On the importance of accounting for alternative foraging tactics when assessing cognitive performance in wild animals.

Research Highlight: Reichert, S., Morand-Ferron, J., Kulahci, I. G., Firth, J. A., Davidson, G. L., Crofts, S. J., & Quinn, J. L. (2021) Cognition and covariance in the producer-scrounger game. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.13551. When foraging in groups, individuals can either acquire their own resources, as producers, or profit from the work of other individuals, as scroungers. Individuals vary in how much they rely on one foraging tactic over the other. Yet, each of these foraging tactics presents unique cognitive challenges. Using a field experiment with a mixed-species flock of birds, Reichert et al. (2021) investigated how production learning (i.e. successfully feeding from their assigned rewarded feeder) and scrounging propensity (i.e. collecting food from a non-assigned feeders by following another individual) are related at an individual level, as well as the repeatability of both production learning and scrounging propensity. The authors show that overall, (a) individuals learned to scrounge, (b) individuals who rely more on scrounging took longer to learn their assigned feeder and (c) variation in each cognitive trait was mostly explained by individual behavioural flexibility rather than by consistent differences between individuals. Since learning was negatively correlated with the use of an alternative foraging tactic (i.e. scrounging), results of this study also suggest that individual choice of foraging tactics should be considered when evaluating cognitive abilities in wild animals.

Conspecific presence, but not pilferage, influences pinyon jays' (Gymnorhinus cyanocephalus) caching behavior.

Caching species store food when plentiful to ensure availability when resources are scarce. These stores may be at risk of pilferage by others present at the time of caching. Cachers may reduce the risk of loss by using information from the social environment to engage in behaviors to secure the resource-cache protection strategies. Here, we examined whether pinyon jays, a highly social corvid, use information from the social environment to modify their caching behavior. Pinyon jays were provided with pine seeds to cache in two visually distinct trays. The cacher could be observed by a non-pilfering conspecific, a pilfering conspecific, or an inanimate heterospecific located in an adjoining cage compartment, or the cacher could be alone. After caching, the pilfered tray was placed in the adjoining compartment where caches were either pilfered (pilfering conspecific and inanimate heterospecific conditions) or remained intact (non-pilfering conspecific and alone conditions). The safe tray was placed in a visible, but inaccessible, location. Overall, pinyon jays reduced the number of pine seeds cached in the pilfered tray when observed, compared with caching alone. However, their caching behavior did not differ between the pilfering conspecific and the non-pilfering conspecific conditions. These results suggest that either pinyon jays were unable to discriminate between the pilfering and non-pilfering conspecifics, or they generalized their experience of risk from the pilfering conspecific to the non-pilfering conspecific. Thus, we report evidence that pinyon jays use cache protection strategies to secure their resources when observed, but respond similarly when observed by pilfering and non-pilfering conspecifics.

Motoric self-regulation by sled dogs and pet dogs and the acute effect of carbohydrate source in sled dogs.

Inhibitory control is a term used to envelop a collection of processes that allow an organism to refrain from engaging in an inappropriate prepotent or responsive behavior. Studies have examined the propensity of inhibitory control by nonhuman animals, from the cognitively complex processes involved in self-control to potentially less cognitively taxing processes such as motoric self-regulation. Focusing on canines, research has suggested that the domestication process as well as experiences during ontogeny contribute to inhibitory control. Diet may also play an important role in an individual's ability to self-regulate. This study examined this possibility by investigating motoric self-regulation in sled dogs, using three well-established tasks (i.e., A-not-B Bucket, Cylinder, and A-not-B Barrier tasks), performed after consumption of one of three dietary treatments with different glycemic index values. We also compared the performance of sled dogs during these tasks with results previously obtained from pet dogs. Overall, the results show many similarities in the performance of sled dogs and pet dogs on the motoric self-regulation tasks, with the notable exception that sled dogs may have a stronger spatial perseveration during the A-not-B Bucket task. Previous research findings reporting a lack of correlation among these tasks are also supported. Finally, during the early postprandial phase (period after consumption), dietary treatments with different glycemic index values did not influence self-regulatory performance for sled dogs.

Individual performance across motoric self-regulation tasks are not correlated for pet dogs.

Inhibitory control, the ability to restrain a prepotent but ineffective response in a given context, is thought to be indicative of a species' cognitive abilities. This ability ranges from "basic" motoric self-regulation to more complex abilities such as self-control. During the current study, we investigated the motoric self-regulatory abilities of 30 pet dogs using four well-established cognitive tasks - the A-not-B Bucket task, the Cylinder task, the Detour task, and the A-not-B Barrier task - administered in a consistent context. One main goal of the study was to determine whether the individual-level performance would correlate across tasks, supporting that these tasks measure similar components of motoric self-regulation. Dogs in our study were quite successful during tasks requiring them to detour around transparent barriers (i.e., the Cylinder and Detour tasks), but were less successful with tasks requiring the production of a new response (i.e., A-not-B Bucket and A-not-B Barrier tasks). However, individual dog performance did not correlate across tasks, suggesting these well-established tasks likely measure different inhibitory control abilities, or are strongly influenced by differential task demands. Our results also suggest other aspects such as perseveration or properties of the apparatus may need to be carefully examined in order to better understand canine motoric self-regulation or inhibitory control more generally.

