mass mortality event

In March 1904, 1.5 million migrating birds died in Minnesota and Iowa during a strong snowstorm. According to The Guardian, this was the largest avian mortality event on record in the region. Records of MMEs have been kept since the 1880s. MMEs of this size are rare, however, and few before or since have been as big as the 1904 event. According to the records, MMEs "are always associated with extreme weather events such as a drop in temperature, snowstorm or hailstorm".

In 1984, about 10,000 caribou of the George River caribou herd—one of Canada's migratory woodland caribou herds—drowned during their bi-annual crossing of the Caniapiscau River when the James Bay Hydro Project flooded the region.{{Citation|last=Berkes|first=F.|year=1988|title=The intrinsic difficulty of predicting impacts: Lessons from the James Bay hydro project|journal=Environmental Impact Assessment Review |volume=8 |issue=3|pages=201–220|doi=10.1016/0195-9255(88)90067-4}}

In 1988, the deaths of 20,000 harbour seals in the North Sea were found to be caused by phocine distemper virus.

Ten years later, two strains of bacteria were implicated in the deaths of approximately 1,600 New Zealand sea lions.

On Marion Island in 2007, some 250–300 adult male subantarctic fur seals died in a two-week period. It was suggested, though not proven, that this gender-biased mortality was caused by Streptococcus sanguinis, a bacterium carried by the house mouse, an alien species accidentally introduced to the island in the 1800s.{{Cite journal|last1=de Bruyn|first1=P. J. Nico|last2=Bastos|first2=Armanda D. S.|last3=Eadie|first3=Candice|last4=Tosh|first4=Cheryl A.|last5=Bester|first5=Marthán N.|last6=Hansen|first6=Dennis Marinus|title=Mass Mortality of Adult Male Subantarctic Fur Seals: Are Alien Mice the Culprits?|journal=PLOS ONE|date=19 November 2008|volume=3|issue=11|pages=e3757|doi=10.1371/journal.pone.0003757|pmid=19018284|pmc=2582944|bibcode=2008PLoSO...3.3757D |doi-access=free}}

In 2003, a rain-on-snow event encased the ground in ice, resulting in the starvation of 20,000 muskoxen on Banks Island in the Canadian Arctic.{{Cite journal|last1=Putkonen|first1=Jaakko|last2=Grenfell|first2=Thomas C.|last3=Rennert|first3=Kevin|last4=Bitz|first4=Cecilia|last5=Jacobson|first5=Paul|last6=Russell|first6=Don|title=Rain on Snow: Little Understood Killer in the North|journal=Eos|date=30 June 2009|volume=90|issue=26|pages=221–222|doi=10.1029/2009EO260002|bibcode=2009EOSTr..90..221P |doi-access=free}}{{Cite journal|last1=Berger|first1=J.|last2=Hartway|first2=C.|last3=Gruzdev|first3=A.|last4=Johnson|first4=M.|title=Climate Degradation and Extreme Icing Events Constrain Life in Cold-Adapted Mammals|journal=Scientific Reports|date=18 January 2018|volume=8|issue=1|pages=1156|doi=10.1038/s41598-018-19416-9|pmid=29348632|pmc=5773676|bibcode=2018NatSR...8.1156B }}

Shortly before midnight on New Year's Eve 2010, between 3,000 and 5,000 red-winged blackbirds fell from the sky in Beebe, Arkansas. Most died upon hitting the ground, but some were living but dazed. Laboratory tests were performed and the Arkansas Livestock and Poultry Commission, the National Wildlife Health Center in Madison, Wisconsin, and the University of Georgia's wildlife disease study group procured specimens of the dead birds. In addition to the blackbirds, a few grackles and starlings also fell from the sky in the same incident. A test report from the state poultry lab concluded that the birds had died from blunt trauma, with an unlicensed fireworks discharge being the likely cause.{{Cite news|url=https://www.usatoday.com/news/nation/2011-01-05-arkansas-dead-birds-fireworks_N.htm|title=Fireworks likely cause of massive Ark. bird kill|last=Weise|first=Elizabeth|date=5 January 2011|work=USA Today|access-date=19 January 2011}}{{Cite web|url=http://www.katv.com/Global/story.asp?S=13784010|title=911 Tapes Released from Beebe Bird Scare|date=7 January 2011|publisher=KATV|access-date=19 January 2011}}

