Effects of road mortality and mitigation measures on amphibian populations

Conservation Biology

Volumn 27, Issue 4, 2013, Pages 657-668

  Beebee, Trevor J C ^a  

^a Amphibian and Reptile Conservation Trust   (United Kingdom)

Author keywords

Mitigation; Population; Road mortality; Wildlife crossings

Indexed keywords

AMPHIBIAN; CONSERVATION MANAGEMENT; LIFE HISTORY TRAIT; MIGRATION; MITIGATION; MORTALITY; NATURE-SOCIETY RELATIONS; POPULATION VIABILITY ANALYSIS; ROADKILL;

AMPHIBIA; ANIMAL; CRUCES PARA FAUNA SILVESTRE; ENVIRONMENTAL PLANNING; ENVIRONMENTAL PROTECTION; METHODOLOGY; MITIGACIÓN; MITIGATION; MORTALIDAD EN CARRETERAS; MORTALITY; PHYSIOLOGY; POBLACIÓN; POPULATION; REVIEW; ROAD MORTALITY; STATISTICS; TRAFFIC ACCIDENT; TRAFFIC AND TRANSPORT; WILDLIFE CROSSINGS;

CRUCES PARA FAUNA SILVESTRE; MITIGACIÓN; MITIGATION; MORTALIDAD EN CARRETERAS; POBLACIÓN; POPULATION; ROAD MORTALITY; WILDLIFE CROSSINGS;

ACCIDENTS, TRAFFIC; AMPHIBIANS; ANIMALS; CONSERVATION OF NATURAL RESOURCES; ENVIRONMENT DESIGN; MORTALITY; TRANSPORTATION;

AMPHIBIA; ANIMALIA;

EID: 84880703554     PISSN: 08888892     EISSN: 15231739     Source Type: Journal    
DOI: 10.1111/cobi.12063     Document Type: Review

References (119)

1. Amos, W., and A. Balmford. 2001. When does conservation genetics matter? Heredity 87:257-265.
2. Arens, P., T. Van der Sluis, W. P. C. Van't Westende, B. Vosman, C. C. Vos, and M. J. M. Smulders. 2007. Genetic population differentiation and connectivity among fragmented moor frog (Rana arvalis) populations in the Netherlands. Landscape Ecology 22:1489-1500.
3. Arnold, N., and D. Ovenden. 2002. A field guide to reptiles and amphibians of Britain and Europe, 2nd edition. HarperCollins, London.
4. Ashley, E. P., and J. T. Robinson. 1996. Road mortality of amphibians, reptiles and other wildlife on the long point causeway, Lake Erie, Ontario. Canadian Field-Naturalist 110:403-412.
5. Attademo, A. M., P. M. Peltzer, R. C. Lajmanovich, G. Elberg, C. Junges, L. C. Sanchez, and A. Bassó. 2011. Wildlife vertebrate mortality in roads from Santa Fe Province, Argentina. Revista Mexicana de Biodiversidad 82:915-925.
6. Bouchard, J., A. T. Ford, F. E. Eigenbrod, and L. Fahrig. 2009. Behavioral responses of northern leopard frogs (Rana pipiens) to roads and traffic: implications for population persistence. Ecology and Society http://www.ecologyandsociety.org/vol14/iss2/art23/.
7. Brehm, K. 1989. The acceptance of 0.2-metre tunnels by amphibians during their migration to the breeding site. Pages 29-42 in T. E. S. Langton, editor. Amphibians and roads. ACO Polymer Products, United Kingdom.
8. Cairo, S. L., and S. M. Zalba. 2007. Effects of a paved road on mortality and mobility of red bellied toads (Melanophryniscus sp.) in Argentinean grasslands. Amphibia-Reptilia 28:377-385.
9. Carr, L. W., and L. Fahrig. 2001. Effect of road traffic on two amphibian species of differing vagility. Conservation Biology 15:1071-1078.
10. Carrier, J-A., and T. J. C. Beebee. 2003. Recent, substantial and unexplained declines of the common toad Bufo bufo in lowland England. Biological Conservation 111:395-399.
11. Carvalho, F., and A. Mira. 2011. Comparing annual vertebrate road kills over two time periods, 9 years apart: a case study in Mediterranean farmland. European Journal of Wildlife Research 57:157-174.
12. Clevenger, A. P., M. McIvor, D. McIvor, B. Chruszcz, and K. Gunson. 2001. Tiger salamander, Ambystoma tigrinum, movements and mortality on the trans-Canada highway in southwestern Alberta. Canadian Field-Naturalist 115:199-204.
13. Coleman, J. L., N. B. Ford, and K. Herriman. 2008. A road survey of amphibians and reptiles in a bottomland hardwood forest. Southeastern Naturalist 7:339-348.
14. Conant, R., and J. T. Collins. 1998. A field guide to the reptiles and amphibians of eastern and central North America. 3rd edition. Petersen Field Guides, Singapore, Republic of Singapore.
15. Cooke, A. S. 2011. The role of road traffic in the near extinction of common toads (Bufo bufo) in Ramsey and Bury. Nature in Cambridgeshire 53:45-50.
16. Coulson, G. 1982. Road kills: wheels and wildlife. Wildlife Australia 22:26-28.
17. Crosby, M. K. A., L. E. Licht, and J. Z. Fu. 2009. The effect of habitat fragmentation on finescale population structure of wood frogs (Rana sylvatica). Conservation Genetics 10:1707-1718.
18. Da Silva, M. O., I. S. de Oliveira, M. W. Cardoso, and V. Graf. 2007. Road kills impact over the herpetofauna of Atlantic forest PR-340, Antonina, Pananá. Acta Biológica Paranaense 36:103-122.
19. Dai, Q., and Y. Wang. 2011. Effect of road on the distribution of amphibians in wetland area test with model-averaged prediction. Polish Journal of Ecology 59:381-389.
20. Dexel, R. 1989. Investigations into the protection of migrant amphibians from the threats from road traffic in the Federal Republic of Germany: a summary. Pages 75-80 in T. E. S. Langton, editor. Amphibians and roads. ACO Polymer Products Ltd., UK.
21. Dodd, C. K., W. J. Barichivich, and L. L. Smith. 2004. Effectiveness of a barrier wall and culverts in reducing wildlife mortality on a heavily travelled highway in Florida. Biological Conservation 118:619-631.
22. Duff, J. P., K. Colville, J. Foster, and N. Dumphreys. 2011. Mass mortality of great crested newts (Triturus cristatus) on ground treated with road salt. Veterinary Record 168:282.
23. Eigenbrod, F., S. J. Hecnar, and L. Fahrig. 2008a. The relative effects of road traffic and Forest cover on anuran populations. Biological Conservation 141:35-46.
