesticus) hiding under the body of several cars, in the empty spaces between the wheels and the fender. On both occasions, it was either snowing or raining. This paper reports for the first time, to our knowledge, a description of birds using cars to shelter from rain or snow. Moreover, some individuals were engaged in continuous round trips between the car and bushes, seemingly to detect potential predators that would not be visible to the individuals under the car. Further study should examine the diversity of foraging and non-foraging innovations in different groups of birds, in order to better understand the evolution of behavioral flexibility and cognition in non-human animals.

Kleptoparasitism by Grey Kingbirds (Tyrannus dominicensis) in Barbados

Abstract We observed Grey Kingbirds (Tyrannus dominicensis) from late February to May 2007 stealing food items from the bills of Carib Grackles (Quiscalus lugubris). This behavior occurred at two baited walk-in bird traps on the grounds of Bellairs Research Institute of McGill University in St James, Barbados. Grey Kingbirds were not seen entering traps, but were regularly observed in tree branches near traps, often chasing Carib Grackles and Zenaida Doves (Zenaida aurita) as they exited the traps with food. We describe six instances of kleptoparasitism by Grey Kingbirds from Carib Grackles. To our knowledge, this is the first report of kleptoparasitism for this species.