Nerding Out Over Masting, or Why Unusual Plant Reproduction Excites Animal Ecologists
As for many people, every pandemic month that passes marks another month since Iāve been able to travel. I realized recently that this is the longest time Iāve gone without getting on a plane since about the 5th grade (my parents divorced and lived in different states), and the longest Iāve gone without leaving the country since 2004. One reason I became an ecologist is because the work afforded me the opportunity to travel as part of my job, and that aspect is one of the main things I love about my work. For many tropical ecologists, the pandemic has marked a year of lost opportunities to travel to our field sites. Though my ongoing projects will survive this missed year of data, I miss the forest, and have spent many hours remembering all the things that made me fall in love with tropical field work in the first place.
Figure 1. Seedlings at Danum Valley, Sabah, Malaysia, October 2019.
One of my favorite forest phenomena is masting. Trees in the family Dipterocarpacae dominate SE Asian rainforests. These are the worldās tallest rainforest trees, reaching more than 90 meters in height, and they reproduce by masting, which are irregular fruiting events. In northern Borneo, there is no set wet or dry season; rain falls year-round but there are sporadic dry periods that vary from year to year. Thus, there is no regular spring/flowering season like we have here in the US. Instead, the Dipterocarps reproduce in masting events, usually following strong droughts. The reason animal ecologists get excited by these masting events is because during these periods the forest seems to explode with life. The first time I went to one of my field sites (Danum Valley) was during a masting event (2010), and I had no idea how rare and special it was. I thought that it was normal to see two clouded leopards eating a mouse deer, or to see orangutans pretty much every day, or to have elephants tip over your car while youāre out surveying frogs (true story!). In the following years, I realized how incredible it was to have been there at that time. I was a little sad that my chances of seeing another masting event were low, but I got lucky again in 2019 when I spent a month at Danum during its most recent masting year.
As a herpetologist, I admit that I donāt fully appreciate all of the botanical intricacies of masting. But the most visually noticeable thing about a masting event is that it makes the forest look as though someone has planted thousands and thousands of seedlings all over the forest floor. This is incredibly striking because much of the forest doesnāt normally have a lot of undergrowth, but rather widely spaced giant trees. It would be like seeing the redwood forest with seedlings blanketing the forest floor. I have a ridiculous number of pictures of both the forest floor and individual seeds and seedlings in an enormous variety of shape and size, and will gladly bore anyone willing to look at them.
Figure 2. Borneo short python (Python breitensteini), caecilian (Ichthyophis sp.), and palm civet (Paradoxurus philippensis).Ā
As I mentioned above, masting events also bring out heaps of animals that I donāt often otherwise see. In my first week, while setting up an introduction to electro-fishing for my students, we saw an orangutan about 30 meters away. He then came down to the forest floor, crossed the stream a little ways up from us, and walked off into the forest on the other side. Later that afternoon as I was setting up the exercise on a different stream, a lizard known as a water monitor (Varanus) was swimming downstream toward us, got spooked up onto shore by our presence, and ran right into the mouth of a concealed king cobra--!! While we couldnāt see the cobraās full body, we clearly saw its unmistakable head scales as it was pulling the Varanus back into its hiding spot, and heard the incredible growl that cobras let out when they donāt want to be bothered. The rest of the month saw numerous species of snakes, a giant softshell turtle, my 4th ever caecilian (a limbless amphibian), mom and baby civets (a small carnivorous mammal), and in keeping with the field sessionās mission, awesome frog data collected together with my students. While these animals are always present in the forest, masting events seem to bring them out in force, making all of them much easier to see.
As we start 2021, I am cautiously hoping that this year will see us all getting vaccinated, making travel safe once again. I hope to return to Borneo for more incredible encounters alongside my regular data collection, to better understand the incredible forest that hooked me into tropical field ecology in the first place.
Jennifer Sheridan is Assistant Curator in the Section of Amphibians and Reptiles at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.