24. Eigenbrod, F., S. J. Hecnar, and L. Fahrig. 2008b. Accessible habitat: an improved measure of the effects of habitat loss and roads on wildlife populations. Landscape Ecology 23:159-168.
25. Eigenbrod, F., S. J. Hecnar, and L. Fahrig. 2009. Quantifying the road-effect zone: threshold effects of a motorway on anuran populations in Ontario, Canada. Ecology & Society http://www.ecologyandsociety.org/vol14/iss1/art24/.
26. Eionet. 2012. European topic centre on inland, coastal and marine waters. Available from http://icm.eionet.europa.eu (accessed June 2012).
27. Elzanowski, A., J. Ciesiolkewicz, M. Kaczor, J. Radwańska, and R. Urban. 2009. Amphibian road mortality in Europe: a meta-analysis with new data from Poland. European Journal of Wildlife Research 55:33-43.
28. Fahrig, L., J. H. Pedlar, S. E. Pope, P. D. Taylor, and J. F. Wegner. 1995. Effect of road traffic on amphibian density. Biological Conservation 73:177-182.
29. Findlay, C. S., and J. Bourdages. 2000. Response time of wetland biodiversity to road construction on adjacent lands. Conservation Biology 14:86-94.
30. Findlay, C. S., and J. Houlahan. 1997. Anthropogenic correlates of species richness in southeastern Ontario wetlands. Conservation Biology 11:1000-1009.
31. Froglife. 2012. Toads on roads. Froglife, Peterborough, Cambridgeshire. Available from http://www.froglife.org/toadsonroads/figures.htm (accessed June 2012).
32. Frost, D. R., et al. 2006. The amphibian tree of life. Bulletin of the American Museum of Natural History 297:1-313.
33. Fuellhaas, U., C. Klemp, A. Kordes, H. Ottersberg, M. Pirmann, A. Thiessen, C. Tschoetschel, and H. Zucchi. 1989. Investigations on road victims of birds mammals amphibians and reptiles. Bietraege zur Naturkunde Niedersachsens 42:129-147.
34. Gerow, K., N. C. Kline, D. E. Swann, and M. Pokorny. 2010. Estimating annual vertebrate mortality on roads at Saguaro National Park, Arizona. Human-Wildlife Interactions 4:283-292.
35. Gibbs, J. P., and W. G. Shriver. 2005. Can road mortality limit populations of pond-breeding amphibians? Wetlands, Ecology & Management 13:281-289.
36. Glista, D. J., T. L. DeVault, and J. A. DeWoody. 2008. Vertebrate mortality predominantly impacts amphibians. Herpetological Conservation & Biology 3:77-87.
37. Glista, D. J., T. L. DeVault, and J. A. DeWoody. 2009. A review of mitigation measures for reducing wildlife mortality on roadways. Landscape & Urban Planning 91:1-7.
38. Goldingay, R. L., and B. D. Taylor. 2006. How many frogs are killed on a road in north-east New South Wales? Australian Zoologist 33:332-336.
39. Gopi Sundar, G. S. 2004. Mortality of herpetofauna, birds and mammals due to vehicular traffic in Etawah District, Uttar Praedesh, India. Journal of the Bombay Natural History Society 101:392-398.
40. Goransson, G., J. Karlsson, and A. Lindgren. 1976. Road mortality in the hedgehog Erinaceus europaeus in southern Sweden. Fauna Och Flora Naturhistoriska Riksmuseet 71:1-6.
41. Gryz, J., and D. Krauze. 2008. Mortality of vertebrates on a road crossing the Biebrza valley (NE Poland). European Journal of Wildlife Research 54:709-714.
42. Gu, H., Q. Dai, Q. Wang, and Y. Wang. 2011. Factors contributing to amphibian road mortality in a wetland. Current Zoology 57:768-774.
43. Hartel, T., C. I. Moga, K. Öllerer, and M. Puky. 2009. Spatial and temporal distribution of amphibian road mortality with a Rana dalmatina and Bufo bufo predominance along the middle section of the Târnava Mare basin, Romania. North-Western Journal of Zoology 5:130-141.
44. Hartel, T., O. Schweiger, K. Öllerer, D. Cogãlniceanu, and J. W. Arntzen. 2010. Amphibian distribution in a traditionally managed rural landscape of Eastern Europe: probing the effect of landscape composition. Biological Conservation 143:1118-1124.
45. Hels, T., and E. Buchwald. 2001. The effect of road kills on amphibian populations. Biological Conservation 99:331-340.
46. Herden, C., J. Rassmus, and R. Schweigert. 1998. Seasonal migration patterns and roadkills of amphibians: results of a study at a road near Rumohr (Schleswig-Holstein). Faunistisch-Oekologische Mitteilungen 7:417-436.
47. Hilty, J. A., W. Z. Lidicker, and A. M. Merenlender. 2006. Corridor ecology. Island Press, Washington, D.C.
48. Hitchings, S. P., and T. J. C. Beebee. 1997. Genetic substructuring as a result of barriers to gene flow in urban Rana temporaria (common frog) populations: implications for biodiversity conservation. Heredity 78:117-127.
