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Re: [CALBIRDS] LIfe and Death at KMHRP.

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  • Bruce Deuel
    The Department of Fish and Game has been plagued for years by die-offs of domestic ducks at parks where people feed them. The usual cause is duck viral
    Message 1 of 5 , Jul 8, 2002
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      The Department of Fish and Game has been plagued for years by die-offs
      of domestic ducks at parks where people feed them. The usual cause is
      duck viral enteritis. It is especially hard on muscovies. It doesn't
      often kill the wild ducks present, but does sometimes and that's been
      the concern - that the disease would get into the wild populations. I
      have never heard of it killing fish, though, so in this case it could be
      something else, or there could be multiple causes. If it does turn out
      to be DVE, there will probably be a public relations nightmare, since
      the only thing that stops the outbreak is to remove all the domestic
      ducks!

      Bruce Deuel
      Red Bluff

      >>> <mjbbirds@...> 07/06/02 11:12PM >>>
      Dear Calbirders,
      I am hoping that you might be able to answer some specific questions
      that
      might help us determine why we are having a continuing bird and fish
      die-off
      at Ken Malloy/ Harbor Regional Park in Harbor City/Wilmington, Los
      Angeles,
      CA.
      First I should note that the park is open, the birding is good and the
      kill
      has to date mostly affected feral and abundant scavenging species.
      There
      have been somewhat sensationalized reports on television and radio, but
      the
      local paper, The Daily Breeze, published a fairly accurate article on
      July 4.
      We are hoping to determine the cause of mortality before/in case it
      spreads
      to include sensitive species or takes any more of our more common
      regular
      species.
      To date, virtually all feral ducks (approximately 260 mallards,
      Muscovies and
      Pekings) have died, as have a large number of coots, most of the gulls
      that
      were feeding at the lake, and most of the larger (all non-native and
      formerly
      stocked) species of fish. Virtually unaffected are feral geese, rock
      doves,
      gadwalls (which are present with juveniles), large numbers of ruddy
      ducks,
      pied-billed grebes (with juveniles), Ardeids, and so on. Today, least
      terns
      were present feeding on Gambusia, swallows of 5 species were flying
      over the
      lake (all but the bank swallow were accompanied by juveniles) and there
      were
      numerous tricolored blackbirds in the Icterid/starling flocks.
      Aside from the rock doves and geese, the affected birds are the ones
      most
      often fed lakeside by park visitors. Huge volumes of bread are brought
      to
      the lake daily, and we believe that bakeries may be dumping their "day
      old"
      bread at the lake as well.
      My specific question is, is there any evidence that toxic molds or
      bacteria
      on bread could be responsible? Perhaps the fish are dying because
      they are
      eating the bread, too, or are scavenging poisoned birds who die on/in
      the
      water?
      We have narrowed the field somewhat, and if another possibility seems
      plausible please let me know.
      The lake is certainly a candidate for eutrophication and the consequent

      mortality, and precedents for this have certainly been set in the
      past.
      Botulism poisoning, chemical poisoning by a toxic substance, and viral
      or
      bacterial pathogens are other possibilities we are considering.
      However, several points argue against any one of these being the
      primary
      cause of mortality (although in combination, they could certainly be
      contributing factors)
      1. the kill has been selective, not affecting fish eaters, species that
      avoid
      humans or even the smaller fish (Gambusia).
      2. The County (LA), Fish and Game and USFWS have taken samples, with
      inconclusive results. However, limited dissolved oxygen and pH testing

