Reproductive speed protects large animals from being hunted to extinction

The slower their reproductive cycle, the higher the risk of extinction for large grazing animals such as deer and antelope that are hunted by humans.

The oft-cited causes of habitat loss and living in a limited geographic area also are significant risks for extinction of a species, but under hunting pressure it's reproductive speed that really matters, according to a new statistical analysis by evolutionary biologist Samantha Price, a postdoctoral fellow at the National Evolutionary Synthesis Center in Durham.

This key variable helps explain, for example, why the American bison was nearly wiped out in just a few years of intense hunting pressure with relatively slight habitat change while the white-tailed deer continues to grow in number despite hunting and suburban sprawl. The bison nurses its young for 283 days on average; the deer just 80, Price notes.

Price reported her findings online Wednesday, May 16, in the journal Proceedings of the Royal Society B. The work, supported by the National Science Foundation, is an offshoot of her Ph.D. dissertation at the University of Virginia.

Price did a complex statistical analysis of 144 species of hoofed mammals, including pigs, llamas, cattle, sheep, goats and antelopes, combining a global list of threatened species with data on hunting, land use and the animals' reproductive rates.

Where hunting isn't a factor, habitat loss is the biggest issue. But whether the threat comes from hunting or habitat destruction, extinctions such as this are "all human-caused at some level," Price said.

The worst-case scenario, she said, is where humans are expanding into an area and changing its habitat, and hunting the indigenous animals as they go. Three areas of the world -- West Africa, Indonesia and Malaysia, and South America -- are "hot spots" for hunting, and many species in these areas are threatened.

"The poorer the country, the greater the threat," Price said. Regional military conflicts also turn up the heat on species, as people in strife-torn areas will turn increasingly to "bush meat," including hoofed animals, to supplement their diets.

"Because these are large, plant-eating animals, they have a significant effect on the local ecology," Price said. These animals help disperse plant seeds through their manure and keep plant growth in check. "You can completely change the ecosystem without knowing it if you hunt these animals to extinction," she said.

Price isn't optimistic that much could be done to incorporate her findings into new game policies, but this new understanding of the importance of reproductive rates could help conservation managers zero in on which species are in the greatest peril.

Source: Duke University

Related stories:

Nature group says humpback whales recovering
(AP) -- The humpback whale, nearly hunted into history four decades ago, is now on the "road to recovery" and is no longer considered at high risk of extinction, an environmental group said Tuesday.
New evidence implicates humans in prehistoric animal extinctions
Research led by UK and Australian scientists sheds new light on the role that our ancestors played in the extinction of Australia's prehistoric animals. The study, published this week in the journal Proceedings of the National Academy of Sciences of the USA, provides the first evidence that Tasmania's giant kangaroos and marsupial 'rhinos' and 'leopards' were still roaming the island when humans first arrived. The findings suggest that the mass extinction of Tasmania's large prehistoric animals was the result of human hunting, and not climate change as previously believed.
Midge-hunting scientists tackle spread of devastating bluetongue virus
Scientists at the BBSRC-funded Institute for Animal Health (IAH) are stepping up the battle against the devastating and economically damaging bluetongue virus. By combining ingenious ways to trap and monitor midges with cutting edge computer modelling and weather predictions the IAH team are gaining an understanding of how the insects spread the disease so that they can improve surveillance methods and advise farmers how and when to protect their animals.
Scientists cheer gorilla find, but warn of threats
(AP) -- Can there be more lurking in the mist? Despite a startling find announced Tuesday that doubled the estimated number of western lowland gorillas in central Africa, scientists warned that hundreds of primate species remain in danger of extinction.
Extinction threat growing for mankind's closest relatives
Mankind's closest relatives – the world's monkeys, apes and other primates – are disappearing from the face of the Earth, with some literally being eaten into extinction.
Rock art marks transformations in traditional Peruvian societies
Peru is one of the Latin American countries, like Argentina and Brazil, where rock art is thought to have developed throughout a period stretching from 10,000 BC to 1500 AD. The wealth and diversity of the series of pictorial representations made during this period are now beginning to be appreciated by archaeologists. Recent investigations by an IRD researcher has given insights into the daily lives of human communities who lived in the coastal and mountainous areas of Peru during that era.
Simian foamy virus found in several people living and working with monkeys in Asia
A research team led by University of Washington scientists has found that several people in South and Southeast Asian countries working and living around monkeys have been infected with simian foamy virus (SFV), a primate virus that, to date, has not been shown to cause human disease. The findings provide more evidence that Asia, where interaction between people and monkeys is common and widespread, could be an important setting for future primate-to-human viral transmission. The study appears in the August issue of the journal Emerging Infectious Disease.
Bovine tuberculosis in wildlife threatens endangered lynx and cattle health
In an epidemiological survey of Spain's Doñana National Park, the findings of which are published on July 23 in the journal PLoS ONE, Christian Gortázar and colleagues studied the prevalence of bovine tuberculosis (bovine TB) infection among populations of wild boar, red deer and fallow deer in the national park, which is located in southern Spain. The researchers suggest that the results can be used to investigate bovine TB transmission dynamics between and within each species and to extrapolate the implications for spill-over to domestic cattle and wildlife management policies.

News discussion:

General Science news