Download Invasive Seabirds Lesson 2 Seabirds

INVASIVE SPECIES AND SEABIRDS
Lesson: 2
Invasive
Species
and
Biodiversity
©Ram Papish
Key Concepts
• Invasive species
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Characteristics
Alaska Islands and Juan Fernández Islands, Chile
• Biodiversity
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What is it and why is it important?
• Islands and seabirds
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How is island biodiversity unique?
Invasive species on islands with seabirds: A bigger threat
Lesson 2: Invasives and Biodiversity
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Invasive Species
• Introduced species: also called alien or exotic species
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Not originally from a place
Arrive through human activities
• Species arriving on their own via wind, flying,
walking, etc. are NOT considered introduced species
• Invasive species: an introduced species that
significantly impacts an ecosystem and poses a
threat to the environment, human health, or the
economy
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Invasive Species
• Key characteristics of a potentially invasive species
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Few natural controls on the population
Reproduce quickly
Can adapt to many different habitats
Able to migrate easily
Generalists, i.e. can eat a variety of foods and live in a
variety of habitats
Efficient defenses and/or are aggressive predators
Overcome natural barriers to dispersal
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Invasive Species − Alaska
• Introduced invasive plants, rats, fishes, snails, birds,
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frog, mussels, and other organisms threaten the
native ecosystem
Fragile island ecosystems are being threatened by
rats, cattle, reindeer, and foxes
Rats are particularly devastating to nesting seabirds
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Approximately 50 million seabirds nest on Alaska’s coast
87% of the seabirds in the United States nest in Alaska
80% of the world’s endangered Red-legged Kittiwake
population breeds on St. George Island in the Pribilofs
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Invasive Species − Alaska Islands
• Norway Rat (Rattus norvegicus)
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Stowaways on ocean-going vessels
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Invasive Species − Alaska Islands
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Invasive Species − Alaska Islands
• Arctic Fox (Alopex lagopus) and Red Fox (Vulpes vulpes)
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Both are native to mainland Alaska
Arctic fox is native to the Pribilof Islands
Neither is native to Aleutian Islands
 Introduced for the fur trade
©Robin West, USFWS
Red Fox (Vulpes vulpes)
©Wikicommons, USFWS
©Pam Goddard, Thalassa
Arctic Fox (Alopex lagopus) (Vulpes lagopus pribilofensis)
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Invasive Species − Alaska Islands
• Cattle & Reindeer
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Intentionally introduced for food
©Ann Harding
Reindeer, St. George Island, Alaska
Cattle, Chirikof Island, Alaska
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Invasive Species − Juan Fernández Islands
Chile
The Juan Fernández Islands are located 670 km (416 mi) off the coast of
Chile. They are composed of 3 main volcanic islands; Robinson Crusoe,
Alejandro Selkirk, and Santa Clara.
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Invasive Species − Juan Fernández Islands
• Introduced invasive plants, goats, rabbits, coatis, feral
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cats, mice, and rats threaten the native ecosystem.
Islands are home to two Critically Endangered singleisland endemic land birds
2/3 of all native plants are endemic to the islands
Nesting habitat for four threatened seabird populations
that breed only on Chilean Islands
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Two species are single-island endemics (entire world
population is on one island, Alejandro Selkirk)
Two species breed only on the three islands in Chile
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Invasive Species − Juan Fernández Islands
• European Rabbit (Oryctolagus cuniculus)
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Introduced on islands as a food source for marooned
sailors
:© Juan Fernández Islands Conservancy, 2002
At right: Pink-footed Shearwater eggs ejected from seabird burrows by European
Rabbit disturbance in the breeding colony.
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Invasive Species − Juan Fernández Islands
• Feral goats (Capra hircus)
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Introduced for food on long sea voyages during
European exploration and colonization in the 18th and
19th centuries
©Peter Hodum
©Peter Hodum
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Invasive Species−Juan Fernández Islands
• Coati (Nasua nasua)
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Two pregnant females were brought from Perú to
Robinson Crusoe Island in 1935 to eliminate the rats
By 1972 the population had grown to 4,000
©Vassil, Wikimedia Commons
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Invasive Species−Juan Fernández Islands
• Feral and domestic cats
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Introduced as pets
©Peter Hodum
©Peter Hodum
Pink-footed Shearwater
killed by feral cat.
©Peter Hodum
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Invasive Species−Juan Fernández Islands
• Norway Rat (Rattus norvegicus)
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Stowaways on ocean-going vessels
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Biodiversity
• Biodiversity: variety of life found on Earth
• Biodiversity can be applied to any size environment
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A specific region or space, e.g. a country, continent, town,
backyard
• How is biodiversity measured?
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Species richness: the number of species present
Genetic variation: differences in the physical features of
individuals within a species
Ecological communities: groups of species co-existing
Habitat: natural environment where groups of species live
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Biodiversity: Ecological Communities
• Species evolve together
• Every species has a role
• Interconnected roles
make up a food web
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Biodiversity on Islands
• Island biodiversity is different from other spaces
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Geographical size
Unique habitats
Distance from the mainland
Isolation because surrounded by water
• Endemic species
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Specially adapted to the
unique habitat features of a
location such as an island
Restricted to a certain area
and not found anywhere
else in the world
Lesson 2: Invasives and Biodiversity
Pink-footed Shearwater
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Biodiversity on Islands
• Island habitats are vulnerable to changes
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Most lack predators so species have lost defenses
Population sizes are often small
Genetic diversity may be low
Species are concentrated in small areas
• Significant threats to island biodiversity include:
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Habitat destruction – often by humans
Invasive species
St. Paul Island vehicle boneyard
prior to clean up.
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Island Habitats and Invasive Species
• Non-native species are a direct threat to island
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biodiversity.
A successful invasive species can decimate native
populations of animals, severely impacting the food
web and the balance of the ecosystem.
May drive native species to extinction or extirpation
via competition or predation.
Seabirds are at particular risk.
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Seabirds and Invasive Species
Seabirds are at particular risk from invasive species
• Burrow or nest on the ground, easy prey
• Evolved without land-based predators
• No effective defenses
Horned Puffin and chick
©Ann Harding
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Seabirds and Invasive Species
• Seabird populations are higher on predator free
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islands
Ecosystems productivity (e.g., guano, poop fertilizer)
is reduced when seabird populations decline
©I. Jones
Least Auklet eggs preyed on
by rats, Kiska Island, Alaska..
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Summary
• Invasive species: an introduced species that
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significantly modifies or disrupts an ecosystem and
poses a threat to the environment, human health, or
the economy.
Biodiversity: the variety of life on earth. This concept
can be applied to any size region such as islands,
continents, and backyards.
Invasive species are a threat to biodiversity.
Island seabird populations are particularly
vulnerable to invasive species.
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Resources & References
• Alaska Department of Fish and Game
www.adfg.alaska.gov/index.cfm?adfg=invasive.main
• U.S. Fish and Wildlife Service
www.fws.gov/invasives/
• Global Invasive Species Database
www.issg.org/database/welcome/
• Coastal Conservation
coastalconservation.ca/about-us/
• Island Conservation
www.islandconservation.org/
• Oikonos
oikonos.org/
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