After finishing up GRE preparation on campus, I was anxious to get off the computer and get the rest of my day started. Summers in Davis mean temperatures climb, and the quick pace of the quarter system pales in comparison to the quicker pace of summer session courses. I, however, that summer of 2019 found myself embarking on a new “field” project, something I’d never done before. When people asked me what my job was, my favorite answer to reply was always, “I play with kittens.”

There is truth to that; for the past year I was involved in two cat behavior studies: the first was a feeding project where my mentor, Dr. Mikel Delgado was studying feeding behavior and food puzzle interactions in single and multi-cat households. The other study was looking at abnormal oral behaviors in orphaned neonatal kitten litters. I was examining the occurrence of non-nutritive sucking, sucking on objects or littermates without gaining nutrients, and how this might affect their sleep and activity levels. These two studies involved countless hours of video footage, watching frame after frame of adult cats living together, playfully swiping at food puzzles, or tiny shut-eyed kittens sucking on each other’s bellies. But this new project was different; this time around I would not be collecting data from behind a computer screen, I’d be actually handling kittens. My mentor, Dr. Mikel Delgado, and Kira Lowell, a veterinary student, wanted to examine how being separated from the mother would effect distress vocalizations and activity in kittens during a brief isolation. Since I have fostered kittens for many years and had experience analyzing video footage of cat behaviors, they brought me in to help out.

Cats are mammals, and as a quick reminder, that means from birth they are dependent on their mother’s for physiological needs (e.g. milk and warmth), as well as behavioral needs like comfort and protection. Under ideal conditions a neonatal kitten would be raised by a Queen (a female cat) alongside their littermates; this would comprise the “nest”. Many mammals (and even some species of birds) display behavioral signs of emotional distress through exhibition of vocalizations and heightened locomotor activity (i.e. movement) when separated from their nest [1]. If separated, often times neonates will orient their direction and their increase locomotor activity to attempt to return to their nest [2]. Mechanistically, vocalizations are thought to be closely related to an individual’s emotional state, due to extensive connections between the amygdala (an area of the brain thought to play an important role in emotion and behavior) and areas of the brain that process non-linguistic sounds [3]. Our study design was inspired by previous work where researchers conducted arena tests (observational tests done in sectioned, usually isolated, areas) to see if they could use this approach for studying animal personalities. They recorded vocalizations and displacement of limbs (to measure activity) on individual, mother-reared kittens for three-minute sessions and examined if the number of vocalizations and activity were consistent across time for each kitten [4]. Results showed that kittens who exhibited a high number of vocalizations in the first session were more likely to do so in later test sessions. They concluded that it was indeed a promising approach and we had ideas about how the paradigm could be used to look at responses to acute stressors.

To expand on this research, we decided to include a comparison group: orphaned kittens. Behavioral abnormalities have been observed in orphaned populations [5], such as the non-nutritive sucking I had been studying, but the effect of stressful events, such as brief isolation, has not been looked into. The study would determine if the responses of orphaned kittens during a 2-minute nest separation were different from kittens raised by their mothers. In addition to evaluating vocalizations and activity across time, our test sessions were set at specific time points (at one and three weeks old) so we could also evaluate age-related effects. The kittens used from our study came from different rescue groups including Orphan Kitten Project (an organization run by UCD veterinarian students), and Kitten Central, an organization in Placer country that aims to eliminate the need for euthanasia of neonatal kittens.

For data collection, Kira and I would meet up at a foster’s house, or an organization’s headquarters, unload all of our necessary equipment, and before getting down to business, we would meet the kittens to jot down their physical descriptions. Our mobile behavior lab set-up looked something like this: the arena was a fold up playpen (newly cleaned to avoid confounding scents of previously tested litters), covered with three pee pads, and surrounded by tripods and their respective cameras so we could capture every inch of the arena. We would place our test arena away from the “nest” area, in order to keep their mother’s or littermates’ calls out of their perception. Once I wrapped the stopwatch around my neck, it was time to hit record on the cameras. A single kitten was taken from the nest and placed in the center of the arena, signaling the start of the trial. We recorded them for two minutes, then reunited them with their litter. After repeating that process for each kitten until they were all tested, we could then spend some time fawning over how cute they were while weighing them and taking photos. Working in the “field” meant that we received many questions from foster parents. Some would be curious about the project, others asked us for general advice on kitten care, and some of the foster parents were even local undergraduate students who were curious about how I got into research.

Data collection challenges included driving around the greater Sacramento area to recruit enough kittens for the study, trying to identify differences in identical kittens, gathering information to approximate age, and remembering to change out the three pee pads in between every trial. Yet the greatest challenge of this project was three researchers sitting in a tiny, vet-school workspace, watching numerous videos of kittens, and trying to define behaviors in ways we could all agree on. As many behaviorists know, developing an ethogram (a catalog of behaviors an observed animal can exhibit) can be quite a difficult task, but then add to that tiny one-week old kitten squirming around a playpen, and the task becomes even more daunting. Would we consider movement to be any shift of a limb, or would it have to be a total body displacement? When is a sway considered a curl, and a curl considered a rotation? These are all important questions because in order to quantify behaviors and get accurate results, every researcher must be measuring every behavior the same way! After several ethogram iterations and multiple meetings of coding behaviors together, we arrived at an agreement that meant we could all reliably code the kittens’ behaviors.

As summer ended and the calls to test kittens were slowing down, it was time to look at the data we had gathered. To my surprise we’d performed 70 trials, and tested 49 kittens total (28 orphaned, 21 mother-reared, made up of 23 females, 26 male). We found that the orphaned kittens were more vocal and more active at both one and three weeks suggesting they might be more stressed and motivated to return to their littermates [6]. Further work could be done to see if this is a result of an adaptive stress responses due to being separated prematurely from their mother. All the results of this project are published in the journal of Applied Animal Behavior, so check it out!

My first experience in the “field” may not have been conventional; I wasn’t out trudging through the jungle or diving under the sea, but it reassured me that I wanted to continue doing research. Every day I got to come home, reminded of the fact that even though it was work, I was hanging out with kittens and doing cool research that could benefit them one day!

Sabrina Mederos recently graduated with her B.S. in Animal Science and Neurobiology. She previously worked with researchers at the UCD School of Vet Med studying the social behavior of neonatal kittens. She is a first-year graduate student in the ABGG working in Dr. Karen Bales’ lab. Her research will focus on the neurobiology of pair bonding in seahorses.

[All the photos were taken by Sabrina Mederos]

References

[1] Lingle, S., Wyman, M. T., Kotrba, R., Teichroeb, L. J., & Romanow, C. A. (2012). What makes a cry a cry? A review of infant distress vocalizations. Current Zoology, 58(5), 698-726. doi:10.1093/czoolo/58.5.698

[2] Freeman, N. C., & Rosenblatt, J. S. (1978). Specificity of litter odors in the control of home orientation among kittens. Developmental Psychobiology, 11(5), 459-468. doi:10.1002/dev.420110509

[3] Leitman, D.I., Edgar, J.C., Berman, J., Gamez, K., Frühholz, S., Robert, T.P. (2016). Amygdala and insula contributions to dorsal-ventral pathway integration in the prosodic neural network.  arXiv: Neurons and Cognition.

[4] Hudson, R., Rangassamy, M., Saldaña, A., Bánszegi, O., Rödel, H.G. (2015). Stable individual differences in separation calls during early development in cats and mice. Frontiers in Zoology, 12, S12. doi: 10.1186/1742-9994-12-s1-s1

[5] Hart, B. L. (1972). Maternal Behavior II – The nursing sucking relationship and the effects of maternal deprivation. Feline Practice, 2, 6-8.

[6] Lowell, K. J., Delgado, M. M., Mederos, S. L., & Bain, M. J. (2020). The effect of premature maternal separation on distress vocalizations and activity in kittens (Felis catus) during a brief nest separation. Applied Animal Behaviour Science, 105130.

[Edited by Karli Chudeau and Maggie Creamer]