Download BrownTreeSnake

Brown Tree
Snake
Boiga irregularis
Sanngeeta Macko
Giovana Olivera
Introduction
• Northern Australia’s ‘‘Doll’s
Eye’’
• Family
- Colubridae
• Color pattern:
- banded or unmarked
- brown, blue, or reddish
brown body color
• Nocturnal
- elliptical pupils
• Blunt short snout
• Teeth
- upper rearmost are
enlarged and groove
to facilitate penetration
of venom into prey
• Large eyes
• Very slender body shape
• Arboreal
USGS
Geographic Distribution
• Australia – Native
• Papua New Guinea – Native
• Solomon Islands – Native
• Guam – Introduced
USGS
Guam
Invasive
• Introduced from Australasia to
Guam
• Brown Tree Snakes arrived
on Guam around 1949
• World War II – on cargo ship
from New Guinea
• Presently distributed
throughout the island
with population densities
approaching 100 snakes
per Ha in some areas
• Continued survival:
supported by
abundant introduced
prey species
- skinks
- geckos
- rodents
- a variety of
introduced birds
• Guam now has the only
extra-limit
population of brown
tree snakes
Economic Impact
Guam
• Damage to electrical power
infrastructure
- Guam experiences a
snake-caused power
outage about every
other day on average
- Costs include direct
damage to the electrical
infrastructure
- Emergency restoration
costs
- Disruption of normal
urban functions
• Higher costs of shipping
from Guam
• Threats to the tourism
industry
USGS
Impact on Wildlife
Guam
• Caused extinction or extirpation of 13 bird species
Micronesian kingfisher
USGS
Guam flycatcher
USGS
Impact on Wildlife
Guam
• In 1982, there were 1000 fruit bats in Guam. Since then
this number has been quickly declining.
• The Tree Brown Snake feed on juvenile fruit bats that
drop off from tree tops.
USGS
Impact on Wildlife
Guam
• Extinction and Loss of Species : Lizards
Snake-eyed skink
USGS
Azure-tailed skink
USGS
Impact on Humans
Guam
•Victims of envenomations
- Sleeping infants
• Brown Tree Snakes consume many pet
animals on Guam especially puppies
as well as caged birds.
Department of land and
natural resources
State of Hawaii
ALIEN SPECIES
• The primary loss of domestic animals
-poultry
USGS
What Is Being Done To Control Damage by the
Brown Tree Snake?
• Wildlife Services (WS)
Part of the U.S. Department of
Agriculture’s (USDA) and Plant Health
Inspection Service (APHIS)
Pacific Basin Information Node (PBIN)
• Stopped from reaching other destinations
by…
1. Snake trapping
2. Night time spotlight searches
3. Cargo Fumigants
- Reduces the number of snakes in area
where cargo is packed or stored.
- Trained Jack Russell terriers
USDA
Benefits
Guam
•Introduced small mammals
- rats
• Less numerous than they were
before the arrival of the
Brown Tree Snake
www.answers.com
Biology and Impacts of Pacific Island Invasive Species:
Boiga irregularis, the Brown Tree Snake
• The Brown Tree Snake, Boiga irregularis was accidentally
transported to the island of Guam shortly after World War
II.
• This secretive nocturnal arboreal snake occurs in all habitats on
Guam, from grasslands to forests.
• The Brown Tree Snake caused the extirpation of 13 of Guam’s
22 native breeding birds (including 10 of 12 forest birds)
and contributed to the extirpation of several species of
native bats and lizards.
• Effect on Humans: domestic poultry, pets and electrical power.
• U.S. government annually spends several million dollars
inspecting cargo outbound from Guam to exclude Brown
Tree Snakes.
Amazing Arboreal Abilities
– Danger to bats and birds
Reproductive Biology of the Brown Tree Snake,
Boiga irregularis, during colonization of Guam and
comparison with that in their native range
• This study compared the reproductive biology of B. irregularis caught on Guam
during the 1980s with results from published studies of native-range
populations.
• A large # of male brown tree snakes on Guam appear physically capable of
inseminating females at all times of year.
• The snakes in Guam showed no evidence of reproductive seasonality. This is in
contrast to their Australian counterpart.
• Study found that sperm storage, though essential in parts of the native range, is
unnecessary for successful reproduction on Guam.
• Data from this study can provide a baseline for future comparisons and insight
into the colonization process by supplying a snapshot of the reproductive
characteristics of a recently established brown tree snake population.
