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A12 SCIENCE
Friday 13 November 2020
A crowded mountain can make silverback gorillas more violent

By CHRISTINA LARSON tat area. It turns out the
WASHINGTON (AP) — Go- answer depends partly on
rillas are highly sociable how they organize them-
animals – up to a point. A selves socially," said Tara
crowded mountain can Stoinski, a primatologist
make silverbacks more vio- and co-author of the new
lent, scientists say. paper. She is also president
Mountain gorillas spend of the Dian Fossey Gorilla
most of their time sleeping, Fund, a nonprofit research
chomping leaves and wild and conservation group.
celery stalks, and grooming During fieldwork in Rwanda,
each other's fur with long, Stoinski said she witnessed
dexterous fingers. These changes in gorilla behavior
large vegetarian apes are beginning in about 2007.
generally peaceful – unless Around that time, three
you're a rival gorilla. large family groups splin-
Researchers who analyzed tered into multiple smaller
50 years of demographic units, and the overall popu-
and behavioral data from lation also grew.
Rwanda found that as As a result, there were then
the number of gorilla fam- about 10 family groups in
ily groups living in a habi- the study area. The groups
tat increased, so did the spread out to occupy
number of violent clashes In this Sept. 2, 2019, file photo, a silverback mountain gorilla named Segasira walks in the Volca- more territory within Volca-
among them. Most often, noes National Park, Rwanda. noes National Park, but the
dominant males called sil- Associated Press number of violent clashes
verbacks led the fights. among them increased
Some gorillas, especially The frequency of gorilla considered to be "endan- in Africa and was not in- threefold. The number of in-
infants, perished, which family feuds was deter- gered" by scientists. volved in the paper. fant deaths increased five-
slowed population growth. mined not by the total "Normally when thinking "But it turns out we should," fold, and the population
"Encounters between number of individuals, but about conservation, sci- Bergl added, "especially for growth rate was halved.
groups can be violent. by the number of fam- entists focus on tangible, social animals like gorillas." The dissolution of the larger
Males will fight to protect ily groups in a region, the ecological issues like food Mountain gorillas live in for- family groups – one had
the females and infants study concluded. availability, degradation of ested parks on mist-cov- included 65 individuals –
in their group, and to ac- Mountain gorillas have habitat, hunting by humans ered volcanoes, spanning was probably related to
quire new females," said been a focus of intense — rarely do we think about parts of Rwanda, Uganda the deaths of charismatic
Damien Caillaud, a behav- research and conserva- how an animal's behavior and the Democratic Re- silverback leaders, said Sto-
ioral ecologist at the Uni- tion efforts in central Africa and social structure can public of Congo, where inski. "When these 'elder
versity of California, Davis, since the late 1960s. After influence population size," industries such as logging statesmen' gorillas got old-
and co-author of the new teetering near the edge of said Rich Bergl, a prima- and mining are banned. er and died, the younger
study published Wednes- extinction in the 1970s, the tologist at the North Caro- "Everyone wants to know males weren't able to keep
day in the journal Science population has rebounded lina Zoo, who also works how many gorillas can live the groups together," she
Advances. to just over 1,000 animals — on great ape conservation inside the protected habi- said.q

Female banded mongooses lead battle for chance to find mates

until the first animals run for- their territories and to take or minimizes inbreeding.
ward. females from other families. "We think females play a
"Then they bunch up into But individual mongooses role in inciting these con-
writhing balls, chaotic and almost never leave the flicts to escape the males
fast-moving, and you hear group they're born into. in their own family groups
high-pitched screeches," Banded mongooses are during the confusion and
said Michael Cant, a bi- known for almost unbreak- chaos of battle," said Cant.
ologist at the University of able devotion to their birth Their research, published
Exeter who has been study- family — as well as cooper- Monday in the journal Pro-
ing the species in Uganda ative living habits, including ceedings of the National
for 25 years. "We call it sharing den-guarding and Academy of Sciences,
mongoose warfare." pup-rearing responsibilities, found that almost all fights
The catlike striped mam- said Cant. are initiated by groups
mals only weigh up to 5 Combining field observa- when their females are in
pounds each, but the vi- tions and analysis of 19 estrus or fertile, which hap-
In this August 2013 photo provided by the Banded Mongoose
Research Project in November 2020, banded mongooses form cious fights can last more years of demographic and pens among all females
battle lines in Queen Elizabeth National Park, Uganda. than an hour. A question behavioral data for a pop- at the same time. Often
Associated Press that has intrigued Cant and ulation of 10 to 12 families the females take a lead in
other scientists is: Why do – about 200 mongooses steering groups to places
By CHRISTINA LARSON Each clan of about 20 ani- these social animals fight? at any time – Cant and where they will encoun-
AP Science Writer mals stands nose to nose, Chimpanzees are the most his colleagues have found ter combative neighbors.
WASHINGTON (AP) — When their ears flattened back, famous example of family- that at least one purpose of About 20% of pups in a
families of banded mon- as they stare down the en- oriented mammals who the fights is to allow females group are sired by males
gooses prepare to fight, emy. A patch of scrubby wage group warfare — a chance to mate with op- from opposing groups, DNA
they form battle lines. savannah separates them, both to defend or expand ponent males. That avoids analysis showed. q