SUMMARY OF BIRDS KILLED BY A HARMFUL ALGAL BLOOM ALONG
THE SOUTH WASHINGTON AND NORTH OREGON COASTS DURING
OCTOBER 20091
ELIZABETH M PHILLIPS, JEANNETTE E ZAMON, HANNAHROSE M NEVINS, CORINNE M GIBBLE,
REBECCA S DUERR, AND LAUREN H KERR
NORTHWESTERN NATURALIST
92:120–126
AUTUMN 2011
SUMMARY OF BIRDS KILLED BY A HARMFUL ALGAL BLOOM ALONG
THE SOUTH WASHINGTON AND NORTH OREGON COASTS DURING
OCTOBER 20091
ELIZABETH M PHILLIPS, JEANNETTE E ZAMON, HANNAHROSE M NEVINS, CORINNE M GIBBLE,
REBECCA S DUERR, AND LAUREN H KERR
Key words: Akashiwo sanguinea, demography, harmful algal bloom, Oregon, plumage
fouling, seabird, Washington
Seabirds are known to be vulnerable to
biotoxins produced by harmful algal blooms
(HABs). The ingestion of prey contaminated
with biotoxins such as domoic acid can cause
disorientation, seizures, morbidity, and mortality (Work and others 1993). During November
2007 in Monterey Bay, California, an unprecedented stranding of live and dead seabirds
highlighted plumage fouling as an emerging
mortality factor during harmful algal bloom
(HAB) events. The fouling agent was a proteinaceous foam derived from the cellular breakdown of the dinoflagellate Akashiwo sanguinea.
This foam coated seabird plumage in a manner
similar to fouling by petroleum oil (Hartung
1967; McEwan and Koelink 1973; National
Research Council 1985), causing waterlogging,
hypothermia, morbidity, and mortality in the
California birds (Jessup and others 2009).
During late October 2009 along the southern
Washington and northern Oregon State coasts,
algal blooms caused another seabird plumage
fouling event, where several bird species were
coated in a foam surfactant. Water and feather
samples confirmed that this dinoflagellate bloom
was also A. sanguinea (Dr. Raphael Kudela,
1
We dedicate this manuscript to the men and women
at US Coast Guard Air Station Sacramento, who
donated their time and use of the C-130 Hercules
aircraft to transport seabirds. This same Coast Guard
aircraft crashed off the coast of San Diego, CA on 30
October 2009, within days of responding to the HAB
event documented in this manuscript. All hands on
board that aircraft were lost. We honor their memory
and service.
120
University of California Santa Cruz, Santa Cruz,
CA, pers. comm.). Du and others (in press)
describe the conditions that facilitated the A.
sanguinea bloom off the Oregon coast and
propose that the source of the bloom was
southward transport of cells from a massive
September bloom that first occurred off the
Washington coast. Similar to the 2007 California
event, the foam produced by the WashingtonOregon bloom reduced the waterproofing of
birds’ plumage, causing hypothermia in individual birds and leading to the stranding of
hundreds of debilitated live and dying seabirds
on public beaches.
During this event, volunteers and federal,
state, and local resource management agencies
collected as many birds as possible for rescue
and rehabilitation from the Long Beach Peninsula, WA; Fort Stevens State Beach, OR; and
Cannon Beach, OR. Most of the birds collected
were initially delivered to the Wildlife Center of
the North Coast (WCNC) rehabilitation facility
in Astoria, OR, where volunteers observed that
birds were cold, weak, stressed, and starving.
Due to the magnitude of this event, the WCNC
facility was quickly overwhelmed by hundreds
of collected seabirds, which included Common
Loons (Gavia immer), Common Murres (Uria
aalge), Pacific Loons (G. pacifica), Red-throated
Loons (G. stellata), Surf Scoters (Melanitta perspicillata), and Western and Clark’s Grebes
(Aechmophorus occidentalis and A. clarkii). Birds
were subsequently transferred to facilities that
were better equipped to handle large numbers
of seabirds for rehabilitation, including the
International Bird Rescue Research Center
(IBRRC) in Cordelia, CA (n 5 479 birds), and
Progressive Animal Welfare Society (PAWS) in
Lynnwood, WA (n 5 125). Some birds responded well to supportive care and were eventually
AUTUMN 2011
GENERAL NOTES
121
FIGURE 1. Map of coastal US and Canada and panel showing the observation site at North Head Lighthouse
in Washington State.
released. However, many birds were too physiologically compromised and did not survive.
We summarize information from necropsies
of birds that were collected dead from beaches
or that died during rehabilitation in the Oregon
(WCNC) and California (IBRRC) facilities. A
total of 308 seabirds were examined at 2
facilities: NOAA Fisheries Point Adams Research Station, Hammond, OR (n 5 100; NOAA)
and California Department of Fish and Game
Marine Wildlife Veterinary Care and Research
Center, Santa Cruz, CA (n 5 208; MWVCRC).