The months-long Deepwater Horizon oil spill that began in April 2010 in the coastal waters of the Gulf of Mexico resulted in about 600,000 to 800,000 bird mortalities.{{Cite journal| doi = 10.3354/meps10839| volume = 513| pages = 239–252| last1 = Haney| first1 = J.| last2 = Geiger| first2 = Hal| last3 = Short| first3 = Jeffrey| title = Bird mortality from the Deepwater Horizon oil spill. II. Carcass sampling and exposure probability in the coastal Gulf of Mexico| journal = Marine Ecology Progress Series| date = 22 October 2014 | bibcode = 2014MEPS..513..239H|access-date=26 December 2020 |url=https://www.researchgate.net/publication/278196709| doi-access = free}} Dolphins and other species of marine life continued to die in record numbers into 2013.{{Cite web |url=http://news.discovery.com/animals/whales-dolphins/record-dolphin-sea-turtle-deaths-since-gulf-spill-130402.htm |archive-url=https://web.archive.org/web/20160130231923/http://news.discovery.com/animals/whales-dolphins/record-dolphin-sea-turtle-deaths-since-gulf-spill-130402.htm |date=2 April 2013 |archive-date=30 January 2016 |title=Record Dolphin, Sea Turtle Deaths Since Gulf Spill |first=Jen |last=Viegas |access-date=26 December 2020}}

The Beebe, Arkansas bird deaths were repeated again on New Year's Eve of the following year, 2011, with the reported number of dead birds being 5,000.{{Cite news|url=http://www.boston.com/news/nation/articles/2011/12/31/dead_blackbirds_fall_again_in_arkansas_town/|title=Dead blackbirds fall again in Arkansas town|date=31 December 2011|work=The Boston Globe|access-date=1 January 2012|agency=Associated Press}}

On 3 January 2011, more than five hundred starlings, red-winged blackbirds, and sparrows fell dead in Pointe Coupee Parish, Louisiana.{{Cite web|url=http://www.2theadvocate.com/news/112843019.html|title=Mass La. bird deaths puzzle investigators|last=Addo|first=Koran|date=4 January 2011|publisher=2theadvocate|url-status=live|archive-url=https://web.archive.org/web/20110115004923/http://www.2theadvocate.com/news/112843019.html|archive-date=15 January 2011 |access-date=23 January 2011}}

On 5 January, "hundreds" of dead turtle doves were found at Faenza, Italy.{{Cite news|url=http://www.huffingtonpost.com/2011/01/06/birds-dying-in-italy-thou_n_805541.html|title=Birds Dying in Italy: Thousands of Turtle Doves Fall Dead From Sky|date=6 January 2011|work=HuffPost|access-date=16 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110109123829/http://www.huffingtonpost.com/2011/01/06/birds-dying-in-italy-thou_n_805541.html|archive-date=9 January 2011 }} According to Italian news agencies, a huge number of the birds were found to have blue stains on their beaks that may have been caused by paint or hypoxia.{{Cite news|url=http://www.huffingtonpost.com/2011/01/10/dead-birds-fall-from-sky-_1_n_806724.html|title=Dead Birds Fall From Sky in Italy: Mass Animal Death Mystery Solved?|work=HuffPost|access-date=16 January 2011|date=10 January 2011}}

