A mass mortality event (MME) is an incident that kills a vast number of individuals of a single species in a short period of time. [1] The event may put a species at risk of extinction or upset an ecosystem. [2] This is distinct from the mass die-off associated with short lived and synchronous emergent insect taxa which is a regular and non-catastrophic occurrence. [3]
Causes of MME's include disease and human-related activities such as pollution. Climatic extremes and other environmental influences such as oxygen stress in aquatic environments play a role, as does starvation. In many MME's there are multiple stressors. [2] An analysis of such events from 1940 to 2012 found that these events have become more common for birds, fish and marine invertebrates, but have declined for amphibians and reptiles and not changed for mammals. [4]
In March 1904, 1.5 million migrating birds died in Minnesota and Iowa during a strong snowstorm. [5] According to The Guardian, this was the largest avian mortality event on record in the region. [5] Records of MMEs have been kept since the 1880s. [5] 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". [5]
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. [6]
In 1988, the deaths of 20,000 harbour seals in the North Sea were found to be caused by phocine distemper virus. [7]
Ten years later, two strains of bacteria were implicated in the deaths of approximately 1,600 New Zealand sea lions. [7]
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. [7]
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. [8] [9]
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. [10] [11]
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. [12] Dolphins and other species of marine life continued to die in record numbers into 2013. [13]
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. [14]
On 3 January 2011, more than five hundred starlings, red-winged blackbirds, and sparrows fell dead in Pointe Coupee Parish, Louisiana. [15]
On 5 January, "hundreds" of dead turtle doves were found at Faenza, Italy. [16] 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. [17]
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. [18] [19]
Between 28 December 2010 and 3 January 2011, 100 tons of dead fish washed ashore on the Brazilian coast. [20]
On 3 January, an estimated two million dead fish were found floating in the Chesapeake Bay in Maryland. [21]
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". [22]
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. [23]
In 2015, some 200,000 saiga antelope died within a period of one week in a 20 km2 (7.7 sq mi) 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. [24] [2]
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. [25]
In May 2016, the Los Angeles Times reported that millions of fish had washed ashore along the coast of north-central Vietnam, stretching over 201 kilometres (125 mi) of beaches. [26] This included the shoreline in the Phu Loc district, in Thua Thien Hue province. [26] Possible causes include industrial pollution, as government researchers had found that "toxic elements" had caused the "unprecedented" fish mortalities. [26] Concerns were raised about a "massive Taiwanese-owned steel plant" that was allegedly "pumping untreated wastewater" into the ocean. [26]
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. [27]
In 2019, an extreme heatwave with temperatures exceeding 42 °C (108 °F) in central Australia lead to the death of approximately 40 brumbies. [28]
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. [5] 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. [5] [29] The birds were migrating species, including "owls, warblers, hummingbirds, loons, flycatchers, and woodpeckers". [29] They seemed to be emaciated, as if they had just kept on flying until they dropped. [29] Possible causes of the deaths include climate crisis and wildfires, according to The Guardian. [5]
In 2022, a mass die-off of fish, beaver and other wildlife occurred in the Oder river, between Poland and Germany. [30]
In March 2023, millions of fish were reported dead along the Darling River at Menindee, following a heatwave. [31] Initially, police attributed the cause to (naturally occurring) hypoxic blackwater. [32] 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. [33]
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. [34]
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, [35] 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. [36] The U.S. Geological Survey's website listed about 90 mass deaths of birds and other wildlife from June through 12 December 2010; [37] Louisiana's State Wildlife Veterinarian Jim LaCour stated that there had been 16 similar mass blackbird deaths in the previous 30 years. [38] 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. [39] 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. [40]
Some Christians [ which? ] asserted that the cluster of cow deaths in 2011 was a sign of the Apocalypse. [41] They reference a passage in the Book of Hosea [41] 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." [41]
The term aflockalypse was adopted by some media commentators in reference to the 2010–2011 bird deaths. [42] [39] [43] Aflockalypse is a portmanteau of the words "flock" and "apocalypse".
Manatees are large, fully aquatic, mostly herbivorous marine mammals sometimes known as sea cows. There are three accepted living species of Trichechidae, representing three of the four living species in the order Sirenia: the Amazonian manatee, the West Indian manatee, and the West African manatee. They measure up to 4.0 metres long, weigh as much as 590 kilograms (1,300 lb), and have paddle-like tails.
Beebe is a city in White County, Arkansas, United States. The population was 7,315 at the 2010 U.S. Census, making it the second most populous in the county. The city is home to Arkansas State University-Beebe. ASU-Beebe also has branch campuses in Heber Springs and Searcy and at Little Rock Air Force Base.
The Darling River is the third-longest river in Australia, measuring 1,472 kilometres (915 mi) from its source in northern New South Wales to its confluence with the Murray River at Wentworth. Including its longest contiguous tributaries it is 2,844 km (1,767 mi) long, making it the longest river system in Australia. The Darling River is the outback's most famous waterway.
A rain of animals is a rare meteorological phenomenon in which flightless animals fall from the sky. Such occurrences have been reported in many countries throughout history. One hypothesis is that tornadic waterspouts sometimes pick up creatures such as fish or frogs, and carry them for up to several miles. However, this aspect of the phenomenon has never been witnessed by scientists.
The saiga antelope, or saiga, is a species of antelope which during antiquity inhabited a vast area of the Eurasian steppe, spanning the foothills of the Carpathian Mountains in the northwest and Caucasus in the southwest into Mongolia in the northeast and Dzungaria in the southeast. During the Pleistocene, it ranged across the mammoth steppe from the British Isles to Beringia. Today, the dominant subspecies only occurs in Kalmykia and Astrakhan Oblast of Russia and in the Ural, Ustyurt and Betpak-Dala regions of Kazakhstan. A portion of the Ustyurt population migrates south to Uzbekistan and occasionally to Turkmenistan in winter. It is regionally extinct in Romania, Ukraine, Moldova, China and southwestern Mongolia. The Mongolian subspecies occurs only in western Mongolia.
