Loading ...
Sorry, an error occurred while loading the content.

Re: [evol-psych] News: Cats could be more harmful to birds than previously suspected, scientists discover

Expand Messages
  • Edgar Owen
    There were naturally small cats (and canids) in most environments before humans wiped them out. Letting wild cats and wild dogs back into the environment
    Message 1 of 3 , Feb 28, 2013
    • 0 Attachment
      There were naturally small cats (and canids) in most environments before humans wiped them out. Letting wild cats and wild dogs back into the environment RESTORES it's natural balance...

      Edgar



      On Feb 27, 2013, at 10:02 PM, Robert Karl Stonjek wrote:

       


      Cats could be more harmful to birds than previously suspected, scientists discover

      February 27th, 2013 in Biology / Ecology
      Cats could be more harmful to birds than previously suspected, scientists have discoveredDomestic cat stalking.

      The study, by researchers at the universities of Sheffield and Exeter, suggests that killing birds is just a small part of the problem cats cause our feathered friends.

      Instead, the mere sight of a cat near their nests makes blackbirds feed their chicks less often. Not just that, but the shrieks the adult birds make trying to defend their nests end up attracting other predators like crows, magpies and rooks, exacerbating their plight.

      The only real way to stop their most damaging effects on the UK's ailing bird population is to keep them indoors permanently. But researchers concede this is likely to be problematic.

      Scientists have long suspected that such indirect effects may have a bigger effect on birds than cats killing them alone do.

      So, with the latest State of the UK's Birds survey suggesting that the nation's bird population has dropped from 210 million in 1966 to 166 million in 2012, Dr Colin Bonnington from the University of Sheffield and colleagues decided to test these so-called sub-lethal effects. These drive animals to change their behaviour, often in an effort to reduce their chances of being eaten.

      Bonnington put a stuffed cat, grey squirrel or rabbit near to blackbird nests for just 15 minutes, and recorded the parents' behaviour.

      He found that adult blackbirds were much more likely to call in alarm when they spotted the cat compared with the squirrel or the rabbit models. They were also more aggressive towards the cat model when they had older chicks in the nest.

      'This supports the parental investment theory, which predicts that parents should invest more in older rather than younger chicks,' says Dr Karl Evans from the University of Sheffield, the study's principal investigator.

      And when faced with the cat model, adult birds fed their chicks much less frequently for at least an hour and half after seeing the cat model. Previous studies suggest that cutting their food intake by this much, if sustained, could lead to a huge 40 per cent drop in the chicks' growth rates.

      This is the first time researchers have shown these indirect effects on bird populations and may help explain the drop in bird numbers over the last 40 years.

      Cats are one of the commonest predators of birds, certainly in towns and cities. Indeed cats are now so widespread that their numbers can exceed 1500 per square kilometre.

      'There is potential to lessen the impact of cats on birds by keeping cats inside more often. But this needs to be balanced against other interests,' says Evans.

      He acknowledges that this won't be easy.

      'In North America, more than half of cat owners keep their cats indoors, because they're afraid of their pets being run over by cars, or getting into fights with other cats. But in the UK, only three in a 100 cat owners do, which suggests there are likely to be strong cultural barriers against this,' says Evans.

      'It's imperative that assessments of the impact of predators on prey take these indirect effects into account, otherwise we're unlikely to design control strategies as effectively as possible,' he adds.

      Evans is keen to point out that while the study demonstrated that cats affect bird behaviour, it didn't reveal any influence on the size of bird populations.

      'Cats may just be changing the cause of mortality,' he says.

      The study was published in the Journal of Applied Ecology and was funded by the Natural Environment Research Council.

      More information: Bonnington, C. et al., Fearing the feline: domestic cats reduce avian fecundity through trait-mediated indirect effects that increase nest predation by other species, Journal of Applied Ecology 2013, 50, 15-24, doi: 10.1111/1365-2664.12025

      Provided by PlanetEarth Online

      This story is republished courtesy of Planet Earth online, a free, companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).

      "Cats could be more harmful to birds than previously suspected, scientists discover." February 27th, 2013. http://phys.org/news/2013-02-cats-birds-previously-scientists.html

      Posted by
      Robert Karl Stonjek



    • Bruce Lepper
      Cats kill 2.4 billion birds and 12 billion mammals every year in US alone Cat with American Coot by Debi Shearwater. Outdoor cats: Single greatest source of
      Message 2 of 3 , Feb 28, 2013
      • 0 Attachment

        Cats kill 2.4 billion birds and 12 billion mammals every year in US alone

        birds/2012_july/abc_cat_coot

        Cat with American Coot by Debi Shearwater.

        Outdoor cats: Single greatest source of human-caused mortality for birds and mammals, says new study
        January 2013. A new peer-reviewed study published and authored by scientists from two of the world's leading science and wildlife organizations - the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service (FWS) - has found that bird and mammal mortality caused by outdoor cats is much higher than has been widely reported, with annual bird mortality now estimated to be 1.4 to 3.7 billion and mammal mortality likely 6.9 - 20.7 billion individuals in the US alone.

        The study, which offers the most comprehensive analysis of information on the issue of outdoor cat predation, was published in the online research journal Nature Communications and is based on a review of 90 previous studies. The study was authored by Dr. Peter Marra and Scott Loss, research scientists at the Smithsonian Conservation Biology Institute and by Tom Will from the U.S. Fish and Wildlife Service's Division of Migratory Birds.

        Propblem is even worse than previously suspected
        According to Dr. George Fenwick, President of American Bird Conservancy, one of the leading bird conservation organizations in the U.S. and a group that has called for action on this issue for many years, "This study, which employed scientifically rigorous standards for data inclusion, demonstrates that the issue of cat predation on birds and mammals is an even bigger environmental and ecological threat than we thought. No estimates of any other anthropogenic [human-caused] mortality source approach the bird mortality this study calculated for cat predation."

        "To maintain the integrity of our ecosystems, we have to conserve the animals that play integral roles in those ecosystems. Every time we lose another bird species or suppress their population numbers, we're altering the very ecosystems that we depend on as humans. This issue clearly needs immediate conservation attention," he said further.

        Carnage
        "The very high credibility of this study should finally put to rest the misguided notions that outdoor cats represent some harmless, new component to the natural environment. The carnage that outdoor cats inflict is staggering and can no longer be ignored or dismissed. This is a wake-up call for cat owners and communities to get serious about this problem before even more ecological damage occurs," Fenwick said.

        The study's estimate of bird mortality far exceeds any previously estimated U.S. figure for cats. In fact, this magnitude of mortality may exceed all other direct sources of anthropogenic bird and mammal mortality combined. Other bird mortality sources would include collisions with windows, buildings, communication towers, vehicles, and pesticide poisoning.

        2.4 billion birds and 12 billion mammals killed by cats
        The study estimated that the median number of birds killed by cats annually is 2.4 billion and the median number of mammals killed is 12.3 billion. About 69 percent of the bird mortality from cat predation and 89 percent of the mammal mortality was from un-owned cats. Un-owned cats are defined to include farm/barn cats, strays that are fed but not granted access to human habitations, cats in subsidized colonies, and cats that are completely feral.

        Extinction cause
        Free-ranging cats on islands have caused or contributed to 33 (14 percent) of the modern bird, mammal, and reptile extinctions recorded by the International Union for Conservation of Nature Red List of threatened animals and plant species.

        Native species make up the majority of the birds preyed upon by cats. On average, only 33 percent of bird prey items identified to species were non-native species in 10 studies. Studies of mammals in suburban and rural areas found that 75-100 percent of mammalian prey were native mice, shrews, voles, squirrels, and rabbits, all of which serve as food sources for birds of prey such as hawks, owls, and eagles.

        The study charges that, "Despite these harmful effects, policies for management of free-ranging cat populations and regulation of pet ownership behaviours are dictated by animal welfare issues rather than ecological impacts.

        Projects to manage free-ranging cats, such as Trap-Neuter-Return (TNR) colonies, are potentially harmful to wildlife populations, but are implemented across the United States without widespread public knowledge, consideration of scientific evidence, or the environmental review processes typically required for actions with harmful environmental consequences."

        http://www.wildlifeextra.com/go/news/cat-birds-013.html#cr

        ------------------------------------------



        Edgar Owen a écrit :
        There were naturally small cats (and canids) in most environments before humans wiped them out. Letting wild cats and wild dogs back into the environment RESTORES it's natural balance...