We identified species of all carcasses and
recorded information on morphometrics, age,
sex, and body condition. Tissue samples from
skeletal muscle, feathers, liver and in some
cases, stomachs, were collected and stored
frozen at MWVCRC.
Species composition of the examined birds
was compared with data from local monthly
marine bird surveys, which have been conducted since 2004 at the North Head Lighthouse in
Washington State (UTM: Zone 10, 417191.55E,
5127731.94N, NAD1983; elevation 59 m above
sea level). The survey site is located at the
southern end of the Long Beach Peninsula,
within the area where large numbers of birds
stranded during the HAB event (Fig. 1). On
each survey day, birds sitting on the water were
counted every half hour between sunrise and
15:30 in the same 1.9-km2 nearshore sector from
the surf to 1.4 km offshore of the lighthouse.
To determine sex and approximate age of the
seabirds killed during this event, we identified
and assessed gonad maturity (length and width
of gonad in both sexes, diameter of largest
follicle and oviduct development in females)
and recorded the presence or absence of the
bursa of Fabricius, a lymphatic gland that is
largest in 1st-year birds and atrophies with age
and sexual maturation (Broughton 1994). When
present, bursal length and width were recorded.
We also noted plumage type (basic, transitional,
alternate) and molt of the primaries and body
feathers. We quantified body condition by
measuring body mass as well as assigning each
bird a numerical condition score based upon
examination of body fat and muscle tissue.
122
NORTHWESTERN NATURALIST
92(2)
TABLE 1. Total number (n), sex ratio, and estimated age of seabirds (listed alphabetically) examined at NOAA
and MWVCRC following Washington–Oregon harmful algal bloom event in October 2009.
Age Estimate
n
Sex (M:F ratio)
Adult
Immature
Unknown
Clark’s Grebe
Common Loon
Common Murre
Pacific Loon
Red-Throated Loon
Surf Scoter
Western Grebe
Species
3
16
82
3
116
2
86
0.5:1
0.4:1
3.8:1
0.5:1
1.1:1
1.0:1
0.8:1
2
14
56
2
93
1
42
1
2
21
12
36
5
1
11
1
8
Total
308
210
72
26
Because birds in deteriorating physiological
condition metabolize fat reserves before metabolizing muscle proteins, this body condition
score measures the relative availability of fat
and muscle reserves (van Franeker 2004). We
scored subcutaneous and intestinal fat between
zero (poor condition; no fat) to three (good
condition; very fat). When present, we measured subcutaneous fat depth in millimeters
over the breast muscle to the right of the keel.
Similarly, the condition of the breast muscle
(pectoralis-supracoracoideus complex) was
scored between zero (poor condition; strongly
emaciated, muscle significantly atrophied below keel-line) to three (good condition; muscle
at or above keel-line). Following van Franeker
(2004), we then summed the three condition
scores into an overall body condition index.
During the examination we also noted any
external injuries to wings, bill, or feet.
Red-throated Loons, Western Grebes, and
Common Murres represented the greatest proportion of examined birds (92%, n 5 284,
Table 1). The majority of birds examined were
adults (68%, n 5 210), and 23% were classified
as immature (n 5 72). Eight percent (n 5 26)
were classified as unknown age, but were most
likely immature or sub-adult birds. With the
exception of Red-throated Loons, the species
composition of birds examined was proportionally similar to that typically observed in local
nearshore marine bird surveys (Fig. 2). Western
Grebes are the dominant species observed in fall
and winter, but loons, murres, and scoters are
also regularly observed.
There were no apparent differences in the sex
ratios of any of the seabird species examined,
with the exception of Common Murres. Nearly
4 times more male than female murres were
affected by this event (Table 1), and 68% were
adults. Twenty-six percent of the murres examined were immature birds, and most of these
were hatch-year chicks. The bias in murre sex
ratio is explained by their breeding ecology:
adult males accompany newly fledged chicks to
sea and associate with the chick throughout the
fall and winter season before leaving the chick
to forage on its own (Scott 1990). Similar malebiased ratios in murres have been observed in
other fall mortality events, including gill-net
fisheries bycatch in California (Nevins 2004).
All examined birds were moderately to
severely emaciated, with a high frequency of
pectoral muscle atrophy and virtually no
subcutaneous or internal fat (Table 2). On
average, all birds examined were 31% below
normal body mass, indicative of starvation
stress. Although body condition indices improved with duration of rehabilitation, and the
range of values for overall body condition index
was 0 to 7, the median value for all species was
within the critically to mortally emaciated range
(0 to 2). With the exception of birds that were
force-fed fish or given nutritional tube feedings
while in rehabilitation, most birds had empty
stomachs or only stones in their stomachs.
