Written in Spring 2019

Abstract

The purpose of this review was to investigate the literature on cooperation in members of the family Corvidae, to examine where they excel and where they fall short. Cooperative behavior has been used in the past to investigate cognitive abilities, namely the ability to recognize kin, remembering who they’ve cooperated with in the past, reciprocity, tracking the reputation of others, understanding equity, and low temporal discounting. These abilities were discussed in the context of the literature mentioned in order to tie the research directly to the cognitive abilities of corvids. It was found that while members of this family excel at cooperating in different environments, they tend to have low inhibition control and do not attend to long-term consequences of defection. However, this lack of inhibition control may not suggest cognitive deficits, but simply the impulsive nature of animals in this family.           

  Keywords: Corvidae, cooperation, animal cognition, social behavior

Cooperation in the Family Corvidae

            Cooperation is a widely discussed and rigorously studied topic within the fields of animal behavior and behavioral ecology and was defined briefly by Stephens and Hauser (2004) as joint action for mutual benefit. However, authentic cooperation is difficult for scientists to pin down, as it is difficult to tell when animals truly understand the need to cooperate, as opposed to simply learning they need to complete a task with a conspecific. Because of this, reviews and studies have looked into the requirements for cooperation, particularly cognitive requirements, and have found a few common themes; for animals to cooperate, they need to possess the ability to remember who they’ve cooperated with in the past, engage in reciprocity, track the reputation of others, understand equity, and have low temporal discounting (Bear, Kagan, & Rand, 2017; Esteban, 2013; Stephens & Hauser, 2004). Because of these rigorous cognitive requirements, studying cooperation has often been used to understand the cognitive abilities of animal species, and cooperative behaviors have been shown in some of the most popular “smart” species such as elephants and dolphins (Kuczaj et. al, 2015; Plotkin et. al, 2011).

            There is another group of animals that have recently come into the spotlight on the cognitive stage; the Corvidae family. This group includes crows, jays, ravens, magpies, rooks, and more, and has been studied extensively in recent years to analyze their cognitive abilities, with shocking results. Most studies have found that members of this family are incredible problem solvers with a powerful memory and the ability to make and use tools (Clatyon et. al, 2007; Gould-Beierle, 2000; Hofmann et. al, 2016; St Clair et. al, 2016). However, cooperation across the entire family to assess cognitive abilities has yet to be examined. This review seeks to fill that gap in the literature and use cooperation to assess the cognitive abilities of members of the family Corvidae.

CORVIDAE SOCIAL STRUCTURE

            Corvids are known to exist in flocks and have very complex social structures. For instance, Braun et. al (2012) found that common ravens (Corvus corax) maintain strong social bonds both in captivity and in the wild, and that in the wild, subgroups of two to five individuals are shown to exhibit allo-preening and combined play behaviors. Another study investigated the social intelligence hypothesis in various bird species and found that corvids ranked high in their sociality, and even compared their social complexity to that of primates (Emery et. al, 2007). Because corvids live in these highly complex social environments with related and non-related individuals, it seems likely that cooperation would occur. Thus, the next topic of discussion is naturally when and how corvids cooperate, and when and how they fail to do so.

SUPPORT FOR COOPERATION

Cooperation in the lab

Cooperation tasks, such as the rope-pull task (Plotkin et. al, 2011), and game theory models of cooperation, such as the prisoner’s dilemma (Clements & Stephens, 1995), are commonly used to observe and assess cooperative behavior in a laboratory setting. Many studies have been done using these assays in corvids. For instance, Clements and Stephens (1995) found that when modeling a mutualism environment, wherein mutual cooperation pays best, blue jays (Cyanocitta cristata) readily cooperated with a partner for a food reward. The results of this study displayed that in a highly applicable model of cooperation, the jays were able to understand that in terms of immediate benefit, cooperation would offer the most rewards.

However, corvids are shown in other studies to go above and beyond simple reward assessments. A study done by Wascher and Bugnyar (2013) found that in two species of corvids (common ravens and carrion crows (Corvus corone)), individuals will not cooperate in situations when they are not receiving equal rewards, or when they recognize that their partner is receiving the same reward but not putting forth as much effort. While this study displays a lack of cooperation, it shows that ravens and crows can understand how much their partner is working, as well as the equity of the rewards they are receiving. This sensitivity to inequity is one of the cognitive requirements of cognition mentioned before, as well as the ability to track the reputation of others (which includes understanding how hard they work).