Over the weekend of 8–9 January, "over a hundred" dead birds were found clustered together on a California highway, while "thousands of dead gizzard shad" (a species of fish) turned up in the harbors of Chicago.{{Cite news|url=http://www.huffingtonpost.com/2011/01/11/birds-fall-from-sky-california_n_807330.html|title=Birds Fall From Sky in California, Thousands of Dead Fish Found in Chicago|last=Donovan|first=Travis Walter|date=11 January 2011|access-date=23 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110112133649/http://www.huffingtonpost.com/2011/01/11/birds-fall-from-sky-california_n_807330.html|archive-date=12 January 2011 |work=HuffPost}}{{Cite web|url=http://www.nbcchicago.com/news/local-beat/Thousands-of-dead-fish-along-lakefront-113267599.html|title=Thousands of Dead Fish Along Lakefront|date=12 January 2011|publisher=NBC Chicago|url-status=live|archive-url=https://web.archive.org/web/20110113032309/http://www.nbcchicago.com/news/local-beat/Thousands-of-dead-fish-along-lakefront-113267599.html|archive-date=13 January 2011 |access-date=23 January 2011}}

Between 28 December 2010 and 3 January 2011, 100 tons of dead fish washed ashore on the Brazilian coast.{{Cite web|url=http://www.parana-online.com.br/editoria/cidades/news/502434/?noticia=MORTANDADE+MISTERIOSA+DE+PEIXES+NO+LITORAL|title=Mortandade misteriosa de peixes no litoral|last=Coleto|first=Leonardo|date=4 January 2011|publisher=Parana Online|language=pt|access-date=23 January 2011}}

On 3 January, an estimated two million dead fish were found floating in the Chesapeake Bay in Maryland.{{Cite news|url=https://www.cbsnews.com/news/two-million-dead-fish-appear-in-chesapeake-bay/|title=Two Million Dead Fish Appear in Chesapeake Bay|publisher=CBS|date=5 January 2011}}

On 7 March, millions of small fish, including anchovies, sardines, and mackerel, were found dead in the area of King Harbor at Redondo Beach, California. An investigation by the authorities within the area concluded that the sardines had become trapped within the harbor and depleted the ambient oxygen, which resulted in the deaths. The authorities stated that the event was "unusual, but not unexplainable".{{Cite web|url=http://abcworldnews.tumblr.com/post/3725573415/millions-of-dead-fish-at-king-harbor-in-redondo|title=Millions of dead fish at King Harbor in Redondo Beach, CA|url-status=dead|archive-url=https://web.archive.org/web/20110312055703/http://abcworldnews.tumblr.com/post/3725573415/millions-of-dead-fish-at-king-harbor-in-redondo|archive-date=12 March 2011|access-date=9 March 2011}}

On 14 January, approximately two hundred cows were found dead in a field in Stockton, Wisconsin. The owner of the cattle has told deputies that he suspected the animals died of infectious bovine rhinotracheitis (IBR), or bovine virus diarrhea (BVD). Authorities in Wisconsin sent samples from the carcasses to labs in Madison in order to determine cause of death.{{Cite magazine|url=https://newsfeed.time.com/2011/01/18/does-the-death-of-200-cows-in-wisconsin-confirm-biblical-prophecy/|title=Does the Death of 200 Cows in Wisconsin Confirm Biblical Prophecy?|author=Adams, William Lee|date=18 January 2011|magazine=Time|access-date=19 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110223132938/http://newsfeed.time.com/2011/01/18/does-the-death-of-200-cows-in-wisconsin-confirm-biblical-prophecy/|archive-date=23 February 2011 }}

On 5 August, around 100 tonnes of dead fish, primarily mullets, were found floating in Karachi Port Trust waters, including Karachi harbour, Manora channel, and Chinna Creek.{{cite news |last1=Ilyas |first1=Faiza |title=Mass fish deaths blamed on toxic waste |url=https://www.dawn.com/news/1034275 |access-date=7 February 2025 |work=Dawn.com |publisher=Dawn |date=6 August 2013 |language=en}}

In 2015, some 200,000 saiga antelope died within a period of one week in a {{Cvt|20|km2}} area of the Betpak-Dala desert region of Kazakhstan. They had gathered in large groups for their annual calving. It was determined that warm and humid temperatures had caused Pasteurella multocida, a strain of bacteria that normally lives harmlessly in their tonsils, to cross into their bloodstream and cause hemorrhagic septicemia. This event wiped out 60% of the population of this critically endangered species.