Corvids Outperform Pigeons and Primates in Learning a Basic Concept.

Corvids (birds of the family Corvidae) display intelligent behavior previously ascribed only to primates, but such feats are not directly comparable across species. To make direct species comparisons, we used a same/different task in the laboratory to assess abstract-concept learning in black-billed magpies ( Pica hudsonia). Concept learning was tested with novel pictures after training. Concept learning improved with training-set size, and test accuracy eventually matched training accuracy-full concept learning-with a 128-picture set; this magpie performance was equivalent to that of Clark's nutcrackers (a species of corvid) and monkeys (rhesus, capuchin) and better than that of pigeons. Even with an initial 8-item picture set, both corvid species showed partial concept learning, outperforming both monkeys and pigeons. Similar corvid performance refutes the hypothesis that nutcrackers' prolific cache-location memory accounts for their superior concept learning, because magpies rely less on caching. That corvids with "primitive" neural architectures evolved to equal primates in full concept learning and even to outperform them on the initial 8-item picture test is a testament to the shared (convergent) survival importance of abstract-concept learning.

Reporting and interpreting non-significant results in animal cognition research.

How statistically non-significant results are reported and interpreted following null hypothesis significance testing is often criticized. This issue is important for animal cognition research because studies in the field are often underpowered to detect theoretically meaningful effect sizes, i.e., often produce non-significant p-values even when the null hypothesis is incorrect. Thus, we manually extracted and classified how researchers report and interpret non-significant p-values and examined the p-value distribution of these non-significant results across published articles in animal cognition and related fields. We found a large amount of heterogeneity in how researchers report statistically non-significant p-values in the result sections of articles, and how they interpret them in the titles and abstracts. Reporting of the non-significant results as "No Effect" was common in the titles (84%), abstracts (64%), and results sections (41%) of papers, whereas reporting of the results as "Non-Significant" was less common in the titles (0%) and abstracts (26%), but was present in the results (52%). Discussions of effect sizes were rare (<5% of articles). A p-value distribution analysis was consistent with research being performed with low power of statistical tests to detect effect sizes of interest. These findings suggest that researchers in animal cognition should pay close attention to the evidence used to support claims of absence of effects in the literature, and-in their own work-report statistically non-significant results clearly and formally correct, as well as use more formal methods of assessing evidence against theoretical predictions.

Abstract-concept learning in two species of new world corvids, pinyon jays (Gymnorhinus Cyanocephalus) and California scrub jays (Aphelocoma Californica).

concepts require individuals to identify relationships between novel stimuli. Previous studies have reported that the ability to learn abstract concepts is found in a wide range of species. In regard to a same/different concept, Clark's nutcrackers (Nucifraga columbiana) and black-billed magpies (Pica hudsonia), two corvid species, were shown to outperform other avian and primate species (Wright et al., 2017). Two additional corvid species, pinyon jays (Gymnorhinus cyanocephalus) and California scrub jays (Aphelocoma californica) chosen as they belong to a different clade than nutcrackers and magpies, were examined using the same set-size expansion procedure of the same/different task (the task used with nutcrackers and magpies) to evaluate whether this trait is common across the Corvidae lineage. During this task, concept learning is assessed with novel images after training. Results from the current study showed that when presented with novel stimuli after training with an 8-image set, discrimination accuracy did not differ significantly from chance for pinyon jays and California scrub jays, unlike the magpies and nutcrackers from previous studies that showed partial transfer at that stage. However, concept learning improved with each set-size expansion, and the jays reached full concept learning with a 128-image set. This performance is similar to the other corvids and monkeys tested, all of which outperform pigeons. Results from the current study show a qualitative similarity in full abstract-concept learning in all species tested with a quantitative difference in the set-size functions, highlighting the shared survival importance of mechanisms supporting abstract-concept learning for corvids and primates. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Individual exploratory responses are not repeatable across time or context for four species of food-storing corvid.

Exploration is among one of the most studied of animal personality traits (i.e., individual-level behavioural responses repeatable across time and contexts). However, not all species show clear evidence of this personality trait, and this is particularly so for members of the Corvidae family. We assessed the exploratory behaviour of four food-caching corvid species: pinyon jays (Gymnorhinus cyanocephalus), Clark's nutcrackers (Nucifraga columbiana), California scrub jays (Aphelocoma californica), and black-billed magpies (Pica hudsonia). Contextual repeatability was assessed through examining behavioural measures during the Novel Environment task and the Novel Object task, whereas temporal repeatability was assessed by examining changes in these measures over repeated trials. Our results suggest that, for corvids, an individual's exploratory behaviour was not repeatable across contexts or over time. Hence, we found no evidence that exploration constitutes a personality trait for these species of corvid. We did find differences in exploratory behaviour, at a species level, that may be explained by relative reliance on cached food.

