As a parent to a newborn, I was drawn to the recent PLoS ONE paper ‘Creeping in the Night.’ I’m creeping in the night all the time — but I don’t get the excitement of working with mongoose, full moons, and unexpected den visits.
Drs. Carol Anne Nichols and Kathleen Alexander documented nocturnal behavior in a diurnal species when their camera traps captured some surprising late-night activity. Their paper, Creeping in the night: What might ecologists be missing? is part natural-history-note and part call-to-action for ecologists to shake off our perceptions of how animals partition their days and nights. As a reader, I came for the sleepwalking mongoose, but I stayed for the existential questions of how we structure our research activities and when binary traits might actually be blinders.
Nichols and Alexander have been studying banded mongoose behavior in Northern Botswana for years. The project began in 2000, Alexander joined as a field ecologist in 2014, and in 2016 they began camera trap research as a means to study behavior without observer presence. I asked if the den site selection for the camera traps, which spanned urban areas and natural habitats, was serendipitous or it they had intentionally radio-collared urban and country mongooses. They told me that they studied mongoose troops in “town” (ie urban areas of Kasane and Kazungula) and “park” (Chobe National Park) habitats to “understand how different landscapes influence wildlife behavior and potential impacts that could impose on pathogen transmission dynamics.” Within a month of deploying the camera traps, they caught a mongoose outside of a den at night on film.
“It was certainly an amusing discovery to find so early in the project,” says Nichols. “We were excited to see if more nocturnal detection were to come, or if, as we joked, that first mongoose was just sleepwalking.” After 215 trap days, they had photographs of mongooses at night from 7 trap days. Among these photographs, there was no pattern of more night-activity among town (vs. park) habitats or moonlit (vs. dark) nights. In at least two photos, a mongoose appears to be sneaking around a den of another troop. In a scene that could be the trailer for a mongoose-version of COPS, a series of photos captures one mongoose approaching a den at night, another mongoose emerging from the den, the ensuing chase, and hours later, a single mongoose returns.
Nichols and Alexander say they are now deploying more cameras in hopes of understanding ringed mongoose nighttime behvavior. “This discovery has changed the way we thinking about mongoose,” they write. “There is much more happening! This discovery has made us question all our assumptions. The mystery continues!”
In the same month that Nichols and Alexander published Creeping in the Night, Dr. Kaitlyn Gaynor and colleagues published the meta-analysis The influence of human disturbance on wildlife nocturnality in Science. Gaynor compiled 76 studies comprising 62 mammal species from across the globe to explore how daily patterns of wildlife activity responded to different types of human disturbance, including vehicles, resource harvesting, development, and recreation. Each study in the meta-analysis included data on animal nocturnality under conditions of low and high human disturbance. They found that across all the different types of human impacts, the mammals showed a significant increase in nocturnal activity compared to mammals in low-impact habitats.
This contrasts with the ringed mongoose — Nichols and Alexander’s data were not included in the meta-analysis, but they found no difference between the human-impacted town den sits and the park sites in mongoose night time activity. Nevertheless, at least in habitats marked by human disturbance, mongoose might not be the only so-called diurnal mammals creeping in night. This pattern of nocturnal behavior among mammals that we thought were diurnal calls into question the traditional dichotomy between day-time animals and night-time animals. In their Discussion, Nichols and Alexander write that this “limited approach [only looking at day time behavior] may fail to capture data critical to understanding the ecology, biology of a species, and the temporal nature of space use.” As she reviewed their photos, Alexander recalled Samuel Sneiders’ “The theory of ecology” — “specifically that heterogeneity was an underlying phenomenon of ecology. In our writing, we wanted to emphasize that these unexpected events are really the interesting nuggets of new discovery!”
The Discussion encourages ecologists to be open to temporal heterogeneity with references to classic ecological work in spatial heterogeneity. This connection made me think of a recent essay in Current Biology: Are the ghosts of nature’s past haunting ecology today? Here, Dr. Brian Silliman and coauthors explore trends of rebounding populations of large-bodied consumers. These species —for example, sea otters and alligators — seem to be expanding into habitats that ecologists thought were beyond their niche space. Often this is beause we decimated their populations before thoroughly studying their original ranges, and we’re working with incomplete baseline data. In both cases — spatially with rebounding sea otters and alligators and temporally with ringed mongoose — this limits our ability to provide recommendations for management and conservation. As Nichols and Alexander write, “This work emphasizes the idea that you don’t know what you don’t know.” They encourage researchers to:
Push the envelope and see what you find. It might make all the difference in your approach to management and effective conservation of a species. With mongoose, we realize that between group dynamics and contacts are more complicated than we thought with these nighttime excursions and we need to understand the drivers of this behavior to understand disease transmission in this population — a critically important management objective.
For me, during those rough 4 am feedings, it's weirdly comforting to think, maybe there's a mongoose out there who is also awake right now. But, as I look forward to returning to my own research next semester, I will be thinking about Nichols and Alexander's big question What might ecologists be missing? and working to better define the edge of my assumptions around my study system, species, and methods.
References:
Nichols, C. A., & Alexander, K. (2018). Creeping in the night: What might ecologists be missing? PloS One, 13(6), e0198277–7. http://doi.org/10.1371/journal.pone.0198277
Gaynor, K.M., Hojnowski, C.E., Carter, N.H. and Brashares, J.S. (2018). The influence of human disturbance on wildlife nocturnality. Science, 360(6394), pp.1232-1235.
Silliman, B. R., Hughes, B. B., Gaskins, L. C., He, Q., Tinker, M. T., Read, A., et al. (2018). Are the ghosts of nature’s past haunting ecology today? Current Biology, 28(9), R532–R537. http://doi.org/10.1016/j.cub.2018.04.002