When the wild things are
Animal antics have captured
public attention and viral views across the U.S. in the last few years with the
advent of mini cameras that capture the movements of animals in front yards
nationwide, from bear to deer.
A URI-led team has gathered photographic data on daily
mammalian activity, studying 445 total species around the
world with surprising results. (URI Photos)
A University of Rhode Island-based group has taken the
camera concept one step further and then some, generating a massive dataset of
animal images, not for entertainment, but for science.
A host of camera sets in Rhode Island added to the data
gathered in a highly collaborative project producing a massive dataset of
animal images worldwide.
When the Global Animal Diel Activity Project results
were analyzed, researchers made some unique discoveries.
Put together, researchers across the country and around the
world generated a more focused picture of animal habits at various times of
day. The team created a camera trap dataset from 20,080 camera sites across 38
countries in six continents. They gathered and analyzed data on more than 400
mammal species, representing one of the largest camera trap datasets in
existence.
Together, they leveraged 8.9 million observations to create an enormous library of standardized activity estimates, finding that less than half of the estimates for the species studied were in agreement with their diel classifications in common reference literature.
Brian Gerber, a University of Rhode Island
research ecologist now with the U.S. Geological Survey at Colorado State
University, and Kadambari
Devarajan, URI research fellow and affiliate through 2024, led the
project team of over 200 collaborators that recently published their findings
in Science Advances. Gerber was the
project’s principal investigator along with Devarajan, an
engineer-turned-ecologist and National Geographic Explorer now based in Mumbai,
India.
URI postdoc Kadambari Devarajan sets a camera trap in
Zambia, one of the data sites for the project; the team gathered data from
20,080 total camera sites across 38 countries and six continents.
What’s the diel?
The idea for the study germinated 18 years ago when Gerber
was in Madagascar studying the fossa there for his master’s degree, and saw how
much variation there was when they were active. Fast forward to 2017 when
Gerber, now at URI, determined a methodology to explore the topic of animal
diel phenotypes with colleagues elsewhere in the field.
The project stands out for its scale, scope, and subject
matter. The study examined 445 terrestrial animals in total, from American
bison to zorillas, using data from cameras in a range of environments,
including arid desert, rainforests, arctic tundra, and savanna grasslands.
Gerber was surprised by the variability of when species were
active.
“I expected some variation,” he says, “but basically most species that we had adequate data on showed that they would change their diel activity.” For example, American black bears were found to be diurnal and cathemeral — nocturnal and irregularly active during the day and night — at different places and times.
The study examined how the general “global human footprint”
affects diel activity. Because the researchers were looking at data from both
urban and wild locales, they saw some species become more diurnal and others
more nocturnal. Overall, a third of species were affected by the human
footprint measure.
And how does this relate to the typical front-step or
back-deck wildlife observer, perhaps a human “lark,” spotting a raccoon
wandering by the front door or sighting a deer across the yard?
“The most striking thing is that when you are taught an animal is diurnal or is nocturnal, that is not always correct,” says Gerber. “Many terrestrial mammals will be diurnal sometimes and nocturnal or cathemeral other times. When you see a nocturnal species during the day, this is perhaps not as unusual as you might think.”
Species are often classified as diurnal, nocturnal, or
crepuscular (twilight) and sometimes cathemeral, as if these are immutable
phenotypic traits, adds Devarajan. When an animal is active is certainly
impacted by the species’ evolution, but it’s also a behavioral response to its
environment.
The data provided some surprising results, including that
much of the existing diel classifications are inaccurate. The team found
existing classifications were accurate for only 39% of all species studied.
Out of the species studied, 74% switched phenotypes. Species
that became more nocturnal with increasing global human footprint included
urban adapted mammals like the striped skunk, as well the snowshoe hare, gray
fox, and North American porcupine.
While light availability played a role in diel plasticity,
the team found that increasing anthropogenic pressure (environmental change
caused by people) impacted mammals, primarily in North America.
Animal behavior in focus
Animals’ diel activity is important for better understanding
changes in animal distribution and abundance, critical measures that are used
to determine species endangerment and legal harvest levels. The team’s results
will be useful for organizations and conservation initiatives since it’s
important to know when species are active in order to better conserve them,
especially in the wild.
As the world is experiencing a time of rapid environmental
change, says Gerber, many species are shifting their diel phenotypes with
unknown fitness consequences. Species that cannot shift or adjust behaviors may
experience negative outcomes if their behavior doesn’t change.
“Recognizing the fitness consequences of species’ diel
phenotype plasticity and lack thereof is an important next step to understand
the impacts of environmental change and can help direct conservation actions,”
Gerber says.
See the searchable library of the team’s results here and watch for a fun video
about the project created by the U.S. Geological Survey.
