Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Surprising demographic shifts in endangered monkey population challenge conservation expectations

19.09.2012
At first glance, the northern muriqui monkey is a prime conservation success story.

These Brazilian primates are critically endangered, but in the past 30 years a population on a private reserve has grown from just 60 individuals to some 300, now comprising almost a third of the total remaining animals.

As the population grows, though, it is offering researchers a glimpse into a new phase of recovery as it begins to face the limitations of its habitat. A recent analysis of the factors contributing to this population's tremendous growth reveals surprising trends that raise new questions about conservation, recovery and what constitutes a healthy population.

University of Wisconsin–Madison anthropologist Karen Strier has led observational field studies of this muriqui population for 30 years, meticulously charting demographics and life history of hundreds of individual monkeys. An analysis, published Sept. 17 in the journal PLOS ONE with UW–Madison mathematical ecologist Anthony Ives, provides the most comprehensive, quantitative look to date at long-term demographic trends and the role of individual features such as fertility, mortality, and sex ratios.

The researchers used statistical models designed to handle multiple levels of data so they could construct a comprehensive view of the population while still accounting for variation among individual animals. The approach allowed them to identify specific demographic trends and their effects on the overall population size.

"By separating out these components we were able to see the patterns in the data," Strier says, many of which were unexpected. For example, the analyses revealed increases in both fertility and mortality – a surprising combination, especially in a population that is still growing. In addition, they documented a remarkable and unexplained shift in infant birth sex ratios from about one-third male to two-thirds male in just 28 years.

"It is an analysis that leads to more questions than answers," Ives says. A birth rate that continues to grow as the population expands flies in the face of most ecological thinking, he says, since demand for resources by larger populations usually reduces fertility. But without the observed fertility increases, the muriqui population would likely have plateaued around 200 individuals; instead, it has reached 300 and is still growing.

Strier believes the trends may be driven by behavioral changes. Though muriquis are typically arboreal animals, her field team has observed increased use of the ground – first for drinking and eating, then gradually for traveling, playing, and even mating. These data are still qualitative, but she suspects this behavioral innovation could help explain the rises in both fertility and mortality. The ground expands the monkeys' pool of available habitat and food resources but exposes them to additional dangers as well.

"On the ground, there are risks. We suspect there may be more pathogenic risks, and we know there are more predators," she says. Supporting a connection, mortality increased primarily in prime-aged males, who spend more time on the ground than females. "I've always thought it was increasing population size that was driving this increasing use of the ground, but never thought about what the potential consequences of the use of the ground might be for the population's rate of growth," she adds.

The apparent interactions between demography and behavior emphasize the need for ongoing population monitoring, Strier says. Her long-term study, in collaboration with Brazilian colleagues including biologist Sergio Mendes of the Universidade Federal do Espirito Santo, is showing that assumptions about population dynamics based on past observations may not hold true in the future.

Ives views the results as a cautionary tale for other threatened and endangered species, the vast majority of which are not monitored anywhere near as closely as Strier's muriquis.

"From the conservation standpoint I think a main message is, don't presume that the demographics will respond in a 'normal' way," he says. "Even if an area is protected you need to have a close gauge on what's going on. Protecting an area is not necessarily protecting a species."

Strier agrees that the analysis raises important questions about environmental carrying capacity – basically, how large of a population a habitat can support. "How long will it be able to grow, and if it does continue to grow, is it in danger of crashing?" she asks.

These are critical questions when considering management decisions, she adds, especially given that her study population represents a third of the entire muriqui species. On paper, population growth alone can look like success, but their demographic analysis reveals early indications of stress even as the population continues to expand.

At the same time, Strier says, their studies suggest a solution. "We know exactly what we need to do to alleviate it – expand the area, and there is area to expand the forest into. In a world with so many unsolvable problems, this seems like a solvable one."

Jill Sakai, (608) 262-9772, jasakai@wisc.edu

Note: Images to accompany this story are available at http://www.news.wisc.edu/newsphotos/strier-monkeys.html

Contact: Karen Strier, (608) 262-0302, kbstrier@wisc.edu; Anthony Ives, (608) 262-1519, arives@wisc.edu

Karen Strier | EurekAlert!
Further information:
http://www.wisc.edu

More articles from Ecology, The Environment and Conservation:

nachricht Machine learning helps predict worldwide plant-conservation priorities
04.12.2018 | Ohio State University

nachricht From the Arctic to the tropics: researchers present a unique database on Earth’s vegetation
20.11.2018 | Martin-Luther-Universität Halle-Wittenberg

All articles from Ecology, The Environment and Conservation >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: An energy-efficient way to stay warm: Sew high-tech heating patches to your clothes

Personal patches could reduce energy waste in buildings, Rutgers-led study says

What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...

Im Focus: Lethal combination: Drug cocktail turns off the juice to cancer cells

A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.

The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...

Im Focus: New Foldable Drone Flies through Narrow Holes in Rescue Missions

A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.

Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...

Im Focus: Topological material switched off and on for the first time

Key advance for future topological transistors

Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...

Im Focus: Researchers develop method to transfer entire 2D circuits to any smooth surface

What if a sensor sensing a thing could be part of the thing itself? Rice University engineers believe they have a two-dimensional solution to do just that.

Rice engineers led by materials scientists Pulickel Ajayan and Jun Lou have developed a method to make atom-flat sensors that seamlessly integrate with devices...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

ICTM Conference 2019: Digitization emerges as an engineering trend for turbomachinery construction

12.12.2018 | Event News

New Plastics Economy Investor Forum - Meeting Point for Innovations

10.12.2018 | Event News

EGU 2019 meeting: Media registration now open

06.12.2018 | Event News

 
Latest News

UNLV study unlocks clues to how planets form

13.12.2018 | Physics and Astronomy

Live from the ocean research vessel Atlantis

13.12.2018 | Earth Sciences

Stanford researcher deciphers flows that help bacteria feed and organize biofilms

13.12.2018 | Life Sciences

VideoLinks
Science & Research
Overview of more VideoLinks >>>