by Emily Grout
At the beginning of the year, I travelled to Barro Colorado Island, which is situated in the Panama Canal, to spend 3 months studying the fascinating social behaviour of female white nosed coatis (Nasua narica). Coatis are a fantastic species to study due to their intriguing social system in which only the females are social, living in groups of varying size and relatedness. They are, in fact, the opposite of what they are locally called in Spanish: ‘Gato Solo’ meaning ‘alone cat’ - which was likely named after the solitary males who only join the female groups during the breeding season. Coatis are in the Procyonid family along with racoons, kinkajous, olingos and others. They are omnivorous but have a sweet tooth for fruits. They are the only member of the family which are diurnal, but their eye-sight is not the sharpest as they spend most of their time using their distinctive long noses to sniff out food.
I was bursting with enthusiasm when I arrived on the island and was keen to get into the forest as soon as I could. I had been planning this field season for months and was excited to finally catch sight of my first ‘Nasenbär’ (the German name for coati which sweetly translates as ‘nose bear’). It wasn’t long on my first venture into the forest before I came across a large group of females eating the ripe Dipteryx fruits on the forest floor, however it wasn’t much longer before they dashed away from my sight. From this first brief encounter, I knew that the next few months would be thrilling yet challenging ones.
Two young coatis watching me closely from a tree. This commonly occurred when I was trying to follow them.
I have been fascinated by the mechanisms which allow social groups to function, especially in tropical forest habitats which are rich in biodiversity and are temporally and spatially variable in food resources and climatic conditions. Living in forests can be a challenging place to navigate and communicate visually due to its structure, so for many species, vocalisations are used. This is what prompts my question: What mechanisms are used to maintain cohesion in social groups? To answer this, I am using new technologies to collect data which does not require the presence of an observer. To record high-resolution GPS data with simultaneous audio recordings, custom-built collars have been made. These collars include a VHF radio transmitter and a drop off mechanism designed to fall off at a specific time so recapturing the animal is not necessary for collar retrieval. These collars sound like a behavioural ecologist’s dream, but as this is a fairly new and developing field of research, plenty of testing was needed before they could be worn by our furry friends. This testing included the unusual task of talking to the collars at precise times of the day, repeating the same walk multiple times with a horizontal 1 m long stick (with the collars attached to either end) as well as hiding the collars in secret places around the island where they would hopefully be undisturbed for a couple of hours a day. Sometimes in science we do the strangest things which seem completely reasonable to us yet look utterly bonkers.
After a week of GPS testing and acclimatising to the tropics, Dr Ben Hirsch arrived to teach me how to capture and collar the coatis. Ben has studied coatis for the past 20 years, and suggested that we focus trapping on some of the flat parts of the island that are easier for following coatis. I was warned that banana-management would become a major contributor to the success of coati capturing, I quickly learnt what shade of banana yellow was the finest for the coatis, as well as the optimal banana chunk width to attract them to the trap but keep them wanting more. I learnt over this first pilot season the challenges in which mammal capture presents and the best methods to minimise stress caused to the animal. With the help of my excellent field assistant Josué Ortega, we captured and collared 7 coatis from 2 groups (4 with VHF collars to find the groups and 3 GPS with audio recorders) in just over one week!
Josué Ortega and myself weighing a coati.
As many biologists know, the naming process for animals is of particular importance. The first group were called the Smarties and had individuals named after influential female scientists, some of the like include Rosalind Franklin, Marjory Stoneman Douglas, and Jane Goodall. To sprinkle some British-ness to the naming system, the second group were called the Downtons which contains characters from the infamous Downton Abbey series from the BBC.
Lady Mary is on the left who was caught by a camera trap and Lady Sybil on the right keeping a close eye on me.
Once we got the collars on the coatis, I spent the following weeks trying to follow the two groups. I wanted to collect audio recordings alongside behavioural observations which would be impossible to collect with the collar data alone. This meant I had to habituate at least one group to get detailed behavioural observations of their social interactions. From my previous wild mammal habituation experience, I knew that the secret to success would be a lot of delicate footsteps and humming regularly to let them know where I was. In reality this was a much harder job than anticipated as the coatis did not enjoy my company at all and a single snap of a branch would have 15 coatis running 50 m away in a heartbeat. Did I mention that forests tend to have branches on their floors?!
Radiotracking was used to follow the coatis. Photo taken by Christian Ziegler.
Sadly, this field season had to be cut 6 weeks short due to the coronavirus pandemic, and as a result I was unable to spend enough time to habituate a group. However, I managed to retrieve my collars before leaving, so I have now begun analysing their vocal communication as well as their movement patterns in anticipation of continuing the habituation process again soon to collect more observational data. I have learnt many things from this pilot field season. Working with wild mammals which are not in the slightest bit habituated can be very hard, and the questions I want to answer might seem simple in principle, but in reality will require time, luck, and banana-management. Also you should never plan a field season and expect to achieve every planned goal, a lot of planning can mitigate most issues, but the secret to being a successful field biologist is to expect the unexpected, be patient and own Mary Poppins’ bag full of four leaf clovers.