49. Hitchings, S. P., and T. J. C. Beebee. 1998. Loss of genetic diversity and fitness in common toad (Bufo bufo) populations isolated by inimical habitat. Journal of Evolutionary Biology 11:269-283.
50. Hodson, N. L. 1966. A survey of road mortality in mammals (and including data for grass snake and common frog). Journal of Zoology 148:576-579.
51. Holderegger, R., and M. Di Giulio. 2010. The genetic effects of roads: a review of empirical evidence. Basic and Applied Ecology 11:522-531.
52. Holisova, V., and R. Obtel. 1986. Vertebrate casualties on a Moravian road. Prirodovedne Prace Ustavu Ceskoslovenske Akademie Ved v Brne 20:1-44.
53. Hoskin, C. J., and M. W. Goosem. 2010. Road impacts on abundance, call traits, and body size of rainforest frogs in northeast Australia. Ecology & Society: http://www.ecologyandsociety.org/vol15/iss3/art15/.
54. Houlahan, J. E., and C. S. Findlay. 2003. The effects of adjacent land use on wetland Amphibian species richness and community composition. Canadian Journal of Fisheries & Aquatic Sciences 60:1078-1094.
55. Jackson, S. D., and T. F. Tyning .1989. Effectiveness of drift fences and tunnels for moving spotted salamanders Ambystoma tigrinum under roads. Pages 93-99 in T.E.S. Langton, editor. Amphibians and roads. ACO Polymer Products, United Kingdom.
56. Jochimsen, D. M., C. R. Peterson, K. M. Andrews, and J. W. Gibbons. 2004. A literature review of the effects of roads on amphibians and reptiles and the measures used to minimize those effects. Idaho Fish and Game Department, Boise.
57. Johansson, M., C. R. Primmer, J. Sahisten, and J. Merila. 2005. The influence of landscape structure on occurence, abundance and genetic diversity of the common frog, Rana temporaria. Global Change Biology 11:1664-1679.
58. Jolivet, R., M. Antionazza, C. Strehler-Perrin, and A. Gander. 2008. Impact of road mitigation measures on amphibian populations: a stage-class population mathematical model. Cornell University Library, Ithaca, New York. Available from http://arxiv.org/abs/0806.4449 (accessed February 2013).
59. Karraker, N. E., J. P. Gibbs, and J. R. Vonesh. 2008. Impacts of road deicing salt on the demography of vernal-pool breeding amphibians. Ecological Applications 18:723-734.
60. Langen, T. A., A. Machniak, E. K. Crowe, C. Mangan, D. F. Marker, N. Liddle, and B. Roden. 2007. Methodologies for surveying herpetofauna mortality on rural highways. Journal of Wildlife Management 71:1361-1368.
61. Langen, T. A., K. M. Ogden, and L. L. Schwarting. 2009. Predicting hotspots of herpetofauna road mortality along highway networks. Journal of Wildlife Management 73:104-114.
62. Langton, T. E. S. 1989a. Tunnels and temperature: results from a study of a drift fence and tunnel system for amphibians at Henley-on-Thames, Buckinghamshire, England. Pages 145-152 in T. E. S. Langton, editor. Amphibians and roads. ACO Polymer Products, Peterb Ltd., United Kingdom.
63. Langton, T. E. S. 1989b. Reasons for preventing amphibian mortality on roads. Pages 75-80 in T.E.S. Langton, editor. Amphibians and roads. ACO Polymer Products, Peterborough, Cambridgeshire.
64. Lesbarrères, D., and L. Fahrig. 2012. Measures to reduce population fragmentation by roads: What has worked and how do we know? Trends in Ecology & Evolution 27:374-380.
65. Lesbarrères, D., M. S. Fowler, A. Pagano, and T. Lodé. 2010. Recovery of anuran community diversity following habitat replacement. Journal of Applied Ecology 47:148-156.
66. Lesbarrères, D., A. Pagano, and T. Lodé. 2003. Inbreeding and road effect zone in a Ranidae: the case of agile frog, Rana dalmatina Bonaparte, 1840. Comptes Rendus 326:S68-S72.
67. Lesbarrères, D., T. Lodé, and J. Merila. 2004. What type of amphibian tunnel could reduce road kills? Oryx 38:220-223.
68. Lesbarrères, D., C. R. Primmer, T. Lodé, and J. Merila. 2006. The effects of 20 years of highway presence on the genetic structure of Rana dalmatina populations. Ecoscience 13:531-538.
69. Linck, M. H. 2000. Reduction in road mortality in a northern leopard frog population. Journal of the Iowa Academy of Sciences 107:209-211.
70. Lodé, T. 2000. Effect of a motorway on mortality and isolation of wildlife populations. Ambio 29:163-166.
71. Lustrat, P. 2005. Etude de l'efficacite des crapauds installes sous la rd 104A Sorques (77). Nature Recherche, Villiers, France.