Numerous Western Grebes had moderate to
significant dry feather balls present in their
ventriculi, a common observation in grebes,
which are known to eat their feathers (Ehrlich
and others 1988). In healthy grebes these feather
balls are moist and saturated with digesta.
Many of the birds examined had generalized
pallor of muscle tissue and organs, as well as
evidence of urate stasis in the kidneys, ureters,
and cloacae, suggestive of dehydration. In
particular, 53% of Red-throated Loons had
distended cloacae, perhaps related to the build
AUTUMN 2011
GENERAL NOTES
123
FIGURE 2. General taxonomic composition of seabirds observed from the North Head Lighthouse in
Washington State. Proportions were calculated from mean maximum daily counts of sitting birds for each
month from August 2004 to December 2009.
up of crystallized urates. Similarly, 50% of
Western Grebes and 16% of Common Murres
had distended cloacae. Additionally, we commonly found gastrointestinal hemorrhage, another indicator of physiological stress.
Grebes, murres, and loons are essentially
flightless during their primary molt, which
occurs soon after their arrival in wintering
habitat along the coasts of Washington and
Oregon. This makes them more susceptible to
oiling or plumage fouling events due to lack of
mobility. Molting birds are also likely under
greater nutritional stress than non-molting
birds. Fifty-eight percent of the birds were
TABLE 2. Summary of body condition measures for all seabird species (listed alphabetically) examined at
NOAA and MWVCRC following Washington–Oregon harmful algal bloom event in October 2009.
Species
Mean body
mass (g)
Percent
below
normal
massa
Clark’s Grebe
Common Loon
Common Murre
Pacific Loon
Red-throated Loon
Surf Scoter
Western Grebe
731.7
2673.4
657.3
1358.3
1249.0
700.0
847.2
47.7
34.8
33.6
20.1
10.8
26.3
43.5
a
Normal body mass is based on Sibley (2000).
Mean
fat depth
(mm)
Median
muscle
score
(0–3)
Median
subcutaneous
fat score
(0–3)
Median
intestinal
fat score
(0–3)
Median
overall body
condition
(0–9)
0.0
0.2
0.0
0.0
0.0
0.0
0.0
1
1
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
1.0
1.5
0.0
0.0
0.0
0.0
0.0
124
NORTHWESTERN NATURALIST
undergoing molt of the primary feathers, and
almost all of the birds examined were in winter
or basic plumage. Because many of these birds
were actively undergoing molt, sensitive blood
feathers were damaged during the stranding
event. Injuries to primary feathers and wings
were documented in the three most common
species: 24% of Red-throated Loons had moderate to severe injuries to their wings; 9% of
Western Grebes and 4% of Common Murres
also had wing injuries. These injuries most
likely occurred during beach stranding or
during active avoidance of humans or predators
while stranded. It is also possible some injuries
occurred during capture and handling. Additional wing injuries noted during the necropsies
included broken or damaged primaries and
abrasions along the carpal joints.
Reports from rescue organizations indicated
that Red-throated Loons and Western Grebes
were the most difficult to capture, and were
therefore the most likely to be left on beaches.
Many loons travelled on land into residential
and business neighborhoods, up to a half-mile
from the beach, where cars struck some of the
birds. Loons and grebes are fully aquatic species
that never come ashore, and their bone structure
is not designed to support their body weight on
land. Therefore, these species are particularly
vulnerable to injury caused by abnormal weight
bearing on leg and keel bones. Most foot and
keel injuries were likely attributable to bird
movement from sea to town (Sharnelle Fee,
Wildlife Center of the North Coast, Astoria, OR,
pers. comm.). The primary reason birds in
rehabilitation were euthanized was due to the
severity of leg or keel injuries. Fifty-six percent
of Red-throated Loons necropsied at MWVCRC
had severely edematous or necrotic foot webbing and 45% had four or more fractured or
luxated terminal toe joints. Thirty-one percent
of loons had significant keel pressure sores.
Additionally, 13% of Common Loons and 5% of
Red-throated Loons and Western Grebes had
moderate to severe injuries to their bills, which
included broken bill tips and fractured mandibles. Bill injuries also likely occurred during
stranding, especially if the birds were weakened
and traveling over hardened surfaces. Proper
handling of birds, including the use of containers with narrow bar spacing to prevent birds
from sticking long bills or necks through the
92(2)
bars, should reduce the likelihood of bill injury
during capture and transport.
The similarity of species composition between
local survey data and the HAB event suggests
that impacts of this mortality event were
nonselective in the nearshore environment.