Mass mortality events are not uncommon for saiga. In 1981, 70,000 died; in 1988 there were 200,000 deaths; and more recently, in 2010, 12,000 died.{{Cite web|title=Catastrophic Collapse of Saiga Antelopes in Central Asia|url=https://www.unenvironment.org/news-and-stories/press-release/catastrophic-collapse-saiga-antelopes-central-asia|website=UN Environment|date=5 October 2017 |access-date=25 February 2018|language=en}}

Starting in the summer of 2015 and continuing into the spring of 2016, about 62,000 dead or dying birds were found on Pacific Ocean beaches from California to Alaska. Some researchers believe that as many as one million common murres may have died in the massive die-off.{{Cite news| last = Mogensen| first = Jackie Flynn| title = A new study about the death of 1 million seabirds should scare the crap out of you| work = Mother Jones| access-date = 26 December 2020| date = 15 January 2020| url = https://www.motherjones.com/environment/2020/01/a-new-study-death-of-1-million-common-murres/}}

In May 2016, the Los Angeles Times reported that millions of fish had washed ashore along the coast of north-central Vietnam, stretching over {{convert|201|km}} of beaches.{{Cite news| last = Harris| first = Scott Duke| title = Millions of dead fish on Vietnam's shores raise industrial pollution fears| work = Los Angeles Times| access-date = 26 December 2020| date = 4 May 2016| url = https://www.latimes.com/world/asia/la-fg-vietnam-fish-20160504-story.html}} This included the shoreline in the Phu Loc district, in Thua Thien Hue province. Possible causes include industrial pollution, as government researchers had found that "toxic elements" had caused the "unprecedented" fish mortalities. Concerns were raised about a "massive Taiwanese-owned steel plant" that was allegedly "pumping untreated wastewater" into the ocean.

In the Inyo National Forest in California, there are several records of large numbers of migrating mule deer falling to their deaths by slipping on ice while crossing mountain passes. This has occurred when heavy snowfalls have persisted until fall, and have been turned to ice by frequent thawing and refreezing.{{Cite news|last1=Rea|first1=Sarah|title=A Slippery Slope|url=http://thesheetnews.com/2017/11/22/a-slippery-slope/|access-date=25 February 2018|work=The Sheet|date=22 November 2017}}

In 2019, an extreme heatwave with temperatures exceeding {{Cvt|42|C}} in central Australia lead to the death of approximately 40 brumbies.{{Cite news|url=https://www.theguardian.com/australia-news/2019/jan/23/shocking-pictures-show-dead-horses-at-dried-up-waterhole-in-central-australia|title=Shocking pictures show dead horses at dried-up waterhole in central Australia|last=Cox|first=Lisa|date=23 January 2019|work=The Guardian|access-date=26 July 2019|language=en-GB|issn=0261-3077}}

{{Main|Australian flying fox die-offs}}

In 2014 and 2018, heatwaves in Australia killed significant portions of local bat populations.

In August 2020, observers reported that hundreds of dead migratory birds heading south for the winter had been found at the White Sands Missile Range in New Mexico.{{Cite news| issn = 0261-3077| last = Weston| first = Phoebe| title = Birds 'falling out of the sky' in mass die-off in south-western US| work = The Guardian| access-date = 26 December 2020| date = 16 September 2020| url = https://www.theguardian.com/environment/2020/sep/16/birds-falling-out-of-the-sky-in-mass-die-off-in-south-western-us-aoe}} By September, the number had increased to tens of thousands, and the die-off had spread across at least New Mexico, Colorado, Texas, Arizona, and farther north into Nebraska.{{Cite news| last = Fox| first = Alex| title = Thousands of Migrating Birds Drop Dead Across Southwestern U.S.| work = Smithsonian Magazine| access-date = 26 December 2020| date = 17 September 2020| url = https://www.smithsonianmag.com/smart-news/thousands-migrating-birds-drop-dead-across-southwestern-us-180975828/}} The birds were migrating species, including "owls, warblers, hummingbirds, loons, flycatchers, and woodpeckers". They seemed to be emaciated, as if they had just kept on flying until they dropped. Possible causes of the deaths include climate crisis and wildfires, according to The Guardian.