72. Marsh, D. M. 2007. Edge effects of gated and ungated roads on terrestrial salamanders. Journal of Wildlife Management 71:389-394.
73. Marsh, D. M., R. B. Page, T. J. Hanlon, R. Corritone, E. C. Little, D. E. Seifert, and P. R. Cabe. 2008. Effects of roads on patterns of genetic differentiation in red-backed salamanders, Plethodon cinereus. Conservation Genetics 9:603-613.
74. Mazerolle, M. J. 2004. Amphibian road mortality in response to nightly variations in traffic intensity. Herpetologica 60:45-53.
75. Mazerolle, M. J., M. Huot, and M. Gravel. 2005. Behavior of amphibians on the road in response to car traffic Herpetologica 61:380-388.
76. McCaffer, K. R. 1973. Road kills show trends in Wisconsin deer populations. Journal of Wildlife Management 37:212-216.
77. Meinig, H. 1989. Experience and problems with a toad tunnel system in the Mittelbirge region of West Germany. Pages 59-66 in T. E. S. Langton, editor. Amphibians and roads. ACO Polymer Products, Peterborough, Cambridgeshire.
78. Noel, S., M. Ouellet, P. Galois, and F. J. Lapointe. 2007. Impact of urban fragmentation on the genetic structure of the eastern red-backed salamander. Conservation Genetics 8: 599-606.
79. Nyström, P., J. Hansson, J. Månsson, M. Sundstedt, C. Reslow, and A. Broström. 2007. A documented amphibian decline over 40 years: possible causes and implications for species recovery. Biological Conservation 138:399-411.
80. Orlowski, G. 2007. Spatial distribution and seasonal pattern in road mortality of the common toad Bufo bufo in an agricultural landscape of south-western Poland. Amphibia-Reptilia 28:25-31.
81. Orlowski, G., J. Ciesiolkiewicz, M. Kaczor, J. Radwańska and A. Zywicka. 2008. Species composition and habitat correlates of amphibian roadkills in different landscapes of south-western Poland. Polish Journal of Ecology 56:659-671.
82. Oxley, D. J., M. B. Fenton, and G. R. Carmondy. 1974. Effects of roads on populations of small mammals. Journal of Applied Ecology 11:51-59.
83. Pagnucco, K. S., C. A. Paszkowski, and G. J. Scrimgeour. 2012. Characterizing movement patterns and spatio-temporal use of under-road tunnels by long-toed salamanders in Waterton Lakes National Park, Canada Copeia 2012:331-340.
84. Parris, K. M. 2006. Urban amphibian assemblages as metacommunities. Journal of Animal Ecology 75:757-764.
85. Patrick, D. A., C. M. Schalk, J. P. Gibbs, and H. W. Woltz. 2010. Effective culvert placement and design to facilitate passage of amphibians across roads. Journal of Herpetology 44:618-626.
86. Pellet, J., A. Guisan, and N. Perrin. 2004. A concentric analysis of the impact of urbanisation on the threatened European tree frog in an agricultural landscape. Conservation Biology 18:1599-1606.
87. Podloucky, R. 1989. Protection of amphibians on roads: examples and experiences from Lower Saxony. Pages 15-28 in T.E.S. Langton, editor. Amphibians and roads. ACO Polymer Products, Peterborough, Cambridgeshire.
88. Porej, D., M. Micacchion, and T. E. Hetherington. 2004. Core terrestrial habitat for conservation of local populations of salamanders and wood frogs in agricultural landscapes. Biological Conservation 120:399-409.
89. Puky, M. 2005. Amphibian road kills: a global perspective. Road Ecology Centre, University of California, Davis. Available from http://escolarship.org.uc/item/7j7546qv (accessed November 2012).
90. Reshetylo, O. S. and T. Mykitchak. 2008. Road mortality of amphibians (Amphibia) in Lviv region: problem status and estimating criteria. Vestnik Zoologii 42:315-323.
91. Rey, W., and A. Seitz. 1990. The influence of land use on the genetic structure of populations of the common frog Rana temporaria. Biological Conservation 54:239-250.
92. Rinehart, K. A., T. M. Donovan, B. R. Mitchell, and R. A. Long. 2009. Factors influencing occupancy patterns of eastern newts across Vermont. Journal of Herpetology 43:521-531.
93. Rowe, G., and T. J. C. Beebee. 2003. Population on the verge of a mutational meltdown? Fitness costs of genetic load for an amphibian in the wild. Evolution 57:177-181.
94. Ryser, J., and K. Grossenbacher. 1989. A survey of amphibian preservation at roads in Switzerland. Pages 75-80 in T. E. S. Langton, editor. Amphibians and roads. ACO Polymer Products Ltd., UK.
95. Rytwinski, T., and L. Fahrig. 2012. Do species life history traits explain population responses to roads? A meta-analysis. Biological Conservation 147: 87-98.