Trialling Meta-Research in Comparative Cognition: Claims and Statistical Inference in Animal Physical Cognition.

Scientific disciplines face concerns about replicability and statistical inference, and these concerns are also relevant in animal cognition research. This paper presents a first attempt to assess how researchers make and publish claims about animal physical cognition, and the statistical inferences they use to support them. We surveyed 116 published experiments from 63 papers on physical cognition, covering 43 different species. The most common tasks in our sample were trap-tube tasks (14 papers), other tool use tasks (13 papers), means-end understanding and string-pulling tasks (11 papers), object choice and object permanence tasks (9 papers) and access tasks (5 papers). This sample is not representative of the full scope of physical cognition research; however, it does provide data on the types of statistical design and publication decisions researchers have adopted. Across the 116 experiments, the median sample size was 7. Depending on the definitions we used, we estimated that between 44% and 59% of our sample of papers made positive claims about animals' physical cognitive abilities, between 24% and 46% made inconclusive claims, and between 10% and 17% made negative claims. Several failures of animals to pass physical cognition tasks were reported. Although our measures had low inter-observer reliability, these findings show that negative results can and have been published in the field. However, publication bias is still present, and consistent with this, we observed a drop in the frequency of p-values above .05. This suggests that some non-significant results have not been published. More promisingly, we found that researchers are likely making many correct statistical inferences at the individual-level. The strength of evidence of statistical effects at the group-level was weaker, and its p-value distribution was consistent with some effect sizes being overestimated. Studies such as ours can form part of a wider investigation into statistical reliability in comparative cognition. However, future work should focus on developing the validity and reliability of the measurements they use, and we offer some starting points.

Linking songbird nest predation to seedling density: Sugar maple masting as a resource pulse in a forest food web.

The ecological literature presents considerable evidence for top-down forcing on the maintenance of species diversity. Yet, in temperate forests, bottom-up forces often exert a strong influence on ecosystem functioning. Here, we report on the indirect influence of a pulsed resource, sugar maple (Acer saccharum) seed production, on nest survival in a migratory songbird. We hypothesized that seed production in year t would determine daily nest survival rate in year t + 1 through its effects on seed-eating rodents. We used the density of sugar maple seedlings (with cotyledons) in year t + 1 as a proxy for seed production in year t and predicted that it would be inversely related to songbird nest survival the same year. We estimated the density of sugar maple seedlings, eastern chipmunk (Tamias striatus) activity, and daily nest survival rate in the ovenbird (Seiurus aurocapilla) over four successive years in a northern hardwood forest of New Brunswick, Canada. Seedling density varied by two orders of magnitude between years, whereas an index of chipmunk activity changed by an order of magnitude. Both variables were positively correlated and negatively correlated to daily nest survival rate. A logistic-exposure model including only seedling density received the greatest level of support (lowest AICc). Previous studies have reported the effect of sugar maple masting on seed-eating rodent populations, but the strong link we report between seedling density and songbird nest survival is novel. A nocturnal seed-eating nest predator, deer mouse (Peromyscus maniculatus), was not considered in our models, which may explain why chipmunk was not the best predictor of daily nest survival rate. The trophic linkages we observed are remarkably strong for a temperate forest ecosystem and might become more prevalent in northeastern North America, at least on calcium-rich soils, with the loss of large-diameter beech trees as a result of beech bark disease.

ENSO, nest predation risk, food abundance, and male status fail to explain annual variations in the apparent survival rate of a migratory songbird.

Adult mortality can be a major driver of population decline in species whose productivity is relatively low. Yet, little is known about the factors influencing adult survival rates in migratory bird species, nor do we know much about the longer-term effects of habitat disturbance on the fitness of individuals. The Ovenbird (Seiurus aurocapilla) is one of the vertebrate species most sensitive to forest management, yet it is still common and widespread. We monitored the fate of 330 colour-banded Ovenbird males in four pairs of 25-ha plots during 9 successive breeding seasons. One plot of each pair was treated through selection harvesting (30-40% basal area removed) during the first winter. We tested the following hypotheses: (1) higher physiological costs in harvested plots as a result of lower food abundance will reduce apparent survival rate (ASR) relative to controls; (2) lower ASR following years with low nest survival and higher probability of renesting; (3) fluctuations in ASR reflecting El Niño Southern Oscillation (ENSO); and (4) higher ASR in returning males than in recruits (unbanded immigrants) owing to greater site familiarity in the former. We tested the relative importance of these hypotheses, or combinations thereof, by generating 23 models explaining variation in ASR. The year-dependent model received the most support, showing a 41% decrease in ASR from 2007 to 2014. The important year-to-year variation we observed in ASR (Σw(i) = 0.99) was not explained by variation in nest predation risk nor by ENSO. There was also little evidence for an effect of selection harvesting on ASR of Ovenbird males, despite a slight reduction in lifespan relative to males from control plots (2.7 vs 2.9 years). An avenue worth exploring to explain this intriguing pattern would be to determine whether conditions at migratory stopover sites or in the wintering area of our focal population have gradually worsened over the past decade.