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Bald Eagles and predation on loons

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  • Steve Gniadek
    Patrick s message about Bald Eagles and seabird predation, and then Dan s comments about Bald Eagles and predation of Common Loon chicks in Montana deserve
    Message 1 of 3 , Aug 4 8:06 PM
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      Patrick's message about Bald Eagles and seabird predation, and then Dan's comments about Bald Eagles and predation of Common Loon chicks in Montana deserve clarification. I'm not familiar with the situation Patrick presented, though it appears habitat changes were implicated in the increased predation. My concern is that some may erroneously derive from their comments a simplistic cause and effect relationship- a burgeoning Bald Eagle population has resulted in increased eagle predation on loon chicks, in the case of Montana. While that may well be true, there is more to the story.

      Eagles and loons evolved together, and are only beginning to adjust to burgeoning human populations and our impacts. By stopping the spread of DDT in the environment and through other protective measures humans have helped recover Bald Eagle numbers to approximately historic levels. But human development has eliminated nesting loons from some Montana lakes and continues to encroach on remaining loon territories. Impacts from lakeshore homes and associated activities, fishing, boating and other recreational activities, plus pollution and other environmental contaminants continue to reduce the effectiveness of loon nesting territories. Some nesting lakes are seeing increased competition for remaining territories, not because there are too many loons but because there is less available habitat.

      So the problem is not that Bald Eagles occasionally prey on loon chicks, that has been going on for millenia, but that human activities make loons less secure and more vulnerable to eagle predation and other factors. For example, lead poisoning from ingested fishing sinkers affects loon health and usually results in death. Boaters or anglers may displace adults from nests causing nest failure, or displace broods from the most productive foraging areas. Loss of quality habitat is the root cause of wildlife problems, not natural predation. Reducing human impacts in loon habitat is the most effective means of helping loons survive and prosper.

      The Montana Loon Society and the Montana Common Loon Working Group have been working to monitor the Montana Common Loon population and reduce human impacts to nesting loons through educational contacts, placing floating signs at nest sites, and voluntary restrictions in nesting and foraging habitat. We can all help by minimizing our impacts on Montana's loons.

      Steve Gniadek
      Columbia Falls
    • ptoomeyjr
      Steve brings up a very worthwhile clarification. That said often these new found imbalances are due to pretty complex reasons. In the example of the eagles
      Message 2 of 3 , Aug 5 9:19 AM
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        Steve brings up a very worthwhile clarification. That said often these new found imbalances are due to pretty complex reasons. In the example of the eagles even if our historic number of Bald Eagles is about right, if their source of food or acreage of habitat is reduced, then they begin feeding in areas in which they have a higher population density OR move onto new areas and begin feeding on newly acquired tastes. Both of these will lead to an imbalance for some species. Bottom line these stories are meant to underscore how it is NOT to lose habitat for any of the species since unexpected results normally will occur.

        Patrick Toomey



        --- In MOB-Montana@yahoogroups.com, "Steve Gniadek" <grayjaybro@...> wrote:
        >
        > Patrick's message about Bald Eagles and seabird predation, and then Dan's comments about Bald Eagles and predation of Common Loon chicks in Montana deserve clarification. I'm not familiar with the situation Patrick presented, though it appears habitat changes were implicated in the increased predation. My concern is that some may erroneously derive from their comments a simplistic cause and effect relationship- a burgeoning Bald Eagle population has resulted in increased eagle predation on loon chicks, in the case of Montana. While that may well be true, there is more to the story.
        >
        > Eagles and loons evolved together, and are only beginning to adjust to burgeoning human populations and our impacts. By stopping the spread of DDT in the environment and through other protective measures humans have helped recover Bald Eagle numbers to approximately historic levels. But human development has eliminated nesting loons from some Montana lakes and continues to encroach on remaining loon territories. Impacts from lakeshore homes and associated activities, fishing, boating and other recreational activities, plus pollution and other environmental contaminants continue to reduce the effectiveness of loon nesting territories. Some nesting lakes are seeing increased competition for remaining territories, not because there are too many loons but because there is less available habitat.
        >
        > So the problem is not that Bald Eagles occasionally prey on loon chicks, that has been going on for millenia, but that human activities make loons less secure and more vulnerable to eagle predation and other factors. For example, lead poisoning from ingested fishing sinkers affects loon health and usually results in death. Boaters or anglers may displace adults from nests causing nest failure, or displace broods from the most productive foraging areas. Loss of quality habitat is the root cause of wildlife problems, not natural predation. Reducing human impacts in loon habitat is the most effective means of helping loons survive and prosper.
        >
        > The Montana Loon Society and the Montana Common Loon Working Group have been working to monitor the Montana Common Loon population and reduce human impacts to nesting loons through educational contacts, placing floating signs at nest sites, and voluntary restrictions in nesting and foraging habitat. We can all help by minimizing our impacts on Montana's loons.
        >
        > Steve Gniadek
        > Columbia Falls
        >
      • Dan Casey
        Steve, Patrick et al: Thank you Steve for telling the rest of the story . I did not mean to oversimplify the complex relationship between habitat, human
        Message 3 of 3 , Aug 5 9:43 AM
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          Steve, Patrick et al:

          Thank you Steve for telling "the rest of the story". I did not mean to oversimplify the complex relationship between habitat, human impacts, and loon and eagle populations; I was merely providing a Montana example paralleling those offered by others. Obviously, eagles have preyed upon both loons (and kittiwakes) for millenia. Fortunately, eagles have apparently come through the population bottleneck that pesticides and other factors induced. Unfortunately, we do not yet know what the future brings for Montana's loon population. In those locations where we are lucky enough to have remaining habitat for both species, some level of predation will continue. Unlike continued human disturbance, habitat alteration and loss, it is a factor that we probably cannot control. Kudos to the CLWG for working on those we can.

          Dan
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