dead ducks collected at Eagle River Flats. For
Racine, C.H., M.E. Walsh, B.D. Roebuck, C.M.
dabbling ducks, P4 particle size is not as impor-
Collins, D.J. Calkins, L.R. Reitsma, P.J. Buchli,
and G. Goldfarb (1992) White phosphorus poi-
tant as the dose ingested. For predators, the P4
soning of waterfowl in an Alaskan salt marsh.
contents of the entire digestive tract is important
Journal of Wildlife Diseases, 28(4): 669673.
for assessment of the risk of poisoning.
The cause of the yearly death of an estimated
1000 to 2000 migrating dabbling ducks (Anas sp.)
Roebuck, B.D., M.E. Walsh, C.H. Racine, L.R.
and 10 to 50 swans (Cygnus buccinator and C.
Reitsma, B.B. Steele, and S.I. Nam (1994) Preda-
columbianus) has remained a mystery for the last 10
tion of ducks poisoned by white phosphorus:
years in Eagle River Flats (ERF), a 1000-ha estua-
Exposure and risk to predators. Environmental
rine salt marsh near Anchorage, Alaska, used for
Toxicology and Chemistry, 13(10): 16131618.
artillery training by the U.S. Army. We have gath-
White phosphorus (P4) has been identified as
ered evidence that the cause of this mortality is the
the cause of mortality for dabbling ducks and
highly toxic incendiary munition white phospho-
swans at an estuarine salt marsh in Alaska. Pre-
rus (P4). The symptoms of poisoning we observed
dation of ducks poisoned by P4 was monitored to
in wild ducks included lethargy, repeated drink-
assess the extent and range of predator exposures
ing, and head shaking and rolling. Death was pre-
to P4. Avian tissues were analyzed for P4 by gas
ceded by convulsions. Farm-reared mallards
chromatography. We observed that both sick and
dosed with white phosphorus showed nearly
dead dabbling ducks were common prey of bald
identical behavioral symptoms to those of wild
eagles (Haliaeetus Ieucocephalus), herring gulls
ducks that became sick in ERF. White phosphorus
(Larus argentatus), and common ravens (Corvus
does not occur in nature but was found in both the
corax). Frank signs of P4 intoxication attracted
sediments where dabbling ducks and swans feed
predators and rendered the ducks easy prey. White
and in the gizzards of all carcasses collected in
phosphorus was found in the tissue remains of
ERF. We hypothesize that feeding waterfowl are
ducks that had been preyed upon, thus providing
ingesting small particles of the highly toxic, incen-
positive evidence that predators were exposed to
diary munition P4 stored in the bottom anoxic sed-
P4. Although P4 varied widely among individu-
iments of shallow salt marsh ponds.
als, P4 was generally highest in the gizzard con-
tents followed by fatty tissues such as fat depots
and the skin. White phosphorus was identified in
Roebuck, B.D., S.I. Nam, D.L. MacMillan, K.J.
Baumgartner, and M.E. Walsh (1998) Toxicology
fatty tissues of one eagle and in one herring gull
of white phosphorus (P4) to ducks and risk for
egg, thus providing direct evidence of absorption
their predators: Effects of particle size. Environ-
of P4 by predators.
mental Toxicology and Chemistry, 17(3): 511518.
Particles of white phosphorus (P4) in pond sed-
Sparling, D.W., and N.E. Federfoff (1997) Sec-
iments at Eagle River Flats, Alaska, U.S.A., a mili-
ondary poisoning of kestrels by white phospho-
tary artillery range are acutely toxic to dabbling
rus. Ecotoxicology, 6: 239247.
ducks and swans. We determined if toxicity of P4
Since 1982, extensive waterfowl mortality
to ducks varied by its form (i.e., dissolved or par-
attributable to white phosphorus (P4) has been
ticulate) or particulate size. Residual P4 in the
observed at Eagle River Flats, a tidal marsh near
digestive tract of ducks was measured to assess
Anchorage, Alaska. Ducks and swans that ingest
risks posed to predators and scavengers of ducks.
P4 pellets become lethargic and may display
Farm-reared mallards were treated with 12 mg
severe convulsions. Intoxicated waterfowl attract
P4/kg body weight, either dissolved in oil, or as
raptors and gulls that feed on dead or dying
numerous small, or one to two large particles. At
birds. To determine if avian predators can be
the first major convulsion, ducks were euthanized
affected by secondary poisoning, we fed Ameri-
and the quantity and location of P4 in the digestive
can kestrels (Falco sparverius) 10-day old domestic
tract were determined. These data were compared
chickens that had been dosed with white phos-
to data from dead ducks collected from the artil-
phorus. Of 15 kestrels fed intact chicks with a
lery range. Dissolved P4, and small or large parti-
pellet of P4 implanted in their crops, 8 died within
cles of it produced similar acute toxicity. Residual
7 days. Of 15 kestrels fed chicks that had their
P4 in digestive tracts was greatest in ducks treated
upper digestive tracts removed to eliminate any
with small particles and was as great as 3.5 mg P4.
pellets of white phosphorus, 3 also died. Haemat-
Similar quantities of residual P4 were found in
ocrit and haomoglobin in kestrels decreased,