        Edgar



        On Feb 27, 2013, at 10:02 PM, Robert Karl Stonjek wrote:

         


        Cats could be more harmful to birds than previously suspected, scientists discover

        February 27th, 2013 in Biology / Ecology
        Cats could be more harmful to birds than
previously suspected, scientists have
discoveredDomestic cat stalking.

        The study, by researchers at the universities of Sheffield and Exeter, suggests that killing birds is just a small part of the problem cats cause our feathered friends.

        Instead, the mere sight of a cat near their nests makes blackbirds feed their chicks less often. Not just that, but the shrieks the adult birds make trying to defend their nests end up attracting other predators like crows, magpies and rooks, exacerbating their plight.

        The only real way to stop their most damaging effects on the UK's ailing bird population is to keep them indoors permanently. But researchers concede this is likely to be problematic.

        Scientists have long suspected that such indirect effects may have a bigger effect on birds than cats killing them alone do.

        So, with the latest State of the UK's Birds survey suggesting that the nation's bird population has dropped from 210 million in 1966 to 166 million in 2012, Dr Colin Bonnington from the University of Sheffield and colleagues decided to test these so-called sub-lethal effects. These drive animals to change their behaviour, often in an effort to reduce their chances of being eaten.

        Bonnington put a stuffed cat, grey squirrel or rabbit near to blackbird nests for just 15 minutes, and recorded the parents' behaviour.

        He found that adult blackbirds were much more likely to call in alarm when they spotted the cat compared with the squirrel or the rabbit models. They were also more aggressive towards the cat model when they had older chicks in the nest.

        'This supports the parental investment theory, which predicts that parents should invest more in older rather than younger chicks,' says Dr Karl Evans from the University of Sheffield, the study's principal investigator.

        And when faced with the cat model, adult birds fed their chicks much less frequently for at least an hour and half after seeing the cat model. Previous studies suggest that cutting their food intake by this much, if sustained, could lead to a huge 40 per cent drop in the chicks' growth rates.

        This is the first time researchers have shown these indirect effects on bird populations and may help explain the drop in bird numbers over the last 40 years.

        Cats are one of the commonest predators of birds, certainly in towns and cities. Indeed cats are now so widespread that their numbers can exceed 1500 per square kilometre.

        'There is potential to lessen the impact of cats on birds by keeping cats inside more often. But this needs to be balanced against other interests,' says Evans.

        He acknowledges that this won't be easy.

        'In North America, more than half of cat owners keep their cats indoors, because they're afraid of their pets being run over by cars, or getting into fights with other cats. But in the UK, only three in a 100 cat owners do, which suggests there are likely to be strong cultural barriers against this,' says Evans.

        'It's imperative that assessments of the impact of predators on prey take these indirect effects into account, otherwise we're unlikely to design control strategies as effectively as possible,' he adds.

        Evans is keen to point out that while the study demonstrated that cats affect bird behaviour, it didn't reveal any influence on the size of bird populations.

        'Cats may just be changing the cause of mortality,' he says.

        The study was published in the Journal of Applied Ecology and was funded by the Natural Environment Research Council.

        More information: Bonnington, C. et al., Fearing the feline: domestic cats reduce avian fecundity through trait-mediated indirect effects that increase nest predation by other species, Journal of Applied Ecology 2013, 50, 15-24, doi: 10.1111/1365-2664.12025

        Provided by PlanetEarth Online

        This story is republished courtesy of Planet Earth online, a free, companion website to the award-winning magazine Planet Earth published and funded by the Natural Environment Research Council (NERC).

        "Cats could be more harmful to birds than previously suspected, scientists discover." February 27th, 2013. http://phys.org/news/2013-02-cats-birds-previously-scientists.html

        Posted by
        Robert Karl Stonjek



        Aucun virus trouvé dans ce message.
        Analyse effectuée par AVG - www.avg.fr
        Version: 2013.0.2899 / Base de données virale: 2639/6102 - Date: 13/02/2013
        La Base de données des virus a expiré.


      Your message has been successfully submitted and would be delivered to recipients shortly.