      showed no problems. Also arguing against eutrophication is the fact
      that
      there have been no visible signs of an algae bloom, water clarity has
      not
      diminished substantially, there has been no noticeable odor, etc. We
      believe
      that the extensive Ludwigia mats growing along the shoreline do a
      fairly good
      job of removing dissolved nutrients from the water. Water level has
      dropped,
      and no water has been entering the lake for quite a while. With the
      nutrient
      load from the bread, potentially anaerobic conditions would seem to set
      the
      stage for mortality due to lack of dissolved oxygen and/or botulism.
      But it
      seems a eutrophic event would not be nearly as selective and would be
      much
      more evident.
      3. Necropsy results have not been returned to us, and we are not sure
      if and
      when we will get them, but we are told (on the basis of chemical
      tests??)
      that botulism is not involved. My initial suspicion was botulism,
      because a
      park garden supervisor described symptoms of dying birds that were
      consistent with the neurotoxic effects (inability to walk or fly,
      "rubber
      neck" posture, etc.)
      The County Hazmat guys immediately ruled out accidental or intentional
      toxic
      chemical loading of the Lake, on the basis of some of the preceding.
      Intentional poisoning of the bread cannot be ruled out, however.
      Bacterial or viral pathogens that crossed such taxonomic gaps (e.g.,
      ducks,
      coots, gulls and even fish) yet did not affect closely related species

      (gadwalls, ruddy ducks, terns) seem unlikely.
      In any case, any insights, preferably documented rather than anecdotal,
      would
      be appreciated.
      As an end note, I know that individuals in the humane community may be
      upset
      at me for saying this, but without the huge contingent of feral and
      scavenging species, the lake has a quiet and serene beauty that
      provides a
      long-absent sense of wildness there. It is nevertheless important
      that we
      determine the cause of mortality so as to determine how to cope with
      the
      regulatory agencies and public park users regarding park management
      methods,
      and of course, determine whether it will run its course before killing
      other
      species at the park.
      The park is open to the public, and if you desire, please visit on your
      own
      or come to my next public walk there (Sunday July 14, 8 AM, meet in the
      lot
      between Anaheim St. and Vermont) In addition to the surviving species

      mentioned above, there is at least one chat south of the dam and
      hopefully,
      our least Bell's vireos are still present and nesting. Our nesting
      least
      bitterns become more visible in July and August.
      Martin Byhower
      __ /\ __ Martin Byhower, Lomita, CA
      / ___\/ \/___\ Director, BIRDING SOUTHERN CALIFORNIA
      \| |/ Private guiding, & more
      /\ Email: mbinrbc@...
      ///\\\ WEBSITE: http://www.qi-whiz.com/birds


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    • Charles Bragg
      ... Anyone wanting to read about DVE can see our March 1994 newsletter at http://home.att.net/~cgbraggjr/v17n7.htm The duck symptoms are close to what
      Message 2 of 5 , Jul 8, 2002
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        At 08:34 AM 7/8/2002 -0700, Bruce Deuel wrote:
        >The Department of Fish and Game has been plagued for years by die-offs
        >of domestic ducks at parks where people feed them. The usual cause is
        >duck viral enteritis.

        <snip>

        Anyone wanting to read about DVE can see our March 1994 newsletter at http://home.att.net/~cgbraggjr/v17n7.htm The duck symptoms are close to what is happening at Harbor Park, but the species dying and living are mystifying.

        The articles in the newsletter cover all sides of the enormous controversy over analysis and treatment in the Venice Canals in Spring 1993. It was nasty.
        Here is the clinical description of DVE:

        DUCK PLAGUE (DUCK VIRUS ENTERITIS)
        Cause: A herpes virus.
        Host: Only ducks, geese, and swans. There is variation in species susceptibility to this virus. For example, blue-winged teal are most susceptible, while pintails are least.
        Transmission: Direct contact with affected birds or contaminated surfaces, ingestion of food or water contaminated with infected feces or oral discharges, inhalation of viral particles and vertical transmission from female to forming egg.
        Clinical Signs/Field Signs: Rapid death in previously healthy appearing birds. Sick birds are seldom seen but may seek cover and have ruffled feathers, extreme thirst, loss of awareness, droopy head and wing, inability to fly, sensitivity to light, blood around the vent or bill, and prolapsed penis.
        Lesions: Bands or disk shaped areas of hemorrhagic or yellow/tan tissue distributed in or on the esophagus, intestinal wall and cloaca. Blood in the digestive tract. Small white spots on the liver and hemorrhages on the heart.


        -- Chuck


        ========
        Chuck Bragg, Pacific Palisades, CA
        Santa Monica Bay Audubon Society:
        http://smbas.cjb.net
        ========
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