456 



Non-ntitivc Species — Our Living Resimnex 



For further information: 



T.H- Fntts 



National Biological Service 



National Museum of 



Natural History 



MRC 111 



10th and Constitution, NW 



Washinaton. DC 2056(1 



reptile species present in Hawaii (all intro- 

 duced). 8 are known as native or introduced 

 species on Guam. Many of these introduced 

 species are locally abundant and attain high 

 population levels in Hawaii. All these factors 

 show how capable the brown tree snake is in 

 exploiting elements of the native and introduced 

 fauna of Hawaii and in attaining high popula- 

 tion levels in Hawaii and on other Pacific 

 islands on which it may become established. 



The effects of the brown tree snake extend 

 beyond ecological damages; the snakes fre- 

 quently climb on electrical transmission lines 

 causing faults and disrupting electrical supplies, 

 enter urban and residential areas where they 

 consume poultry and pets, and bite humans 

 causing trauma and serious health risks for 

 small children (Fritts 1988). 



References 



Conry, P.J. mSX, High nest predation by hrown tree snakes 

 on Guam. Condor 90:478-482. 



Enghring. J.. andTH. Fritts. 1988. Demise of an insular avi- 

 fauna: the brown tree snake on Guam. Transactions of the 

 Western Section of the Wildlife Society 24:.^ 1 -.^7. 



E-ngbnng. J., and F.L. Ramsey. 1984. Distribution and abun- 

 dance of the forest birds of Guam: results of a 1981 sur- 

 vey. U.S. Fish and Wildlife Service FWS/OBS 84(20). 54 

 pp. 



Engbring. J.. F.L. Ramsey, and V.J. Wildman. 1986. 

 Micronesian forest bird survey. 1982: Saipan. Tinian. 

 Agiguan, and Rota. U.S. Fish and Wildlife Service. 

 Honolulu. HI. 143 pp. 



Fntts. T.H, 1987. Movements of snakes via cargo in the 

 Pacific region, 'Elepaio 47:17-18, 



Fntts, T,H, 1988, The brown tree snake, Boigu irregularis, a 

 threat to Pacific Islands, U,S, Fish and Wildlife Service 

 Biological Rep, 88(,31 ), 36 pp. 



McCoid, M,J,. and D,W, Stinson, 1991, Recent snake sight- 

 ings in the Mariana Islands, 'Elepaio 51:36-37, 



Moulton, M,P,, and S.L, Pimm, 1986, Species introductions 

 to Hawaii, Pages 231-249 in H,A, Mooney and J, A, 

 Drake, eds. Ecology of biological invasions of North 

 Amenca and Hawaii. Springer- Verlag, New York, 



Rodda. G,H,, T,H, Fritts, and RJ, Conry, 1992, Origin and 

 population growth of the brown tree snake. Boiga irreg- 

 uliiris. on Guam. Pacific Science 46:46-57, 



Rodda. G.H., T.H, Fritts, and J.D, Reichel, 1991 , The distri- 

 butional patterns of reptiles and amphibians in the 

 Manana Islands, Micronesica 24:195-210, 



Savidge. J, A, 1987, Extinction of an island forest avifauna 

 by an introduced snake. Ecology 68:660-668, 



Savidge, J, A, 1988, Food habits of Boiga irregularis, an 

 introduced predator on Guam. Journal of Herpetology 

 22:275-282, 



U,S. Department of the Intenor, 1990, Endangered and 

 threatened species recovery program. Report to 

 Congress, Washington, DC, 406 pp. 



Wiles. G.J. 1987, Current research and future management 

 of Marianas fruit bats (Chiroptera:Pteropidae) on Guam, 

 Australian Mammalogy 10:93-95, 



Wild Horses 

 and Burros on 

 Public Lands 



by 



Tom Pogacnik 



Bureau of Land Management 



On December 15, 1971, Congress passed 

 legislation to protect, manage, and control 

 wild horses (Equus cahaUus) and burros (£. asi- 

 luts) on public lands. The Wild Free-Roaming 

 Horses and Burros Act (Public Law 92-193) 

 described these animals as fast-disappearing 

 symbols of the historic and pioneer spirit of the 

 West. The Bureau of Land Management (BLM) 

 and the U.S. Forest Service are charged with 

 administering the law, which specifies how wild 

 horses and burros are to be managed on the 

 range and how excess animals are to be dis- 

 posed. Section 3. (a) requires the Secretary of 

 the Interior to manage wild free-roaming horses 

 and burros in a manner designed to achieve and 

 maintain a thriving natural ecological balance 

 on public lands. This section also specifies 

 requirements for inventorying, monitoring, 

 establishing appropriate management levels, 

 making removals, placing excess animals, and 

 establishing criteria for destruction of animals. 

 Although these animals were once consid- 

 ered endangered by the nearly unrestrained 

 onslaught of the mustangers and others, they 

 have thrived under federal protection (Fig. I). 

 With few predators and with protection from 

 humans, wild horse and burro populations on 

 BLM-administered lands (where most of the 

 animals are located) quickly grew until control 

 of the populations and the effect on their habitat 

 became a major concern. 



Wild horses (Equus caballus). 



The act requires that BLM maintain a cur- 

 rent inventory of wild horses and burros on cer- 

 tain public lands. At present, BLM censuses 

 each of the 196 herd-management areas on a 

 rotating basis, usually every 3 years, using cen- 

 sus techniques based on research published by 

 the National Academy of Sciences (1982). 

 Censuses in 1993 identified a nationwide popu- 

 lation of 46,500 wild horses and burros (Fig. 2), 

 Accuracy for the 1993 census ranged from 85% 

 to 99% on wild horses and 75% to 88% on wild 

 burros. 