{{Main articles|2022 Oder environmental disaster}}

In 2022, a mass die-off of fish, beaver and other wildlife occurred in the Oder river, between Poland and Germany.{{Cite news |last=Strzelecki |first=Marek |date=2022-08-12 |title=Dead fish in River Oder on Polish-German border spur contamination probe |language=en |work=Reuters |url=https://www.reuters.com/world/europe/dead-fish-river-oder-polishgerman-border-spur-contamination-probe-2022-08-11/ |access-date=2022-08-14}}

In March 2023, millions of fish were reported dead along the Darling River at Menindee, following a heatwave.{{cite news |last1=Radford |first1=Antoinette |title=Menindee: Millions of dead fish wash up near Australian town |url=https://www.bbc.com/news/world-australia-64992726 |access-date=20 March 2023 |work=BBC |date=18 March 2023}} Initially, police attributed the cause to (naturally occurring) hypoxic blackwater.{{cite news |last1=Housden |first1=Tom |title=Menindee: Australia begins mass fish death clean-up |url=https://www.bbc.com/news/world-australia-65010344 |access-date=20 March 2023 |work=BBC |date=20 March 2023}} Subsequently it was announced that the New South Wales government will treat the deaths as a "pollution incident", thus giving the Environmental Protection Authority (EPA) greater investigative powers.{{cite news |url=https://www.theguardian.com/australia-news/2023/apr/19/nsw-to-investigate-menindee-mass-fish-kill-as-pollution-incident |title=NSW to investigate Menindee mass fish kill as 'pollution incident' |work=The Guardian|author-first1=Fleur|author-last1=Connick|date=19 April 2023 |access-date=21 April 2023}}

{{main|2023 Texas dairy farm explosion}}

In April 2023, an explosion and subsequent fire at South Fork Dairy, near Dimmitt, Texas resulted in the deaths of an estimated 18,000 dairy cattle.{{Cite news |url=https://www.bbc.com/news/world-us-canada-65258108 |title=18,000 cows killed in Texas dairy farm explosion |author=Bernd Debusmann Jr |work=BBC News |date=2023-04-13 |access-date=2023-04-13}}

According to most scientists, massive die-offs of animals are not necessarily unusual in nature and may happen for any of a wide variety of reasons, both preventable and unpreventable. Natural causes often include severe weather, volcanic eruptions, disease outbreaks, and accidental poisonings,{{Cite news|url=http://news.discovery.com/animals/bird-animal-die-offs-110106.html|title=Birds Falling From the Sky Not Unusual|author=Sohn, Emily|date=6 January 2011|work=Discovery News|access-date=19 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110126213444/http://news.discovery.com/animals/bird-animal-die-offs-110106.html|archive-date=26 January 2011 }} while human-caused die-offs are typically due to pollution (especially major oil and chemical spills) and climate change adding to the stresses on wildlife.{{Cite news|url=http://www.newsdaily.com/stories/tre70534t-us-deaths/|title=SCIENCE NEWS Mass bird deaths rare, not apocalyptic: experts|author=Doyle, Alister|date=6 January 2011|work=NewsDaily.Com|access-date=19 January 2011|agency=Reuters}} The U.S. Geological Survey's website listed about 90 mass deaths of birds and other wildlife from June through 12 December 2010;{{Cite news|url=http://www.huffingtonpost.com/huff-wires/20110104/us-odd-dead-birds/|title=La. has mass bird kill just days after Ark.|author=McConnaughey, Janet|date=4 January 2011|work=HuffPost|access-date=19 January 2011}} Louisiana's State Wildlife Veterinarian Jim LaCour stated that there had been 16 similar mass blackbird deaths in the previous 30 years.{{Cite news|url=http://theweek.com/article/index/210739/the-arkansas-blackbirds-and-8-other-mysterious-mass-animal-deaths|title=Fact Sheet: The Arkansas blackbirds and 8 other mysterious mass animal deaths|date=5 January 2011|work=The Week|access-date=19 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110119035620/http://theweek.com/article/index/210739/the-arkansas-blackbirds-and-8-other-mysterious-mass-animal-deaths|archive-date=19 January 2011 }} Sudden or short-term die-offs must also be distinguished from much longer-term extinction events, which have occurred naturally for countless species throughout the Earth's history and for many extant species are often demonstrated to be ongoing, if gradually, in the modern era.