Bird conservation is a field in the science of conservation biology related to threatened birds. Humans have had a profound effect on many bird species. Over one hundred species have gone extinct in historical times, although the most dramatic human-caused extinctions occurred in the Pacific Ocean as humans colonised the islands of Melanesia, Polynesia and Micronesia, during which an estimated 750–1,800 species of birds became extinct. According to Worldwatch Institute, many bird populations are currently declining worldwide, with 1,200 species facing extinction in the next century. The biggest cited reason surrounds habitat loss. Other threats include overhunting, accidental mortality due to structural collisions, long-line fishing bycatch, pollution, competition and predation by pet cats, oil spills and pesticide use and climate change. Governments, along with numerous conservation charities, work to protect birds in various ways, including legislation, preserving and restoring bird habitat, and establishing captive populations for reintroductions.
The term fish kill, known also as fish die-off, refers to a localized die-off of fish populations which may also be associated with more generalized mortality of aquatic life. The most common cause is reduced oxygen in the water, which in turn may be due to factors such as drought, algae bloom, overpopulation, or a sustained increase in water temperature. Infectious diseases and parasites can also lead to fish kill. Toxicity is a real but far less common cause of fish kill.
A water bird, alternatively waterbird or aquatic bird, is a bird that lives on or around water. In some definitions, the term water bird is especially applied to birds in freshwater ecosystems, although others make no distinction from seabirds that inhabit marine environments. Some water birds are more terrestrial while others are more aquatic, and their adaptations will vary depending on their environment. These adaptations include webbed feet, beaks, and legs adapted to feed in the water, and the ability to dive from the surface or the air to catch prey in water.
Wildlife observation is the practice of noting the occurrence or abundance of animal species at a specific location and time, either for research purposes or recreation. Common examples of this type of activity are bird watching and whale watching.
White-nose syndrome (WNS) is a fungal disease in North American bats which has resulted in the dramatic decrease of the bat population in the United States and Canada, reportedly killing millions as of 2018. The condition is named for a distinctive fungal growth around the muzzles and on the wings of hibernating bats. It was first identified from a February 2006 photo taken in a cave located in Schoharie County, New York. The syndrome has rapidly spread since then. In early 2018, it was identified in 33 U.S. states and seven Canadian provinces; plus the fungus, albeit sans syndrome, had been found in three additional states. Most cases are in the eastern half of both countries, but in March 2016, it was confirmed in a little brown bat in Washington state. In 2019, evidence of the fungus was detected in California for the first time, although no affected bats were found.
The New River, also Río Nuevo, is a river in northern Belize. As the longest river that is entirely confined to Belize, it drains primarily the eastern part of the Orange Walk District during its north-northeasterly course and empties into the Chetumal Bay. The river also forms the New River Lagoon, the largest body of fresh water in Belize, just east of the Maya temples of Lamanai. The New River is a habitat for numerous types of fish and birds, as well as Morelet's crocodiles.
A harmful algal bloom (HAB), or excessive algae growth, is an algal bloom that causes negative impacts to other organisms by production of natural algae-produced toxins, mechanical damage to other organisms, or by other means. HABs are sometimes defined as only those algal blooms that produce toxins, and sometimes as any algal bloom that can result in severely lower oxygen levels in natural waters, killing organisms in marine or fresh waters. Blooms can last from a few days to many months. After the bloom dies, the microbes that decompose the dead algae use up more of the oxygen, generating a "dead zone" which can cause fish die-offs. When these zones cover a large area for an extended period of time, neither fish nor plants are able to survive. Harmful algal blooms in marine environments are often called "red tides".
The North Cape oil spill took place on January 19, 1996, when the tank barge North Cape and the tug Scandia grounded on Moonstone Beach in South Kingstown, Rhode Island, after the tug caught fire in its engine room during a winter storm. An estimated 828,000 US gallons (3,130 m3) of home heating oil was spilled. Oil spread throughout a large area of Block Island Sound, including Trustom Pond National Wildlife Refuge, resulting in the closure of a 250-square-mile (650 km2) area of the sound for fishing.
Bird kill is a localized event resulting in the death of large numbers of birds at the same time.
Pansteatitis, or yellow fat disease, is a physiological condition in which the body fat becomes inflamed.
The Menindee Lakes is a system of 9 large, but relatively shallow lakes, located in south-west New South Wales on the Darling (Barka) River, about 200 km upstream of the Darling River's junction with the River Murray. The Darling River is fed by nine major tributary river systems flowing from south-east Queensland and north and central NSW. The town of Menindee is close to the lakes and Sunset Strip township is on the northern shore of Lake Menindee. The nearest city is Broken Hill.
Ecological light pollution is the effect of artificial light on individual organisms and on the structure of ecosystems as a whole.
Migrating birds face many perils as they travel between breeding and wintering grounds each year.
The National Wildlife Health Center (NWHC) is a science center of the United States Geological Survey. NWHC is located in Madison, Wisconsin, on a 24-acre plot of land that includes a main building and tight isolation building (TIB). The facility houses Bio-safety Level 3 (BSL-3) and Bio-safety Level 2 (BSL-2) laboratories on site.
The 2021 North-East England shellfish die-off was a series of occasions where a mass of shellfish were found on beaches on the Durham and Yorkshire Coasts in northern England, either dead, or in stages of dying.