Mass die-off of Magellanic penguins seen during 2019 heat wave

Date:
January 4, 2022
Source:
University of Washington
Summary:
In 2019, researchers witnessed the consequences of an extreme
heat event at Punta Tombo in Argentina, one of the world's largest
breeding colonies for Magellanic penguins. On Jan. 19, temperatures
at the site spiked in the shade to 44 C, or 111.2 F, killing at
least 354 penguins. Nearly three-quarters of the penguins that
died were adults, many of which likely died of dehydration, based
on postmortem analyses.



FULL STORY ==========================================================================
In June 2021, an unprecedented heat wave hit the Pacific Northwest and
Canada, killing an estimated 1,400 people. On June 28, Seattle reached
108 F -- an all- time high -- while the village of Lytton in British
Columbia recorded Canada's highest-ever temperature of 121.3 F on June
29, the day before it was destroyed by a heat-triggered wildfire.


========================================================================== Climate change is expected to bring more such extreme heat events
globally, with far-reaching consequences not just for humans, but for
wildlife and ecosystems.

In 2019, University of Washington researchers witnessed this in
Argentina at one of the world's largest breeding colonies for Magellanic penguins. On Jan.

19, temperatures at the site in Punta Tombo, on Argentina's southern
coast, spiked to 44 C, or 111.2 F, and that was in the shade. As the
team reports in a paper published Jan. 4 in the journal Ornithological Applications, the extreme heat wave killed at least 354 penguins, based
on a search for bodies by UW researchers in the days following the record
high temperature.

"This extreme event fell near the tail end of the breeding season
for Magellanic penguins, so it killed a large number of adults, as
well as chicks," said lead author Katie Holt, a UW doctoral student in
biology. "It's the first time we've recorded a mass mortality event at
Punta Tombo connected to extreme temperatures." The Jan. 19 heat wave
was the highest temperature the researchers have ever recorded at Punta
Tombo, where UW teams have been studying Magellanic penguins since 1982
under co-author P. Dee Boersma, a UW professor of biology.

Temperatures at the site during the breeding season typically rise from
the 50s F to the low 100s F. In a past season, researchers had previously recorded a shade high of 43 C, or 109.4 F, but that older record was
not associated with a mass die-off of penguins, according to Holt.

The extreme heat on Jan. 19 affected adults and chicks differently. Nearly three-quarters of the penguins that died -- 264 -- were adults, many of
which likely died of dehydration, based on postmortem analyses conducted
by the UW researchers. They found 27% of adult penguin corpses along
paths heading out of the breeding colony to the ocean, where they
could get a drink -- penguins have glands that can filter salt out of
the water. A journey from the colony to the ocean can stretch up to one kilometer and, at its longest, might take an adult Magellanic 40 minutes
to complete. Dead adults were often found on their stomachs with their
feet and flippers extended and mouth open, a common panting and cooling
pose for Magellanic penguins.



==========================================================================
Some sections of Punta Tombo, where thousands of Magellanic penguins
gather to breed each austral spring and summer, fared worse than
others. In the central section of the colony, about 5% of adults
perished. But other sections saw few or no fatalities, indicating that microclimates and access to the ocean, as well as individual health and nutrition, may have influenced survival rates.

UW researchers have documented past mass mortality events at Punta Tombo
linked to severe rainstorms that killed primarily chicks, including
one year where deluges killed 50% of the colony's recently-hatched
offspring. The 2019 heat wave is a particular concern because it led to
the loss of a large number of adults in a single event, according to Holt.

"Any mass die-off like this is a concern," said Holt. "But what is most concerning about heat-death mortality is that it has the potential to kill
a lot of adults. The population viability of long-lived seabirds -- like Magellanic penguins -- relies on long lifespans. Adult Magellanic penguins
can live more than 30 years, so they typically have many opportunities to successfully raise chicks. If we're losing large numbers of adults from
a single event like this, that's a major concern." Based on examination
of a subset of corpses, at least 8 out of 10 of the adults that died
were males. That likely reflects the high prevalence of male Magellanic penguins at Punta Tombo -- roughly three males to every female - -
rather than a differential survivability in extreme heat. The colony's
skewed sex ratio has grown over time. Research by Boersma's group shows
that adult females are less likely to return to Punta Tombo to breed,
likely because they have more trouble finding enough food in the open
ocean outside the breeding season. This has likely contributed to an
overall decrease in the size of the colony since the late 1980s.

The remaining 90 fatalities from the Jan. 2019 heat wave were
chicks. Based on postmortem analyses, the chicks that perished tended to
be well fed and did not show signs of dehydration. They may have died
because, with full bellies and small bodies, they could not regulate
their body temperatures properly in the extreme heat, according to Holt.

Climate change is expected to produce more extreme weather events of all
types globally, though effects will vary by locality. The consequences
of this heat wave, though grim, also show scientists the limits that
some species can endure.

Boersma is founder of the UW-based Center for Ecosystem Sentinels,
which studies Magellanic penguins and other species that are seen as
key indicators of ecosystem health.

"Penguins could have the ability to cope, like moving breeding
sites," said Holt. "But it will take time to investigate whether those adaptations are effective." The research was funded by the Wildlife Conservation Society, Exxon-Mobil Foundation, the Pew Fellows Program in
Marine Conservation, the Disney Worldwide Conservation Fund, the Chase Foundation, the Cunningham Foundation, the MKCG Foundation, the Offield Foundation, the Peach Foundation, the Thorne Foundation, the Tortuga Foundation, the Kellogg Foundation and the Wadsworth Endowed Chair in Conservation Science at the UW.

========================================================================== Story Source: Materials provided by University_of_Washington. Original
written by James Urton. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Katie A Holt, P Dee Boersma. Unprecedented heat mortality of
Magellanic
Penguins. Ornithological Applications, 2022 DOI: 10.1093/ornithapp/
duab052 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220104163452.htm
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