1. Brown Tree Snake
Boiga irregularis
Sanngeeta Macko
Giovana Olivera

2. Introduction Northern Australia’s ‘‘Doll’s 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

3. USGS

4. Geographic Distribution
Australia – Native
Papua New Guinea – Native
Solomon Islands – Native
Guam – Introduced
USGS

5. Guam Invasive 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

6. 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

7. Impact on Wildlife Guam
Caused extinction or extirpation of 13 bird species
Micronesian kingfisher
Guam flycatcher
USGS
USGS

8. 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

9. Impact on Wildlife Guam Extinction and Loss of Species : Lizards
Snake-eyed skink
Azure-tailed skink
USGS
USGS

10. 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

11. 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

12. Benefits Guam Introduced small mammals - rats
Less numerous than they were before the arrival of the Brown Tree Snake

13. 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.

14. Amazing Arboreal Abilities – Danger to bats and birds

15. 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.

16. Captured Brown Tree Snake

17. 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.

18. 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!

19. 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.

20. Fumigation is used as a way of control

21. 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.

22. 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.

23. 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”

24. 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):
Reed, Robert N. "An Ecological Risk Assessment of Nonnative Boas and Pythons as Potentially Invasive Species in the United States." Risk Analysis 25 (2005):
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):
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):
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):

25. Work Cited Pictures http://www.aphis.usda.gov/lpa/pubs/btsbro.pdf

26. Thank You