Featured Research

from universities, journals, and other organizations

More Males Chimps Means More Territorial Patrols, Study Shows

Date:
October 18, 2005
Source:
University of Michigan
Summary:
A new study of wild chimpanzees shows that the biggest predictor of territorial boundary patrols is the number of males in the group. The more males in the group, the more often they will patrol their territory. Chimpanzees will sometimes attack and kill their neighbors during the rarely observed boundary patrols, said John Mitani, professor of anthropology at University of Michigan and co-author of the paper "Correlates of Territorial Boundary Patrol Behavior in Wild Chimpanzees," with David Watts of Yale University.

A new study of wild chimpanzees shows that the biggest predictor of territorial boundary patrols is the number of males in the group. The more males in the group, the more often they will patrol their territory.
Credit: Image courtesy of University of Michigan

ANN ARBOR, Mich. -- A new study of wild chimpanzees shows that thebiggest predictor of territorial boundary patrols is the number ofmales in the group. The more males in the group, the more often theywill patrol their territory.

Chimpanzees will sometimes attack and kill their neighbors duringthe rarely observed boundary patrols, said John Mitani, professor ofanthropology at University of Michigan and co-author of the paper"Correlates of Territorial Boundary Patrol Behavior in WildChimpanzees," with David Watts of Yale University.

Scientists have known for about 25 years that the patrols and fatalattacks occur, the question has been what accounts for the varyingnumber and frequency of these patrols and attacks.

Researchers hypothesized that five variables might impact the number ofpatrols: food availability, hunting activity, the presence of estrousfemales, intruder pressure, and male party size.

During boundary patrols, a group of males will rise without warning,form a single file line and silently depart the group, Mitani said. Thebehavior is markedly different from normal feeding parties, which areloud and scattered.

"What they are doing is actually seeking signs if not contact withmembers of other groups," Mitani said. "If the patrollers outnumberthem, then they will launch an attack." During the attacks, the chimpsbeat and often kill their neighbors.

The groups are generally all male, but on rare occasionsfemales---typically infertile---will join the patrol, Mitani said. Thepatrols and attacks are an important part of the chimp society, hesaid.

"They take up about two hours out of a 12-hour work day," Mitani said."That is not trivial exercise in terms of energy expended."

Chimpanzees live in fission-fusion societies. This means that likehumans living in a town, chimps form cliques and aren't all together inone place at the same time. But on patrol days, researchers found thata larger number of males gathered together than on non-patrol days. Theaddition of one male to the group increased the odds of a patrol by 17percent.

Mitani and Watts observed a community of about 150 chimps in Ngogo,Kibale National Park, Uganda and collected 24 month of data compiledover five years. The Ngogo community is significantly larger than twoother well-studied chimpanzee communities in Gombe andTaο, but the males in all three communities patrolled with equal frequencyon a per capita basis. However, the chimps in Ngogo patrolled abouttwice as often as the other communities, due solely to the large numberof males.

"The take home of all of this is that male numbers seem to matter, theyfind strength in numbers in doing this behavior, and they find strengthin making these attacks," Mitani said.

Chimps are our closest living relatives, and it's tempting to drawanalogies between human and chimp behavior, especially because it'svery rare for mammals to seek out and attack neighbors in this way. ButMitani said the situation is much more complicated than that.

"I think it is difficult to make any general conclusions about what this says about human behavior," he said.

###

For information on Mitani, visit: http://sitemaker.umich.edu/mitani

For information on anthropology at U-M, visit: http://www.lsa.umich.edu/anthro/


Story Source:

The above story is based on materials provided by University of Michigan. Note: Materials may be edited for content and length.


Cite This Page:

University of Michigan. "More Males Chimps Means More Territorial Patrols, Study Shows." ScienceDaily. ScienceDaily, 18 October 2005. <www.sciencedaily.com/releases/2005/10/051018072735.htm>.
University of Michigan. (2005, October 18). More Males Chimps Means More Territorial Patrols, Study Shows. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2005/10/051018072735.htm
University of Michigan. "More Males Chimps Means More Territorial Patrols, Study Shows." ScienceDaily. www.sciencedaily.com/releases/2005/10/051018072735.htm (accessed September 19, 2014).

Share This



More Plants & Animals News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) — Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) Video provided by AP
Powered by NewsLook.com
Chimp Violence Study Renews Debate On Why They Kill

Chimp Violence Study Renews Debate On Why They Kill

Newsy (Sep. 17, 2014) — The study weighs in on a debate over whether chimps are naturally violent or become that way due to human interference in the environment. Video provided by Newsy
Powered by NewsLook.com
Some Tobacco Farmers Thrive Amid Challenges

Some Tobacco Farmers Thrive Amid Challenges

AP (Sep. 16, 2014) — The South's tobacco country is surviving, and even thriving in some cases, as demand overseas keeps growers in the fields of one of America's oldest cash crops. (Sept. 16) Video provided by AP
Powered by NewsLook.com
Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

Scientists Given Rare Glimpse of 350-Kilo Colossal Squid

AFP (Sep. 16, 2014) — Scientists say a female colossal squid weighing an estimated 350 kilograms (770 lbs) and thought to be only the second intact specimen ever found was carrying eggs when discovered in the Antarctic. Duration: 00:47 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins