Animal behavior, like other kinds of phenotypic plasticity, is crucial for survival and reproduction in environments that vary over space and time. Behaviors themselves may need to be flexible when the distributions of environmental conditions themselves change; for example, short-term weather patterns and long-term climate conditions are changing due to human activity, and behavioral flexibility will likely be key to some population persisting during these changes and others going extinct. Thus, measuring this flexibility is key to understanding which species may be resilient to climate change.

Measuring behavioral flexibility is tricky as different studies may define and measure it differently and yet other studies may measure similar kinds of flexibility yet call them different things. This so-called "jingle-jangle" issue suggests that studies can more robustly measure a behavioral trait when they use multiple behavioral tests. An additional issue is that measuring behavioral traits that vary between individuals due to genetic or development effects, often referred to as "personality" traits, requires that those trait differences be repeatable across time and between individuals. 

With these issues in mind, McCune et al. (2019) presented a preregistration for experiments using a population of great-tailed grackles to investigate how behavioral flexibility relates to other important traits that are known to vary across individuals including exploratory behavior, boldness, and persistence and motor diversity in accessing a new food source. Behavioral flexibility is measured by the rate of learning a color associated with reward after first learning an association with a different color. That preregistration was recommended by PCI Ecology (Van Cleve, 2019). Now, McCune et al. (2025) present results from this study and find that only exploration of a novel environment and persistence were statistically repeatable behaviors. Both behaviors were not significantly correlated with behavioral flexibility. However, grackles that were trained to perform better in the color reversal learning task were more exploratory. This association between behavioral flexibility and exploratory tendencies may have evolved in grackles to help them survive in new environments, which they have proven very capable of doing as they have expanded their range in North American over the last 140 years (Wehtje, 2003).

There are a few key features of McCune et al. (2025) to merit recommendation. First, the authors are intent on demonstrating careful behavioral research practices including, as evidenced above, preregistering their hypotheses and predictions and making available both the preregistered and final analysis code. Second, the study demonstrates a thorough attempt to address two aspects that bedevil behavioral research, namely the "jingle-jangle" issue and repeatability of traits across individuals. Even after measuring multiple features of boldness, exploratory, persistence, McCune et al. (2025) find that only a subset of the measured behaviors are repeatable and only a subset of those are associated with behavioral flexibility. This suggests that only thorough studies like McCune et al. (2025) can start to probe difficult to measure behavioral associations that may be key to understanding how species will respond to our changing world.

References

McCune K, Lukas D,  MacPherson M, Logan CJ (2025) Behavioral flexibility is related to exploration, but not boldness, persistence or motor diversity. EcoEvoRxiv, ver.2 peer-reviewed and recommended by PCI Ecology https://doi.org/10.32942/X2H33F

Van Cleve, J. (2019) Probing behaviors correlated with behavioral flexibility. PCI Ecology, 100020. https://doi.org/10.24072/pci.ecology.100020

McCune K, Rowney C, Bergeron L, Logan CJ. (2019) Is behavioral flexibility linked with exploration, but not boldness, persistence, or motor diversity? (http://corinalogan.com/Preregistrations/g_exploration.html) In principle acceptance by PCI Ecology of the version on 27 Mar 2019

Wehtje, W. (2003) The range expansion of the great-tailed grackle (Quiscalus mexicanus Gmelin) in North America since 1880. Journal of Biogeography 30:1593–1607 https://doi.org/10.1046/j.1365-2699.2003.00970.x.

Behavioral plasticity, which is a subset of phenotypic plasticity, is an important component of foraging, defense against predators, mating, and many other behaviors. More specifically, behavioral flexibility, in this study, captures how quickly individuals adapt to new circumstances. In cases where individuals disperse to new environments, which often occurs in range expansions, behavioral flexibility is likely crucial to the chance that individuals can establish in these environments. Thus, it is important to understand how best to measure behavioral flexibility and how measures of such flexibility might vary across individuals and behavioral contexts and with other measures of learning and problem solving.
In this preregistration, Logan and colleagues propose to use a long-term study of the great-tailed grackle to measure how much they can manipulate behavioral flexibility in a reversal learning task, how much behavioral flexibility in one task predicts flexibility in another task and in problem solving a new task, and how robust these patterns are within individuals and across tasks. Logan and colleagues lay out their hypotheses and predictions for each experiment in a clear and concise manner. They also are very clear about the details of their study system, such as how they determined the number of trials they use in their learning reversal experiments, and how those details have influenced their experimental design. Further, given that the preregistration uses RMarkdown and is stored on GitHub (as are other studies in the larger project), their statistical code and its history of modification are easily available. This is a crucial component of making research more reproducible, which is a recent emphasis in behavioral sciences more broadly.
Reviewers of this preregistration found the study of substantial merit. The authors have responded to the reviewers' comments and their revisions have made the preregistration much clearer and cogent. I am happy to recommend this preregistration.

In this paper, Alan R. Rogers (2021) examines the dynamics of foraging strategies for a resource that gains value over time (e.g., ripening fruits), while there is a fixed cost of attempting to forage the resource, and once the resource is harvested nothing is left for other harvesters. For this model, not any pure foraging strategy is evolutionary stable. A mixed equilibrium exists, i.e., with a mixture of foraging strategies within the population, which is still evolutionarily unstable. Nonetheless, Alan R. Rogers shows that for a large number of competitors and/or high harvesting cost, the mixture of strategies remains close to the mixed equilibrium when simulating the dynamics. Surprisingly, in a large population individuals will less often attempt to forage the resource and will instead “go fishing”. The paper also exposes an experiment of the game with students, which resulted in a strategy distribution somehow close to the theoretical mixture of strategies.

The economist John F. Nash Jr. (1950) gained the Nobel Prize of economy in 1994 for his game theoretical contributions. He gave his name to the “Nash equilibrium”, which represents a set of individual strategies that is reached whenever all the players have nothing to gain by changing their strategy while the strategies of others are unchanged. Alan R. Rogers shows that the mixed equilibrium in the foraging game is such a Nash equilibrium. Yet it is evolutionarily unstable insofar as a distribution close to the equilibrium can invade.

The insights of the study are twofold. First, it sheds light on the significance of Nash equilibrium in an ecological context of foraging strategies. Second, it shows that an evolutionarily unstable state can rule the composition of the ecological system. Therefore, the contribution made by the paper should be most significant to better understand the dynamics of competitive communities and their eco-evolutionary trajectories. 

References

Nash JF (1950) Equilibrium points in n-person games. Proceedings of the National Academy of Sciences, 36, 48–49. https://doi.org/10.1073/pnas.36.1.48

Rogers AR (2021) Beating your Neighbor to the Berry Patch. bioRxiv, 2020.11.12.380311, ver. 8 peer-reviewed and recommended by Peer Community in Ecology. https://doi.org/10.1101/2020.11.12.380311