Owls evolving due to climate warmth

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  1. Prinnctopher's Belt

    Prinnctopher's Belt Antiquities Friend SF Supporter

    Page last updated at 16:31 GMT, Tuesday, 22 February 2011

    Owls change colour as climate warms

    By Emma Brenand
    Earth News reporter


    Tawny owls turn brown to survive in warmer climates, according to scientists in Finland.

    Feather colour is hereditary, with grey plumage dominant over brown. But the study, published in the journal Nature Communications, found that the number of brown owls was increasing.

    As winters become milder, the scientists say, grey feathered tawny owls are likely to disappear.

    This study indicates that the birds are evolving in response to climate change.

    Dr Patrik Karell from the University of Helsinki, who led the study, gathered together data from long-term tawny owl studies carried out across Finland over the last 30 years.

    The owls can be split into two plumage-based categories - brown or grey.

    The colour of a tawny owl's plumage does not change throughout its lifetime, so Dr Karell and his colleagues were able to use the data to create "colour maps" of breeding pairs and their offspring.

    The maps showed that plumage colour was hereditary; pairs with grey plumage had the grey "version" of the gene that coded for plumage colour, so they produced grey offspring.

    In the case of mixed colour breeding pairs, the grey colour trait was "dominant", which meant that an owlet that inherited both grey genes and brown genes would be likely to have grey plumage.

    Lighter shade

    The team examined tawny owl data, which was compiled by amateur bird ringers from the Finnish Museum of Natural History.

    This revealed that, in years when winter weather was particularly severe, there was a higher mortality rate in the brown owl population.

    This could be because brown owls were more visible to predators when there was thick snow cover.

    Previous genetic studies have also suggested that brown owls' may have other disadvantages compared to their grey counterparts, including weaker immune systems and higher metabolic rates - meaning they need to forage more in order to survive.

    But as the winters have become warmer, and snow cover has been reduced, the brown tawny owl populations have greatly increased.

    Dr Karell told BBC News that the brown owls, which used to form 30% of the tawny owl population in Finland, now make up 50%.

    "Its survival has improved as winters have become warmer," he said. "In other words, climate-driven selection has led to an evolutionary change in the population."

    The results also suggest that a changing climate could, in some species, reduce the number and variety of characteristics that can be inherited.

    If the grey owls disappeared from the "gene pool", for example, there would be only one version of the colour gene to be found.


    http://news.bbc.co.uk/earth/hi/earth_news/newsid_9401000/9401733.stm
     
  2. IV2010

    IV2010 Well-Known Member

    :huh: I love owls!
    thanks for posting..interesting
     
  3. bhawk

    bhawk Well-Known Member

    are we talking about the tawny owl (strix aluco)?
    If so the colour variations that do occur will not "die out" in any way, the colour mutations can be quite a common occurence. For example i have seen pure black barn owls (tyto alba) and also barn owls from yorkshire having the colouring of the african subspecies.
    The weather will always knock out an estimated 70% of the young birds but this is rarely due to their colouration as tawny owls hunt in the dark and rely on stealth (silence) to catch their prey. Its also good to note that the tawny owl uses a method of hunting which is pretty lazy, they will perch on a fence post, low branch and wait for their prey to walk underneath them then they will simply drop onto the prey.
    i cannot see why visibility would make much impact on their hunting ability except for during breeding season where they will hunt at dawn and dusk (crepescular) and even during the day if they have a large clutch to feed.
    The birds camouflage is also not to do with their colouring but rather how the patterns on the feathers break up the outline of the bird making a tawny owl almost invisible (i have lost sight of a tawny owl while it was sat feet away from me and i knew roughly where it was, it was also sat with a red brick background yet still blended in perfectly)
     
  4. pit

    pit Well-Known Member

    I hope the Owls keep evolving, grow to 50 feet, and start eating the human race.

    :biggrin:
     
  5. IV2010

    IV2010 Well-Known Member

    :biggrin:
     
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