4: Extinction

Extinction is forever:

Tasmanian Tiger

Quagga

Tasmanian Tiger:

the last Tasmanian tiger died in Hobart Zoo in Tasmania, Australia on September 7, 1936

When did the last Tasmanian tiger die?

September 7, 1936

Quagga:

targeted by hunters for their unique hide

The last Quagga went extinct in Africa, probably killed in the late 1870s

The species went extinct on August 12, 1883 when the last one died in a zoo in Amsterdam

What were quagga targeted by hunters for?

their unique hide

When did the last Quagga go extinct in Africa?

probably killed in the late 1870s

When did the species quagga go extinct?

August 12, 1883

Extinctions of Islands - some general patterns of island endemics

Limited habitat

Overall small population size

Evolved in isolation

How does Overall small population size affect island endemics?

cannot be easily ‘rescued’ or recolonized by immigration

How does evolving in isolation affect island endemics?

species that often evolve in relative isolation, with limited competitors and predators (parasites and disease), evolve few defenses

How does species evolving in relative isolation, with limited competitors and predators (parasites and disease) affect their survival?

they evolve few defenses

Species-Area Curves

The smaller the island (area), the fewer species (populations) it can support

The smaller the island (area):

the fewer species (populations) it can support

Species on a smaller island have a ________ chance of going extinct

higher

Example of Species-Area Curves: Hawaiian Honeycreepers

Species Radiation

29 species went extinct prehistorically

8 extinct since 1778

Of the 20 remaining species, 14 are federally listed

What is Species Radiation?

After the settlement, the species/descendants of the original species take advantage of the numerous resources available and begin to diverge

One ancestral species of finch gave rise to as many as:

57 different species (known from historical records and fossils)

29 species of finch went extinct prehistorically following what?

Polynesian settlement

What did Polynesian settlement cause

extinction of 29 species of finch

8 species of finch went extinct since 1778 following what?

the historical European settlement

Of the 20 remaining species, how many are federally listed as endangered in modern times?

14

Prehistoric Extinctions on Polynesian Islands

Created a massive society on the islands

Hawaiian Islands were inhabited by Polynesians around 400 AD

At the time Europeans arrived in the late 1700s, the islands were inhabited by 200k people

Hawaiian Islands were inhabited by who?

Polynesians around 400 AD

At the time Europeans arrived in the late 1700s, the islands were inhabited by:

200k people

Causes for prehistoric extinctions on Polynesian islands:

Intense agriculture (most of the islands at lower elevations)

Forest cutting and burning: increases nutrients

Hunting (for finch feathers)

Introduction of pigs, rats, exotic insects, and plants

Not just honeycreepers on the Hawaii Islands

From fossil records, more than half of native bird species present when Polynesians colonized went extinct before Europeans arrived

By European arrival, human-caused extinctions had already decimated native animals on the Hawaiian islands (and many others)

By the time Europeans arrived, the most ‘extinction-prone’ species were already gone

From fossil records, what happened to more than half of native bird species present when Polynesians colonized?

went extinct before Europeans arrived

By European arrival, what had human-caused extinctions done?

already decimated native animals on the Hawaiian islands (and many others)

By the time Europeans arrived, what happened to the most ‘extinction-prone’ species?

they were already gone

Hawaiian Goose

1940s-1950s, wild population had fallen to ~ 30-50 birds (almost extinct)

Issues: introduced mongoose, cats, dogs, pigs, rats (predators)

Captive-breeding, reintroductions, predator controls began in the late 1940s

Listed as Endangered in 1967 under previous legislation

Carried over to ESA 1973

Currently ~ 3800 adults (not that recent)

Downlisted to Threatened in 2019

1940s-1950s, wild Hawaiian Goose population had fallen to?

~30-50 birds (almost extinct)

What Issues did Hawaiian Goose face?

introduced mongoose, cats, dogs, pigs, rats (predators)

What efforts began in the late 1940s to restore Hawaiian Goose?

captive-breeding, reintroductions, predator controls

When was the Hawaiian Goose listed as Endangered?

1967 under previous legislation

When was Hawaiian Goose listing carried over to ESA?

1973

‘Currently’ how many Hawaiian Goose exist?

~ 3800 adults

When were Hawaiian Goose Downlisted to Threatened?

2019

What were the causes of the loss and decline of Hawaiian Native Birds?

Habitat loss and degradation

Predation by introduced mammals, and other exotic species

Competition...

Susceptibility...

What did Hawaiian Native Birds face competition from?

introduced bird species

What were Hawaiian Native Birds susceptible to?

introduced bird species (avian malaria, transmitted by introduced mosquito species)

Human-caused threats to various groups of species in the U.S

• Leading causes for species declines in the US

• Older data (~2004) but pattern is still relevant

• Climate now recognized as drier

What were the leading causes for species declines in the US?

habitat loss/degradation

exotic species

number one factor: humans

What are the two Extinction-Prone Species labels?

Species that require large territories

Species with very limited natural ranges

Species are often extinction prone as:

groups

Species that require large territories factors:

Habitat susceptible to loss, fragmentation, or degradation

Low rates of reproduction

Often limited population sizes

“K-selected” species

What is a “K-selected” species?

species that are at the carrying capacity of their environment, meaning that there is lots of competition and resources are being used up

Species that require large territories factors are often:

larger

Species with very limited natural ranges factors:

Habitat susceptible to loss, fragmentation, or degradation

Often limited population sizes

Island endemics

Species with very limited natural ranges are often limited in?

their natural distribution

What is an example of an avian species that require large territories?

Condors

Condors

huge birds that soar over huge expanses in search of food, as much as 150 miles a day, and are bald and wash themselves

Require large amounts of space

By 1982, there were only 22 California Condors

What are some Threats to California Condors?

Shooting

Powerlines, fences

Contamination: poisons, consumed lead shot

How many California Condors were left by 1982?

only 22

What are Condors?

huge birds that specialize in scavenging large dead animals and require large amounts of space

California Condor Recovery Program

Listed as endangered in 1967, carried over to ESA 1973

California Condor Recovery Program Results:

not really increasing numbers/slow increase

What is an example of a land species that require large territories?

Brown Bear

Brown Bear:

Grizzly Bears

700-780kg (1500-1700lb)

Aggressive

Greater Yellowstone Ecosystem in which bears are managed

Evolved to protect larger animals

Most of the biggest parks and reserves are?

not big enough to protect many of our iconic species

Habitat Fragmentation has two major effects that reduce species survival in an area

Reduction in total habitat area

Redistribution of remaining habitat into fragments or patches

Reduction in total habitat area primarily affects?

population size

Redistribution of remaining habitat into fragments or patches primarily affects?

survival and dispersal

As habitat is fragmented, the smaller the habitat patch:

the fewer individuals (species) can be supported by the patch

derived from the species-area curve

Smaller, more isolated patches did not maintain?

community integrity (species diversity)

Great Basin mountain tops revisited:

Isolated high elevation ranges in the Great Basin

Described as the loss of populations over time, following the last glacial period

Non-equilibrium metapopulation

Non-equilibrium metapopulation:

none of the animals are dispersing between patches, cannot make movement; group of isolated populations

Described as the loss of populations over time, following the last glacial period:

As temperatures warmed up, conditions changed, and species became more isolated