From: J.M.Spencer@newcastle.ac.uk (Jonathan Spencer)
Subject: lead poisoning in raptors
Organization: University of Newcastle upon Tyne, UK, NE1 7RU
Date: 21 Jul 92 11:01:04 CDT
Summary: symptoms & treatment
Originator: hunting@osnome.che.wisc.edu
Keywords: hawks, falcons, raptors, poisoning


   Some time ago (six months?) there was a discussion on the subject
the risk of lead poisoning in raptors posed by the use of fragmenting
rifle ammunition vs. the [believed] lower risk of lead poisoning posed
by the use of FMJ ammunition. The following article, which appeared in
the April 1987 Newsletter of The British Falconers' Club, is of
relevance here. It is reproduced w/o the Editor's permission, but
seeing as I am an Officer of the Club, I don't think there's any need.
Comments in square brackets are mine.

   "It has been brought to my attention that over the last six months
a lot of birds have been dying of lead poisoning. I think that a few
points should be raised to help falconers avoid this condition.

   Firstly, lead poisoning is caused by lead shotgun pellets being
eaten by birds that have been fed wild caught food. The animal could
have been shot prior to being caught [by your hawk] to be fed [to that
hawk], so anything [taken from the wild] has to be suspect. The lead
stays in the gizzard where acid juices dissolve the lead and allow it
to be absorbed into the body. The matter is worsened if day old chicks
are fed afterwards as the chick hair seems to be unable to incorporate
the lead [in order] to cast it. Lead pellets in the muscle tissue of
birds will not give the shot bird lead poisoning, as insoluble lead
salts are formed round it that stop it from being absorbed.

   Secondly, the symptoms of lead poisoning are easy to spot and
develop rather slowly; that is over a couple of days rather than a
couple of hours. The bird starts to look lethargic and its eyes tend
to half close a lot. It starts to go off its food and its intestinal
activity decreases which probably accounts for its lack of ability to
cast up the [lead] pellet. Any food that is fed tends to stay in the
crop. It [the bird] then starts to become weaker and has to sit down.
The most classical sign is that at least half the birds I have seen
sit down on the hocks and 'hold hands with themselves'. I have not
seen any other disease cause this, so it is a sign worth remembering.
Finally, they start to have fits. These are brought on more when you
pick up the bird, the bird will become rigid and it 'vibrates's

   Thirdly, lead poisoning is easy to confirm as a diagnosis. An X-ray
of the bird will show the lead pellet(s) in the gizzard. I have seen
one case of lead poisoning that was caused by eating a lead based
metal primer which got on to the feathers when the bird bated [leapt
about] inside a rusty van. The bird then preened it off and it got
into the gizzard that way. This was confirmed by taking the urinary
portion of the mutes [excrement] and having the lead levels analysed.
The small particles of metal were still visible on x-ray, however, but
I did not believe it at first!

   Finally, treatment is relatively straightforward. There is an
injection to remove the lead from the bloodstream. I normally
anaesthetise the bird and give it a dose of Calcium Di-sodium
Versenate intraveneously mixed into the standard dilution as for any
other animal. The anaesthetic is a necessity if the bird is having a
fit or struggling as there is usually a large volume of fluid to
inject. I then usually remove the lead surgically by opeing the
gizzard through an abdominal incision. Sometimes the crop has to be
empotied as well if the bird has been force-fed as the food starts to
putrify. Post-operative fluids and anti-biotics are given. The lead
poisoning anti-dote is given daily until the symptoms go and the bird
is feeding itself. This usually takes up to five days.

  I have seen about twenty cases of lead poisoning and fortunately
they have all made a complete recovery, but it does require falconers
to to seek veterinary advice promptly. I do not think any veterinary
surgeon is going to mind his client volunteering that his birds could
have ingested lead, as I said before, it is easy to confirm or rule
out as a diagnosis.

Nigel Harcourt-Brown BVSc MRCVS "

A couple of comments of my own.  By far the most shooting that takes
place in this country is with shotguns. Some falconers use shotguns to
secure food for their hawks, and I know from experience that even on a
pale fleshed animal like a rabbit that it is impossible to be certain
that all pellets have been removed. (It's far worse on a dark fleshed
animal like a fox.) Some falconers, including myself, use .22LR rifles
to head shoot rabbits. This method leaves no lead in the hawk's food.
Centre-fire rifles in Britain are subject to much tighter control and
are far less common than in other countries. Thus those mammals which
are shot with centre-fire rifles are VERY unlikely to be fed to hawks.
Hence Nigel is concerned mostly with lead poisoning cause by shotgun
pellets.

Hawks use grit in their gizzards to grind up the bones they swallow.
So it is quite possible that lead shot is intentionally retained by
the hawk's body. But I recall someone (Toby Bradshaw wasn't it?)
saying that his hawks actually cast up lead shot. Nigel suggests that
day old chicks prevents the hawks from casting up the lead: what food
enables your hawks to cast the shot?

Anyone wanting to contact Nigel can do so by writing to him at Crab
Lane, Harrogate, North Yorkshire, England or by telephoning +44 423
508 945 or +44 423 884 074.

-- Jonathan

Mail  : Computing Lab., University of Newcastle-upon-Tyne, NE1 7RU, England
ARPA  : J.M.Spencer%newcastle.ac.uk@cs.ucl.ac.uk
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