Lastly, Fraser and Bugnyar (2012) conducted a study looking at reciprocity and agonistic support (defined as a third party intervening in an ongoing conflict to attack one of the conflict participants, thus supporting the other) in common ravens. The researchers found that ravens will engage in long-term reciprocation of agonistic support and were more likely to support relatives and those who preened them. Interestingly, the ravens were not shown to engage in short-term reciprocation, which goes against the common trend in the literature that corvids attend to short-term rewards and reciprocity. The results of this study suggest that ravens check many of the cognitive requirement boxes, including the ability to remember who they’ve cooperated with in the past, the ability to engage in reciprocity, the ability to track the reputation of others, the ability to understand equity, and the ability to limit temporal discounting.

Cooperation in the wild

            While studies conducted in the lab are beneficial because of the high amounts of control a researcher can have over confounding variables, this unnatural environment can also lead to inaccurate understandings of an animal’s true abilities. Thus, it is incredibly beneficial for scientists to also look at behavior in the wild, especially when analyzing cooperation.

            One common cooperative behavior seen in a lot of corvid species is cooperative breeding, wherein individuals will band together to take care of the young of the group, whether they are directly related or not. Baglione et. al (2003) found this behavior in carrion crows, namely in that non-reproducing offspring and immigrant males aid breeding pairs in raising their young. Bosque and Molina (2002) found that cayenne jays (Cyanocorax cayanus) exhibit not only cooperative breeding, but also cooperative nest defending behaviors. Cooperative breeding is a simple yet incredibly common behavior, especially in New World corvids, which contain the most common corvid species such as jays, rooks, ravens, and crows. This behavior allows us to look at kin selection, one of the simplest bases of cooperation, which postulates that individuals care for those related to them in order to increase their direct and indirect fitness. While kin selection may be very basic, it does require various cognitive abilities, including the ability to recognize your kin.

            Outside of kin selection, wild corvid species have also displayed other cooperative behaviors. One study, conducted by Fraser and Bugnyar (2011), found that ravens will reconcile after fights with valuable partners, namely those who the individual will interact with in the future and who they share a valuable relationship with. Before this study, reconciliation had not been shown in avian species, but once again, corvids prove their abilities to understand their relationships with others outside of pair bonds, and how these relationships can help them in the future.

LIMITATIONS OF COOPERATION

            While corvids clearly display several cooperative behaviors that require vast cognitive abilities, some studies show that they often can fall short when it comes to working with others. There is one main shortcoming shown by the research: a lack of patience.

Lack of patience

            As mentioned before, except for a few studies like Fraser and Bugnyar’s (2012), which looked at reciprocity and agonistic support, most of the literature shows a lack of attention to long-term consequences and rewards in the corvid family. For instance, Clements and Stephens (1995) showed that while jays choose to cooperate in a mutualism environment, they do not choose to cooperate when placed in a prisoner’s dilemma environment, wherein the benefits of mutual cooperation are not much better than the benefits of mutual defection. This suggests that they attended more to the short-term rewards than the long-term consequences of defecting, and thus struggle with high temporal discounting. Other studies have shown this lack of cooperation in the absence of immediate benefit (Seed et. al, 2008; Stevens & Stephens, 2004).

Impulsive nature

            However, this lack of attentiveness to long-term consequences could be more related to impulsivity in the Corvidae family than to shortcomings in cognitive abilities. Previous research on corvids’ abilities to delay gratification shows that they struggle with this concept. For instance, Wascher et. al (2012) showed that crows are impulsive in their choice of rewards, even when they know a larger reward will come to them if they wait. So, for corvids to suddenly abandon their impulsive nature in order to cooperate would be abnormal, suggesting that this impulsivity is simply a barrier to cooperation that members of the family must overcome, regardless of their cognitive abilities.

CONCLUSION

            All in all, past research has shown that corvids possess many of the cognitive requirements for cooperation, including conspecific recognition, reciprocity, and an understanding of equity (Baglione et. al, 2003; Bosque & Molina, 2002; Clements & Stephens, 1995; Fraser & Bugnyar, 2012; Fraser & Bugnyar, 2011; Wascher & Bugnyar, 2013), and these findings exist both in lab settings and in the wild. However, they also showed a lack of inhibition control and high levels of temporal discounting in many corvid species (Clements & Stephens, 1995; Seed et. al, 2008; Stevens & Stephens, 2004). Despite these shortcomings, corvids show incredible levels of cooperation, suggesting high cognitive abilities, which falls in line with previous research done on their cognitive abilities outside of cooperation (Clatyon et. al, 2007; Gould-Beierle, 2000; Hofmann et. al, 2016; St Clair et. al, 2016). This review suggests many possible avenues of research, including looking into other examples of cooperation in corvids to expand the wealth of literature, or comparing the cognitive abilities of corvids and other non-human animals (or even humans themselves).

References

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