On the other hand, some mass die-offs appear to be unique because there are no previous records of similar occurrences, or because the likely cause of death can be pinpointed to a novel man-made event that has never previously existed; human technologies of a type or scale unknown at any prior point in history are frequently implicated in catastrophic mortality events. These types of mass die-offs are, then, unusual by definition. According to Italy's WWF president Giorgio Tramonti, mass dove deaths like the ones that occurred in Italy had never happened before 2010.{{Cite news|url=https://www.thestar.com/news/world/article/917889--aflockalypse-now-hundreds-of-turtle-doves-die-in-italy?bn=1|title='Aflockalypse' now: Hundreds of turtle doves die in Italy|author=Taylor, Lesley Ciarula|date=7 January 2011|work=Toronto Star|access-date=19 January 2011}} The event in Arkansas was attributed primarily to an unexpected temperature change causing atmospheric turbulence (visible on NEXRAD Doppler weather radar images) above the birds' roosting areas, which likely disoriented them.{{Cite news|url=http://www.news-herald.com/articles/2011/06/03/news/nh4082143.txt|title=Mark Johnson helps solve bird death mystery|last=Jackson|first=Rachel|date=3 June 2011|work=The News-Herald|access-date=3 June 2011}}

Some Christians {{which|date=August 2022}} asserted that the cluster of cow deaths in 2011 was a sign of the Apocalypse.{{Cite magazine|url=https://newsfeed.time.com/2011/01/18/does-the-death-of-200-cows-in-wisconsin-confirm-biblical-prophecy/|title=Does the Death of 200 Cows in Wisconsin Confirm Biblical Prophecy?|author=Adams, William Lee|date=18 January 2011|magazine=Time|access-date=19 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110223132938/http://newsfeed.time.com/2011/01/18/does-the-death-of-200-cows-in-wisconsin-confirm-biblical-prophecy/|archive-date=23 February 2011 }} They reference a passage in the Book of Hosea in the Hebrew Bible which reads: "By swearing, and lying, and killing, and stealing, and committing adultery, they break out, and blood toucheth blood," and the prophecy continues "Therefore shall the land mourn, and every one that dwelleth therein shall languish, with the beasts of the field, and with the fowls of heaven; yea, the fishes of the sea also shall be taken away."

The term aflockalypse was adopted by some media commentators in reference to the 2010–2011 bird deaths.{{Cite magazine|url=https://science.time.com/2011/01/05/why-the-aflockalypse-is-business-as-usual%E2%80%94and-why-thats-not-good/|title=Why the Aflockalypse Is Business As Usual For Biodiversity—And Why That's Not Good|last=Walsh|first=Brian|date=5 January 2011|magazine=Time|access-date=23 January 2011|url-status=live|archive-url=https://web.archive.org/web/20110110095448/http://ecocentric.blogs.time.com/2011/01/05/why-the-aflockalypse-is-business-as-usual%E2%80%94and-why-thats-not-good/|archive-date=10 January 2011}}{{Cite news|url=http://voices.washingtonpost.com/blog-post/2011/01/dead_birds_dead_fish_turn_up_a.html|archive-url=https://archive.today/20120717101332/http://voices.washingtonpost.com/blog-post/2011/01/dead_birds_dead_fish_turn_up_a.html|url-status=dead|archive-date=17 July 2012|title=Dead birds, dead fish, dead crabs turn up all over the world: Signs of the Aflockalypse?|first=Melissa|last=Bell|newspaper=The Washington Post|date=5 January 2011|access-date=23 January 2011}} Aflockalypse is a portmanteau of the words "flock" and "apocalypse".

• Fish kill
• Harmful algal bloom

{{Reflist}}{{Global warming}}

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Category:Natural disasters

Category:Biological events

Category:Animal death