Navigation Links
Monkeys stressed from longer foraging times
Date:1/22/2013

Endangered Mexican howler monkeys are consuming more leaves and less fruit as a result of habitat disturbance by humans, which is forcing them to invest much more time foraging for sustenance and leading to increased 'stress' levels, as detected through hormone analysis.

The research, published today in the International Journal of Primatology, took place in the tropical rainforests of the Mexican state of Veracruz, which are being deforested and fragmented by human activity - primarily the clearing of forest for cattle raising. It shows that increases in howler monkey 'travel time' the amount of time needed to find requisite nourishment are leading to increases in levels of stress hormones called glucocorticoids.

These hormones are not only indicators of stress, but are also known to relate to diminished reproductive success and lower survival rates. Researchers believe the study could serve as a model for behavioural change and resulting health implications more generally in primates living in habitats disturbed by human activities, such as deforestation.

"Howlers are arboreal primates, that is to say they spend their wholes lives in the trees", said Dr Jacob Dunn from Cambridge's Department of Biological Anthropology, who carried out the research.

"As forests are fragmented, the howlers become cut off, isolated on forest 'islands' that increasingly lack the fruit which provide an important component of their natural diet. This has led to the monkeys expending ever more time and effort foraging for food, often increasing leaf consumption when their search is, quite literally, fruitless."

Fruit occurs in natural cycles, and the monkeys will naturally revert to 'fallback' foods, including leaves, when fruit is scarce. But as habitats shrink, and fruit is harder to find, leaves from second-choice plants, such as lianas, have increased in the Mexican howlers' diet.

While leaves may sound like a plentiful resource in a rainforest, many leaves are difficult to digest and can be filled with toxins - a natural defence mechanism in most trees and plants - so the monkeys are actually forced to spend more time seeking out the right foliage to eat, such as new shoots which are generally less toxic.

"The traditional view was that the leaves exploited by howler monkeys were an abundant food source - but this is not the case," said Dunn.

"The monkeys rely much more heavily on fruit than previously believed, and when turning to foliage for food - as they are increasingly forced to do they have to be highly selective in the leaves they consume, visiting lots of different trees. This leads to the increased 'travel time' and consequent high levels of stress we are seeing in these primates as their habitats disintegrate."

As trying to catch the howlers to examine them would in itself be highly stressful for the animal, the best way of evaluating stress levels in wild primates is by analysing their faeces for glucocorticoid stress hormones, which are general to all vertebrates.

Through statistical modelling, the researchers were able to determine that it is the 'travel time' - rather than the increased foliage intake - causing high levels of stress.

"Monkeys in disturbed habitats suffering high levels of stress is in itself unsurprising perhaps, but now we think we know why, the root cause from the primates perspective. Our results also highlight the importance of preserving and planting fruit trees - particularly those species such as figs that can produce fruit during periods of general fruit scarcity - for the conservation of howler monkeys said Dr Jurgi Cristbal-Azkarate, also from Cambridge, who led the research in collaboration with Dr Joaquim Vea from the University of Barcelona.

The authors say that further studies are required to fully understand the significance of increases in stress in howler monkeys living in disturbed habitats. "Determining the full relevance of our results for the conservation of primates living in forest fragments will require long-term studies of stress hormones and survival", said Dunn.


'/>"/>

Contact: Fred Lewsey
fred.lewsey@admin.cam.ac.uk
07-885-798-680
University of Cambridge
Source:Eurekalert  

Related biology news :

1. Do monkeys know what others need?
2. The old primates club: Even male monkeys ride their fathers coattails to success
3. Monkeys put off sex by bystanders
4. Estrogenic plants linked to altered hormones, possible behavior changes in monkeys
5. Monkey business: What howler monkeys can tell us about the role of interbreeding in human evolution
6. Networking ability a family trait in monkeys
7. For young birds, getting stressed out can be a good thing
8. Southampton to help develop new crops for water-stressed environments
9. Study suggests why some animals live longer
10. Global Surgical Devices Market Growth Driven by Improving Standards of Living and Longer Life Expectancies, Research Shows
11. Pain relief with PAP injections may last 100 times longer than a traditional acupuncture treatment
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Monkeys stressed from longer foraging times
(Date:2/5/2016)... DUBLIN , Feb. 5, 2016 /PRNewswire/ ... the addition of the "Global Facial ... offering. --> http://www.researchandmarkets.com/research/5kvw8m/global_facial ) has ... Facial Recognition Market 2016-2020" report to ... Markets ( http://www.researchandmarkets.com/research/5kvw8m/global_facial ) has announced the ...
(Date:2/3/2016)... , Feb. 3, 2016 Vigilant Solutions ... Police Department in Missouri solved ... plate reader (LPR) data from Vigilant Solutions. ... case in which the victim was walking out of a convenience store and ... space next to his vehicle, striking his vehicle and ...
(Date:2/2/2016)... , Feb. 2, 2016 Checkpoint ... that Rising Market Are you interested in ... forecasts revenues for checkpoint inhibitors. Visiongain,s report gives ... submarket, product and national level. Avoid falling ... what progress, opportunities and revenues those emerging cancer ...
Breaking Biology News(10 mins):
(Date:2/11/2016)... SAN DIEGO, Feb. 11, 2016  Neurocrine Biosciences, Inc. (NASDAQ: ... year ended December 31, 2015. --> ... reported a net loss of $29.3 million, or $0.34 loss per ... loss per share for the same period in 2014. For the ... of $88.9 million, or $1.05 loss per share, as compared to ...
(Date:2/11/2016)... Feb. 11, 2016  Wellcentive today announced it ... Portland, Oregon -based community care organization (CCO) ... health analytics, quality reporting and care management solutions ... its team of quality managers, analysts and care ... provider groups serving FamilyCare members. ...
(Date:2/11/2016)... ... February 11, 2016 , ... ... 150 years, continues today to pursue the highest level of accuracy and quality ... the AR9 Refractometer and the AR5 Refractometer. Accurate, reliable and tough enough ...
(Date:2/10/2016)... -- The Maryland House of Delegates and House Speaker ... Maryland School of Medicine Dean E. Albert Reece ... System President and CEO Robert Chrencik , MBA, ... given to the public by the leader of the ... and Mr. Chrencik for their contributions to our statewide ...
Breaking Biology Technology: