Field Notes: Bird Brains and Behavioral Flexibility

[Photo credit: Corina Logan]

Flexibility is the cornerstone of any PhD – whether it be recovering from failed experiments or tumultuous unproductive field seasons. One of the most useful skills to learn as a doctoral student is how to adapt and be flexible within your program or institution such that you can navigate all the inevitable obstacles along your path as you progress towards completing your degree. The COVID-19 pandemic has only enhanced this need for flexibility in graduate school, by introducing unexpected fluctuations in funding and variable access to necessary facilities or resources. Due to these circumstances, many international field studies have been stalled into the foreseeable future or canceled completely. Unfortunately, my dissertation plans fall into that category – an international field project completely derailed by a virus gone global. Thus, I was required to employ a little flexibility myself and reconsider how to conduct the remainder of my doctoral research stateside with a species that doesn’t live in my local backyard or parks. 

For years I have studied wild primates abroad in faraway countries including Madagascar, Costa Rica and the Democratic Republic of Congo. Before the pandemic began, I worked in Malaysia and Thailand studying the urban macaque populations for my doctoral research. By observing their behavior and conducting cognitive experiments, I have been able to look at how their social behavior, or willingness to interact with humans, influences their problem-solving abilities. I expect that more interactions with humans may expose these individuals to more novel foraging problems such as opening different types of closed food containers, which may positively improve their problem-solving abilities. Anyone who has purchased a bear-proof trash can or squirrel-proof bird feeder understands the woes of a human seeking to protect their food caches from being pillaged by unwanted urban animal visitors. By assessing the cognitive abilities of urban animals we can gain a better understanding of their cognitive limits in order to mitigate these types of human-wildlife conflict in areas where it is problematic. 

In addition to assessing how well these urban animals can solve problems, I am also interested in how animals can adjust their behavior to thrive in human-dominated environments. This concept of behavioral flexibility – or the ability to adjust your behavior to match current environmental or social conditions – is the main topic of my doctoral research. Not only do I think it is an imperative skill of graduate students, but likely of many other organisms in the natural world as well. 

[A photo of myself conducting behavioral observations on urban long-tailed macaques in Malaysia in 2019.] [Photo credit: Josephine Hubbard]

Despite my inability to travel internationally to conduct research on monkeys, I have been increasingly eager to work with live animals again and conduct behavioral research. Thus, while my field studies were still on hold due to the pandemic, I sought to gain some experience working with a new taxon of animals and to expand my research skills on my chosen topic of behavioral flexibility. To this end, I began working with a local researcher who studies the behavioral flexibility of birds living in the Sacramento valley.

[Female great-tailed grackle showing her flexibility skills on a fence-post in Sacramento, CA] [Photo credit: Corina Logan] 

Dr. Corina Logan is a researcher from the Max Planck Institute for Evolutionary Anthropology who studies how behavioral flexibility relates to environmental exploration and how that may contribute to a species’ ability to rapidly expand their geographic range. Her study species is the great-tailed grackle (Quiscalus mexicanus), which is a songbird that is originally from Central America. However, over the last 140 years, the range of this species has expanded rapidly across the US and into Canada. In order to understand if behavioral flexibility is a trait that allows these birds to adapt to new environments, Corina has sampled several populations of grackles across their current range, from the middle of their expansion front in Arizona to a population in Sacramento that is large enough for her study and near their northern expansion boundary. Her expectation is that populations closer to the original range in Central America will be less flexible since that is the environment the birds evolved to live in. However, the populations at the boundary of expansion are expected to be more flexible so they can explore new environments and facilitate their range expansion. 

[A “range map” of the great-tailed grackle showing an expansion in distribution from 1970 to 2018. The colored dots indicate Corina’s field sites to conduct flexibility experiments on the great-tailed grackle. Yellow represents the California site, orange represents the Arizona site and white represents the Panama site. Data has been collected in Arizona and California, but data collection has been postponed in Panama due to the COVID-19 pandemic. Photo taken from Figure 3 of [1]]

In order to test individuals within a population on their level of flexibility, Corina catches wild birds and brings them into a temporary aviary to conduct cognitive & flexibility tests. Once birds arrive at the aviary, we collect individual body measurements (aka morphometrics), body score metrics (such as fat storage), and biological samples such as blood and feathers for immunology and genetics. We also tag each bird with individually identifiable metal color bands that go on their ankles so we can identify them when they are in the wild. Once all these measurements are made, they are placed in their aviary where they will stay for the next few weeks while they are tested on several non-invasive cognitive procedures related to flexibility. 

[Photo of a grackle in their aviary – complete with perches and a plant for refuge and greenery. Just out of frame lies additional husbandry items including a water bowl, food bowl and bathing dish. Photo Credit: Josephine Hubbard] 

After a few days of getting used to the aviary, each bird is ready to start training on the cognitive tests! Although Corina performs an entire battery of tests with her birds, I was trained to conduct two particular tests while working with her last fall – a reversal learning test and a repeated innovation test. The reversal learning test is a traditional test of an individual’s level of flexibility while the repeated innovation test is a measure of how likely the individual is to solve multiple novel problems. 

The reversal learning test requires us to train the bird to retrieve hidden food from inside a small yellow PVC tube. Once the bird completes training, and we are confident that they understand how to retrieve hidden food, we begin the reversal learning process. During this test there are two colored tubes available, a light gray tube and a dark gray tube, one of which will always be baited with food. If and when the bird consistently retrieves food from the baited tube, we then reverse the rule in future trials. For example, if in the first set of trials food was found in the light gray tube, once reversed, food will only be found in the dark gray tube. This test is a classic test of flexibility since we can measure how long it takes for the bird to learn that the rule has been reversed. If the bird learns that reversal quickly (by choosing the dark gray tube consistently, in fewer trials) that bird is thought to be more flexible than a bird who learns that reversal slowly or not at all.

[Display of the two colored tubes (dark gray and light gray) used in the reversal learning test. Photo taken from Figure 2 of [1]]

The innovation test uses a multi-access puzzle box to assess how many of the five solutions the individual can consistently solve to open and gain access to a food reward. For these birds, a member of the grackle team, Kelsey McCune, constructed a multi-access box out of a small log, where four holes were carved out so as to provide a pocket for food in different locations along the log. Each of these was covered with a small plastic door (or in one case, a drawer) that needed to be removed in order to access the food reward.  Once the bird was observed to consistently solve a single solution (defined as receiving the food reward in three separate trials), that solution would remain locked open and without food for the remainder of the experiment. This required animals to explore new solutions and apply them to different doors and sometimes employ different motor patterns. Individuals who solved more solutions are considered better at innovating and solving novel problems. This test was particularly interesting to me since I will be conducting a similar experiment with captive monkeys later this year, so I was eager to gain this valuable hands-on experience and mentorship. 

[View of the multi-access puzzle log from above. Each solution is labeled with a letter A-D, while the motor patterns involved are described using white text. Photo taken from Figure 2 of [1]]

After a few weeks, most birds complete their battery of cognitive tests and are ready to be released back into the wild. To prepare them for this, we outfit each bird with a VHF transmitter so we can track them using a radio signal and follow them in the wild once they’ve been released. By using this tracking technology, Corina’s team is able to assess how individual performance in cognitive testing corresponds to natural habitat space-use and behavior. This is particularly exciting because it uniquely combines the experimental control of captivity with the natural ecology of the animal being studied, two aspects that are important to consider for all cognitive studies. Although most of my time working for this lab was spent in the aviaries performing cognitive testing, I was also able to spend “a day in the field” to learn how they observe wild birds and conduct field observations. Stay tuned for a future field notes piece outlining the details of our field-work with the grackles!

[Grackle Project team members Corina Logan (right), Kelsey McCune (middle) and Dieter Lukas (left) fit a male grackle with a radio transmitter before release back into the wild. These devices are affixed temporarily and fall off within a few months making it a safe and trusted practice for wildlife monitoring. Photo credit: Josephine Hubbard]

Corina and her team are currently wrapping up data collection here in Sacramento, and will soon be moving onto their next field site in Florida to test a new species, the boat-tailed grackle (Quiscalus major). Their goal in testing this species is to provide a comparison to the great-tailed grackle that is closely related yet does not show range expansion [1]. Corina’s team expects that, due to their lack of range expansion, boat-tailed grackle populations will be less flexible overall than great-tailed grackle populations. Although we only worked together for a few months, it is sad to watch the Grackle Project pack up their aviaries and move onto a new fieldsite. However, I am very grateful for my experience working with this phenomenal group of scientists. Their welcoming demeanor, engaging discussion and supportive mentorship has enhanced my skills in animal cognitive testing and exposed me to other important academic topics such as ethical publishing practices and how to foster an effective collaboration. I look forward to utilizing these flexibility skills that I’ve learned with this group to establish meaningful collaborations in the future as I continue to build my career in research.

Ultimately, the ability to adapt and employ behavioral flexibility in a world that is dynamic and changing is an incredibly useful skill. Despite my inability to travel due to a global pandemic, I was able to pivot my thinking and consider critically how the components of my research fit together and how these goals could be achieved in a completely novel domestic setting. Focusing more on my research questions and less on my study system helped me generalize my specific research on monkeys and apply those questions to other taxa. Overall, this has enhanced my scientific predictions and expanded my future research directions as a scientist. What I’ve learned throughout this experience is that with some creative thinking and hard work, you can foster your own research interests despite the inevitable challenges you will face in your career (pandemic or otherwise). So whether you are a monkey, bird or human – behavioral flexibility may be important to help turn those lemons into lemonade when things don’t go quite as you had planned (which, let’s be real, when does everything go as planned in science?). 

Josie Hubbard is a 5th year PhD student in the Animal Behavior Graduate Group at UC Davis. She studies how animals adapt to human-dominated environments, using monkeys in Asia as a model system. She conducts cognitive experiments with free-ranging and captive monkeys to better understand how individual characteristics influence performance and behavioral flexibility. 

References:

  1. Logan, C. J., McCune, K. B., Chen, N., & Lukas, D. (2020). Implementing a rapid geographic range expansion-the role of behavior and habitat changes (In principle acceptance by PCI Ecology of the version on 06 Oct 2020). http://corinalogan.com/Preregistrations/gxpopbehaviorhabitat.html

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