Brown Tree Snake

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Brown Tree Snake
Boiga irregularis
Sanngeeta Macko Giovana Olivera
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Introduction

• Northern Australias Dolls Eye

• Family
• - Colubridae
• Nocturnal
• - elliptical pupils
• Arboreal

• Color pattern
• - banded or unmarked
• - brown, blue, or reddish brown body color
• Blunt short snout
• Large eyes
• Very slender body shape

• Teeth
• - upper rearmost are enlarged and groove
• to facilitate penetration of venom into
  prey

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USGS
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Geographic Distribution

• Australia Native
• Papua New Guinea Native
• Solomon Islands Native
• Guam Introduced

USGS
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GuamInvasive

• Introduced from Australasia to
• Guam
• Brown Tree Snakes arrived
• on Guam around 1949
• World War II on cargo ship
• from New Guinea

• 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

• Presently distributed throughout the island
  with population densities approaching 100
  snakes
• per Ha in some areas

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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
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Impact on Wildlife
Guam

• Caused extinction or extirpation of 13 bird
  species

Micronesian kingfisher
Guam flycatcher
USGS
USGS
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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
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Impact on Wildlife
Guam

• Extinction and Loss of Species Lizards

Snake-eyed skink
Azure-tailed skink
USGS
USGS
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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.
• The primary loss of domestic animals
• -poultry

Department of land and natural resources State
of Hawaii ALIEN SPECIES
USGS
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What Is Being Done To Control Damage by theBrown
Tree Snake?

• Wildlife Services (WS)
• Part of the U.S. Department of Agricultures
  (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
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Benefits
Guam

• Introduced small mammals
• - rats
• Less numerous than they were before the arrival
  of the Brown Tree Snake

www.answers.com
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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 Guams 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.

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Amazing Arboreal Abilities Danger to bats and
birds
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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.

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Captured Brown Tree Snake
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An Ecological Risk Assessment of Nonnative Boas
andPythons 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.

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An Ecological Risk Assessment of Nonnative Boas
andPythons as Potentially Invasive Species in
the United States

• These are the numbers for snakes legally
• imported into the United States!

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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.

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Fumigation is used as a way of control
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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.

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Toward a comprehensive information system to
assistinvasive 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 PBINs 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.

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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
  - Dolls Eye

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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.
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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

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Thank You