Captured Brown Tree Snake
An Ecological Risk Assessment of Nonnative Boas and
Pythons as Potentially Invasive Species in the United States
• Within 50 years of its introduction to the formerly snake-free
island of Guam, B. irregularis had played a role in the loss
of 10 of 13 native bird species, 6 of 12 native lizard
species, and 2 of 3 bat species.
• This study used the information on the Brown Tree Snake to
model the risks associated with boas and pythons as
potential invasive species in the continental United States.
• Recommendations:
1. Increase the attractiveness of native snakes to potential
purchasers of pet snakes.
2. Imported snakes should be subject to increased
quarantine before sale in the domestic retail market.
3. Educational efforts aimed at reducing intentional releases of
non-native snakes should be increased.
An Ecological Risk Assessment of Nonnative Boas and
Pythons as Potentially Invasive Species in the United States
• These are the
numbers for
snakes legally
imported into the
United States!
Effectiveness of methyl bromide as a
cargo fumigant for Brown Tree Snakes
• The present study was designed to test whether the
fumigant, methyl bromide, would kill brown tree
snakes.
• Two-hour exposures to methyl bromide at 24 and 12gm3
appear to be effective in killing brown tree snakes
within reasonable time-frames for shippers under
Guam field conditions.
• The application rate of 24 gMBm3 for 2 h was the
treatment schedule of choice because it resulted in
100% mortality in a relatively short time.
• This study demonstrated that methyl bromide, at or
below many currently registered application rates,
consistently kills brown tree snakes in cargo
containers.
Fumigation is used as a way
of control
Effectiveness of methyl bromide as a
cargo fumigant for Brown Tree Snakes
• Dosage, exposure time, concentration time product,
and mortality of brown tree snakes fumigated
with methyl bromide in simulated cargo
containers.
Toward a comprehensive information system to assist
invasive species management in Hawaii and Pacific Islands
• There is a great need for coordinated regional and global electronic databases to
assist prevention, early detection, rapid response, and control of biological
invasions.
• The Pacific Basin Information Node (PBIN), of the National Biological Information
Infrastructure is the answer to this need and has been active since 2001.
• Initial emphasis on Hawaii, but now turned to other Pacific islands and countries.
• The PBIN’s projects are being developed in cooperation with the Brown Tree
Snake control efforts.
• The hope is that PBIN will play an important role in information gathering
and sharing for vastly improved collaboration among biodiversity
conservation, agricultural, and public health interests.
Spread of the the brown tree snake, would be devastating to the Pacific
Islands.
Fun Facts
• The Brown Tree Snake is longer (up to 3 m total length), skinnier,
more nocturnal, and more arboreal than an average snake.
• A favorite local name used in northern Australia - ‘‘Doll’s Eye”
Work Cited
Fornwall, Mark, and Lloyd Loope. "Toward a Comprehensive Information
System to Assist Invasive Species Management in Hawaii and Pacific
Islands." Weed Science 52 (2004): 854-856.
Reed, Robert N. "An Ecological Risk Assessment of Nonnative Boas and
Pythons as Potentially Invasive Species in the United States." Risk
Analysis 25 (2005): 753-756.
Rodda, Gordon H., and Julie A. Savidge. "Biology and Impacts of Pacific Island
Invasive Species. 2. Boiga Irregularis, the Brown Tree Snake (Reptilia:
Colubridae)." Pacific Science 61 (2007): 307-324.
Savariea, Peter J., W. Scott Wood, Gordon H. Rodda, Richard L. Bruggers, and
Richard M. Engema. "Effectiveness of Methyl Bromide as a Cargo
Fumigant for Brown Tree Snakes." International Biodeterioration and
Biodegradation 56 (2005): 40-44.
Savidge, Julie A., and Fiona J. Qualls. "Reproductive Biology of the Brown Tree
Snake, Boiga Irregularis (Reptilia: Colubridae), During Colonization of
Guam and Comparison with That in Their Native Range." Pacific
Science 61 (2007): 191-199.
Work Cited
Pictures
• http://www.aphis.usda.gov/lpa/pubs/btsbro.pdf
• http://www.state.hi.us/dlnr/Snake.html
• http://www.fort.usgs.gov/Resources/Education/BTS/
• http://www.terrierman.com/guamdog.bmp
• http://www.answers.com/topic/snake
Thank You