96. Safner, T., C. Miaud, O. Gaggiotti, S. Decout, D. Rioux, S. Zundel, and S. Manel. 2011. Combining demography and genetic analysis to assess the population structure of an amphibian in a human-dominated landscape. Conservation Genetics 12:161-173.
97. Salio, C., D. Paci, and C. Giacoma. 2001. Results of a 4-year project of toad conservation. Rivista di Idrobiologia 40:163-169.
98. Santos, S. M., F. Carvalho, and A. Mira. 2011. How long do the dead survive on the road? Carcass persistence probability and implications for road-kill monitoring surveys. PLOS ONE 6 DOI:10.1371/journal.pone.0025383.
99. Savage, R. M. 1935. The influence of external factors on the spawning date and migration of the common frog, Rana temporaria. Proceedings of the Zoological Society of London 2:49-98.
100. Schlupp, I., and R. Podloucky. 1994. Changes in breeding site fidelity: a combined study of conservation and behaviour in the common toad Bufo bufo. Biological Conservation 69:285-291.
101. Semlitsch, R. D., T. J. Ryan, K. Ramed, M. Chatfield, B. Drehman, N. Pekarek, M. Spath, and A. Watland. 2007. Salamander abundance along road edges and within abandoned logging roads in Appalachian forests. Conservation Biology 21:159-167.
102. Sillero, N. 2008. Amphibian mortality levels on Spanish country roads: descriptive and spatial analysis. Amphibia-Reptilia 29:337-347.
103. Skidds, D. E., F. C. Golet, P. W. C. Paton, and J. C. Mitchell. 2007. Habitat correlates of reproductive effort in wood frogs and spotted salamanders in an urbanising watershed. Journal of Herpetology 41:439-450.
104. Speybroeck, J., W. Beukema, and P.-A. Crochet. 2010. A tentative species list of the European herpetofauna (Amphibia and Reptilia): an update. Zootaxa 2492:1-27.
105. Stebbins, R. C., and R. T. Petersen. 2003. A field guide to western reptiles and amphibians. Petersen Field Guides, Singapore, Republic of Singapore.
106. Stuart, S. N., J. S. Chanson, N. A. Cox, B. E. Young, A. S. L. Rodrigues, D. L. Fischmann, and R. W. Waller. 2004. Status and trends of amphibian declines and extinctions worldwide. Science 306:1783-1786.
107. Sutherland, R. W., P. R. Dunning, and W. M. Baker. 2010. Amphibian encounter rates on roads with different amounts of traffic and urbanisation. Conservation Biology 24:1626-1635.
108. Taylor, B. D., and R. L. Goldingay. 2003. Cutting the carnage: wildlife usage of road culverts in north-east New South Wales. Wildlife Research 30:529-537.
109. Taylor, B. D., and R. L. Goldingay. 2010. Roads and wildlife: impacts, mitigation and implications for wildlife management in Australia. Wildlife Research 37:320-331.
110. Tok, C. V., D. Ayaz, and K. Çiçek. 2011. Road mortality of amphibians and reptiles in the Anatolian part of Turkey. Turkish Journal of Zoology 35:851-857.
111. Van Gelder, J. J. 1973. A quantitative approach to the mortality resulting from traffic in a population of Bufo bufo L. Oecologia 13:93-95.
112. Vargas-Salinas, F., I. Delgado-Ospina, and F. Lopez-Aranda. 2011. Amphibians and reptiles killed by motor vehicles in a sub-Andean forest in western Colombia. Caldasia 33:121-138.
113. Veysey, J. S., S. D. Mattfeldt, and K. J. Babbitt. 2011. Comparative influence of isolation, landscape, and wetland characteristics on egg-mass abundance of two pool-breeding amphibian species. Landscape Ecology 26:661-672.
114. Vos, C. C., and J. P. Chardon. 1998. Effects of habitat fragmentation and road density on the distribution pattern of the moor frog Rana arvalis. Journal of Applied Ecology 35:44-56.
115. Ward, R. L., J. T. Anderson, and J. T. Petty. 2008. Effects of road crossings on stream and streamside salamanders. Journal of Wildlife Management 72:760-771.
116. Wells, K. D. 2007. The ecology and behavioor of amphibians. University of Chicago Press, Chicago.
117. Woltz, H. W., J. P. Gibbs, and P. K. Ducey. 2008. Road crossing structures for amphibians and reptiles: informing design through behaviour analysis. Biological Conservation 141:2745-2750.
118. World Bank. 2012. Road density (km of road per 100 sq. km. of land area). World Bank, New York. Available from http://data.worldbank.org/indicator/IS.ROD.DNST.K2 (accessed June 2012).
119. Zuiderwijk, A. 1989. Amphibian and reptile tunnels in the Netherlands. Pages 67-74 in T.E.S. Langton, editor. Amphibians and Roads. ACO Polymer Products, Peterborough, Cambridgeshire.