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Rodents

Rodents comprise a major invasive species group. Chief among these species are the "commensal" rodent species (Norway rats, Rattus norvegicus, roof rats, Rattus rattus, and house mice, Mus musculus) that live in close association with humans. However, many other rodents have been accidentally or purposely introduced in various parts of the world.

Recently, a large emphasis has been placed on invasive rodent control or eradication for conservation purposes, especially on public lands. Rats have had a devastating impact on many native ecosystems, particularly remote islands where the flora and fauna have evolved in isolation from predators (Atkinson 1989). Polynesian rats (Rattus exulans) spread with early Polynesian immigrants across the Pacific basin, and roof rats (Rattus rattus) and Norway rats (Rattus norvegicus) later accompanied western explorers throughout the world (Atkinson 1985). All 3 species prey on ground-nesting sea birds on remote oceanic islands (Austin 1948, Kepler 1967, Coulter et al. 1985, Bertram 1995). Roof rats, the only 1 of the 3 species that regularly climbs trees, prey on the eggs and young of many species of forest birds (Atkinson 1977, Dunlevy et al. 2000). Rats have negative impacts on rare invertebrate fauna (Hadfield et al. 1993) and on native vegetation (Allen et al. 1994, Witmer et al. 1998) on many islands, and may help spread seeds of invasive plant species (Dunlevy et al. 2000).

Intensive efforts to control invasive rodent species for the protection of crops, stored foods, property, and human and livestock health go back many centuries. There is a long history of development and testing of methods for rodent control, including sanitation and exclusion, traps, toxicants, and delivery systems. Accomplishing a successful eradication of invasive rodents on an island involves extensive effort, compliance with environmental regulations, choosing a method, inventorying and monitoring of rodents and natural resources, nontarget hazard assessment and mitigation, and logistical planning.

Historically, many rodent eradication efforts have failed or had unintended consequences. For example, removal of invasive rats can lead to an irruption of the house mouse population or predatory species (such as brown tree snakes, Boiga irregularis, or feral cats, Felis catus) shifting their predation from rats to native. In addition to detailed planning, baseline studies may be needed to better understand the site-specific situation and to test proposed removal methods.

Summary above taken from:

TOBIN, M. E., AND M. W. FALL. 2005. Pest control: rodents. in Encyclopedia of life support systems (EOLSS): Agricultural sciences. UNESCO, Eolss Publishers, Oxford, UK. Accessed 11-21-2005. http://www.eolss.net.

WITMER, G., AND J. EISEMANN. 2005. An overview of the 2nd National Invasive Rodent Summit. Proceedings of the Wildlife Damage Management Conference 11:102-111.

Literature Cited

ALLEN, R. B., W.G. LEE, AND B. D. RANCE. 1994. Regeneration in indigenous forest after eradication of Norway rats, Breaksea Island, New Zealand. New Zealand Journal of Botany 32:429-439.

ATKINSON, I. A. E. 1989. Introduced animals and extinctions. Pages 54-79 in D. Western and M.C. Pearl, editors. Conservation for the twenty-first century. Oxford University Press, New York, New York, USA.

ATKINSON, I. A. E. 1977. A reassessment of factors, particularly Rattus rattus L., that influenced the decline of endemic forest birds in the Hawaiian Islands. Pacific Science 31:109-133.

ATKINSON, I. A. E. 1985. The spread of commensal species of Rattus to oceanic islands and their effects on island avifaunas. ages 35-81 in P.J. Moors, editor. Conservation of island birds. ICBP Technical Publication No. 3.

AUSTIN, O. L. 1948. Predation by the common rat (Rattus norvegicus) in the Cape Cod colonies of nesting terns. Bird-Banding 19:60-65.

BERTRAM, D. F. 1995. The roles of introduced rats and commercial fishing in the decline of ancient murrelets on Langara Island, British Columbia.

COULTER, M. C., F. CRUZ AND J. CRUZ. 1985. A programme to save the dark-rumped petrel, Pterodroma phaeopygia, on Floreana Island, Galapagos, Ecuador. ICBP Technical Publication No. 3.

DUNLEVY, P. A., E. W. CAMPBELL III, G. D. LINDSEY. 2000. Broadcast application of a placebo rodenticide bait in a native Hawaiian forest. International Biodeterioration & Biodegradation 45:199-208.

HADFIELD, M. G., S. E. MILLER, AND A. H. CARWILE.1993. The decimation of endemic Hawai'ian tree snails by alien predators. American Zoologist 33:610-622.

KEPLER, C. B. 1967. Polynesian rat predation on nesting Laysan albatrosses and other Pacific seabirds. Auk 84:426-430.

Witmer, G.W., E.W. Campbell, and F. Boyd. 1998. Rat management for endangered species protection in the U.S. Virgin Islands. Proceedings of the Vertebrate Pest Conference 18:281-286.