Phase One with the Lemurs

 Busy busy busy! I have now completed Phase One of my project with both the lemurs, and the red-tailed monkeys. It went fantastic! I lost track of the amount of blue and yellow boxes I assembled, painted, and stuffed, and am very thankful to the zookeepers I have been working with for putting the treats in the blue ones, and giving them to the animals every morning for four days this month. I made sure to bring each string a box of pastries as thanks! 😄Throughout Phase One, I also have presented my elevator pitch/research project summary to many zoo guests, staff, and volunteer/intern colleagues at the zoo who have asked me what it is I am doing while I am there.

I started Phase One with the lemurs (four ring -tailed lemurs, and two crowned lemurs) on June 15th, and start times varied between 9:40 – 10:15 am depending on when the zookeeper came out to put the boxes on exhibit. Mirroring the results with the red-tailed monkeys, the lemurs were all very excited about the boxes at first, and in the coming days, became less and less excited about them as their novelty wore off. However, they became more efficient at retrieving the treats from the blue boxes, and ignored the yellow ones more as time went on. Inside the blue boxes, the lemurs got bits of dried fruit like craisins, bits of carrot, and nuts --- all high value foods. The smaller crowned lemur couple do not mix with the ring-tailed lemurs, as I observed in my background observations from May, and they would frequently be chased away from the boxes when they came to investigate. However, they were persistent, and when the ring-tailed lemurs had moved on, the crowned lemurs couple would cautiously move in. They investigated pretty much only the blue boxes, and whether that was because they watched the ring-tailed lemurs interact with the boxes, or because the contents had been more opened and visible, or perhaps a combination of both, I don’t think I can know for sure. (However, according to the literature, lemurs exhibit social learning behaviors, and will learn how to do something/what to do by watching others do it first). I would not be surprised at all if the latter is what was going through their minds. https://link.springer.com/article/10.3758/LB.38.3.220

Photo of Oakland Zoo lemurs by Steven Gotz.

Day one, June 15th, and the lemurs were very interested in the new stimulus of the boxes introduced to them. As soon as the keeper placed the boxes down, two lemurs came over to examine them --- one looked at a blue box, and one a yellow. They curiously watched their keeper continue to put out the boxes, and then began to engage with them, figuring out how to open them and rifling through the contents. There were lots of revisits to the boxes, especially to one an individual lemur had previously been to. 

In order to make it fair for the lemurs against the more dexterous red-tailed monkeys, the lids were left not pushed in/secured all the way. Lemurs do not have as capable hands as the monkeys do, and I want to control for their physical differences to focus on their minds instead.

Day two, June 16th, and the lemurs were noticeably less excited about the boxes today, with overall less returns visits and less engagement, but increased expertise in opening the boxes. There was definitely more focus on the blue boxes today, but yellow boxes were still visited and opened. This follows the same pattern seen in Phase One with the red-tailed monkeys. Interestingly, the ring-tailed lemurs were more adamant about keeping the crowned lemurs away from the boxes today compared to yesterday. Perhaps they are now more aware that the boxes contain food, and therefore more concerned with protecting them?

Day three, June 17th, and the lemurs were less excited about the boxes, behaving more calmly when they were placed on exhibit than the previous days. Today was their quickest time opening them yet, and though they did continue to examine yellow boxes, more focus was given to the blue boxes, and no one bothered to pull the paper out of the yellow boxes today, as done in previous days. There was lots of decisions to not engage with a yellow box. For example, a lemur would come to sit nearby, glance over and see a yellow box and look at it for a bit, before turning their attention away and not bothering to go over to it. I also observed instances of lemurs walking between a yellow and blue box without engaging with either, although clearly seeing them, before turning around and coming over to the blue one to rifle through. Very noticeably more interest and revisits with blue boxes.

By Day four, June 18th, all of the blue boxes were opened and rifled through the fastest of all days, within four minutes of receiving them! They seemed to know the drill, and today only two yellow boxes were actually opened, but still no paper pulled out from them. However good and quick they were at opening the boxes, they were the least excited they had been to have them yet, and did not make as many revisits, preferring to rather move on to other activities. Because of this though, the crowned lemur male was able to come in and get some left over goodies from the blue boxes, ignoring nearby yellow boxes.

Overall general observations from Phase One: 

1) The monkeys do not share with each other as much as the lemurs do. Frequently there would be three lemurs to a box investigating and eating treats out of it together, but mostly the monkeys would take their box and run if another of their troop came to investigate. The female lemurs were more likely to share with one another than with their male troop member, however. (Which fits with their matriarchal social structure).

2) At first, it appeared that all of the boxes received an almost equal amount of attention, the monkeys especially spent a lot of time shredding, chewing on, and otherwise exploring all of the boxes the first day of Phase One. However, in the late days, yellow boxes were ignored more, and the boxes in general did not get as destroyed by the monkeys. The lemurs never destroyed any boxes, but would rather gently turn them over with their hands, stick their nose under the lid and explore the contents. They definitely used their face as an appendage rather than relying solely on their hands. The monkeys would use a lot of physical force and sometimes tear the lid of a box off completely.

 3) All animals opened the boxes more quickly towards the end of Phase One.

 4) Also towards the end of Phase One, yellow boxes were often not investigated at all, or saved for after the blue boxes had taken priority. 

5) Animals spent less and less time engaged with the boxes over the course of Phase One. As in, they would open them quicker, but have less revisits afterwards.

Now, the animals are all getting an eighteen-day absence from the boxes. It was originally only supposed to be a 7-9 day absence dependent on keeper schedules, but one of the red-tailed monkeys in my study has to have a routine medical procedure this week, and so it had to be pushed back as she will be gone for a day, and then the keepers have told me the group dynamic will be in flux for a few days afterwards and they may not be able to reliably get the monkeys into holding every day in order to put out the boxes. So I will now be prepping more boxes for Phase Two, to be undertaken with the monkeys starting June 29th.

I have lots of data, which is great! Making sense of it and organizing it will definitely be a new challenge for me. I will definitely be doing some investigating into how best to present it, and I will probably do a lot of drawing graphs by hand just to make sense of it all for myself first.