The higher proportion of Red-throated Loons
affected by the HAB is most likely explained by
the temporal and spatial extent of the HAB
event coinciding with a pulse of migrating
loons. The seabirds affected are also those
typically affected by winter oil spills, including
nearshore species such as loons and grebes
(Hampton and others 2003). Jessup and others
(2009) noted that most foam observed during
the 2007 California event occurred in the surf
zone, where turbulent mixing of seawater by
wave action likely created the foam. However,
there may be unobserved impacts on other
species that did not strand on the beaches,
including seabirds that typically occur further
offshore and may not be regularly detected in
nearshore or beach surveys. For example,
Jessup and others (2009) noted that pelagic
species including the Northern Fulmar (Fulmarus glacialis) seemed to have encountered the
foam further offshore, where foam accumulated
along frontal edges of the bloom.
Similar HAB events may be increasing in
frequency (Parsons and others 2006; Jessup and
others 2009). Because such events could be
linked to regional climate change (Cloern and
others 2005; Moore and others 2009), coastal
development, or changes in nearshore water
chemistry (Paerl 1997; Sellner and others 2003),
it is important to accurately document the
timing, geographic extent, duration, and ecosystem impacts. Past studies have found that
many HAB-associated seabird mortality events
are underreported (Shumway and others 2003).
Thus, a rapid, coordinated response by local
and regional wildlife rehabilitation groups,
biologists, and natural resources agencies is
required, and strandings of particularly sensitive or threatened species are important to
document. For example, the preponderance of
mature birds affected by the 2009 event may be
particularly important for Red-throated Loons,
which face a multitude of conservation threats
on breeding grounds (Barr and others 2000). In
conjunction with rescue efforts during a HAB
event, collecting data on the species composi-
AUTUMN 2011
GENERAL NOTES
tion and estimated number of birds affected, as
well as the spatio-temporal impact of the event,
will be required if natural resource agencies are
to determine the demographic effects of such
events on marine bird populations. This latter
type of scientific data collection typically falls
outside the normal focus and capabilities of
wildlife rescue or rehabilitation facilities.
The impacts of HAB events on seabird
populations are not well known, and if the
frequency or magnitude of HAB events is
increasing, HABs could represent another mortality source of conservation concern. Most of
the species affected by this event face other
conservation threats including oil spills, habitat
degradation, pollution, fisheries interactions,
and introduced predators at their colonies.
Although response networks are in place for
documenting anthropogenic events such as oil
spills, there are not analogous response networks in place for documenting unusual die-off
events, including HABs. We recommend that
agencies build upon successful oil-spill response network models and provide support
for developing networks and establishing common data collection protocols. In the meantime,
we encourage continuing regional cooperation
to document any similar events which may
occur in the future.
Acknowledgments.—We thank the many staff and
volunteers at regional rehabilitation centers for their
efforts to collect, transport, and rehabilitate birds and
to provide specimens for necropsy, including: the
Wildlife Center of the North Coast (S Fee), the
International Bird Rescue Research Center (J Holcomb), the Oiled Wildlife Care Network (M Ziccardi)
and the members of the US Coast Guard who assisted
with transporting birds (Districts 11 and 13). D
Jacques (Pacific Eco Logic) responded rapidly to
collect specimens for necropsy during this unusual
mortality event; we are also grateful for her assistance during necropsies at NOAA. We thank all
volunteers who helped with necropsies: S Hinton and
M Morrow at NOAA, and F Batac, E Donnelly, B
Hoover, A Ford, A Wells, and C Young at MWVCRC.
Necropsy work and report compilation were supported by funding from NOAA Northwest Fisheries
Science Center, Office of the Science Director (to J
Zamon), Moss Landing Marine Laboratories (to J
Harvey), and the California Department of Fish and
Game, Marine Wildlife Veterinary Care and Research
Center (to D Jessup). W Peterson and 2 anonymous
reviewers provided helpful comments on this manuscript.
125
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NORTHWESTERN NATURALIST
92:239
WINTER 2011
ERRATUM:
The following is a correction to a GENERAL
NOTE published in the Autumn 2011 (Volume 92
Number 2) issue titled SUMMARY OF BIRDS
KILLED BY A HARMFUL ALGAL BLOOM
ALONG THE SOUTH WASHINGTON AND
NORTH OREGON COASTS DURING OCTOBER 2009 by Elizabeth M Phillips, Jeanette E
Zamon, Hannahrose M Nevins, Corinne M
Gibble, Rebecca S Duerr, and Lauren H Kerr.
Paragraph 3 on page 120 (right column),
beginning with the 4th sentence, should have
been corrected to:
‘‘Of the 792 total birds collected during this
event, 597 were subsequently transferred to
facilities that were better equipped to handle
large numbers of seabirds for rehabilitation,
including the International Bird Rescue Research
Center (IBRRC) in Cordelia, CA (n 5 479 birds)
and Progressive Animal Welfare Society (PAWS)
in Lynnwood, WA (n 5 118). Some of the
collected birds responded well to supportive care
and were eventually released (n 5 344). Many
birds (n 5 448), however, were too physiologically compromised and did not survive.’’
239