Degradation of the crocodile population in the Olifants River Gorge of Kruger National Park, South Africa

Aquatic Conservation: Marine and Freshwater Ecosystems

Volumn 21, Issue 2, 2011, Pages 155-164

  Ferreira, Sam M ^a   Pienaar, Danie ^a  

^a MARINE AND COASTAL MANAGEMENT   (South Africa)

Author keywords

Abundance; Aerial surveys; Availability bias; Detectability bias; Disease; Population growth; Spot light counts

Indexed keywords

ABUNDANCE; CORRECTION; CROCODILIAN; DEMOGRAPHY; ECOSYSTEM RESILIENCE; GROWTH RATE; HABITAT FRAGMENTATION; POPULATION DECLINE; POPULATION GROWTH; POPULATION SIZE; RIVER SYSTEM;

KRUGER NATIONAL PARK; LETABA RIVER; LIMPOPO; OLIFANTS RIVER; SOUTH AFRICA;

ALLIGATOR; CROCODYLIDAE (ALL CROCODILES); CROCODYLUS NILOTICUS;

EID: 79952731660     PISSN: 10527613     EISSN: 10990755     Source Type: Journal    
DOI: 10.1002/aqc.1175     Document Type: Article

References (66)

1. Ashton PJ. 2010. The demise of the Nile crocodile (Crocodylus niloticus) as a keystone species for aquatic ecosystem conservation in South Africa: the case of the Olifants River. Aquatic Conservation: Marine and Freshwater Ecosystems 20: 489-493.
2. Aust P, Boyle B, Fergusson R, Coulson T. 2009. The impact of Nile crocodiles on rural livelihoods in northeastern Namibia. South African Journal of Wildlife Research 39: 57-69.
3. Bayliss P, Webb GWJ, Whitehead PJ, Dempsey K, Smith A. 1986. Estimating the abundance of saltwater crocodiles, Crocodylis porosus Schneider, in the tidal wetlands of the Northern Territory: a mark-recapture experiment to correct spotlight counts to absolute numbers, and the calibration of helicopter and spotlight counts. Australian Wildlife Research 13: 309-320.
4. Bishop JM, Leslie AJ, Bourquin SL, O'Ryan C. 2009. Reduced effective population size in an overexploited population of the Nile crocodile (Crocodylus niloticus). Biological Conservation 142: 2335-2341.
5. Bradshaw CJA, Brook BW. 2005. Disease and the devil: density-dependent epidemiological processes explain historical population fluctuations in the Tasmanian devil. Ecography 28: 181-190.
6. Brandt LA. 1991. Long-term changes in a population of Alligator mississippiensis in South Carolina. Journal of Herpetology 25: 419-424.
7. Campos Z, Mourao G, Coutinho M. 1995. Night-light counts, size structures and sex ratios in wild populations of Yacare caiman (Caiman crocodilus yacare) in the Brazilian Pantanal. Vida Silvestre Neotropical 4: 46-50.
8. Carvan MJ, Incardona JP, Rise ML. 2008. Meeting the challenges of aquatic vertebrate ecotoxicology. BioScience 58: 1015-1025.
9. Caughley G. 1974. Bias in aerial survey. Journal of Wildlife Management 41: 605-615.
10. Chao A, Pan HY, Chiang SC. 2008. The Petersen-Lincoln estimator and its extension to estimate the size of a shared population. Biometrical Journal 50: 957-970.
11. Cherkiss MS, Mazzotti FJ, Rice KG. 2006. Effects of shoreline on visibibility of American crocodiles (Crocodylus acutus) during spotlight surveys. Herpetological Review 37: 37-40.
12. Corkrey R, Brooks S, Lusseau D, Parsons K, Durban JW, Hammond PS, Thompson PM. 2008. A Bayesian capture-recapture population model with simultaneous estimation of heterogeneity. Journal of the American Statistical Association 103: 948-960.
13. Crowl TA, Crist TO, Parmenter RR, Belovsky G, Lugo AE. 2008. The spread of invasive species and infectious disease as drivers of ecosystem change. Frontiers in Ecology and the Environment 6: 238-246.
14. Cubaynes S, Pradel R, Choquet R, Duchamp C, Gaillard J-M, Lebreton J-D, Marboutin E, Moquel C, Reboulet A, Poillit C et al. 2010. Importance of accounting for detection heterogeneity when estimating abundance: the case of French wolves. Conservation Biology 24: 621-626.
15. Da Silveira R, Magnusson WE, Thorbjarnarson JB. 2008. Factors affecting the number of caimans seen during spotlight surveys in the Mamirauá Reserve, Brazilian Amazonia. Copeia 2: 425-430.
16. Dobson A, Lodge D, Alder J, Cumming GS, Keymer J, McGlade J, Mooney H, Rusak JA, Sala O, Wolters V et al. 2006. Habitat loss, trophic collapse, and the decline of ecosystem services. Ecology 87: 1915-1924.
17. Downs CT, Greaver C, Taylor R. 2008. Body temperature and basking behaviour of Nile crocodiles (Crocodylus niloticus) during winter. Journal of Thermal Biology 33: 185-192.
18. Dunham KM, Robertson EF, Grant CC. 2004. Rainfall and the decline of a rare antelope, the tsessebe (Damaliscus lunatus lunatus), in Kruger National Park, South Africa. Biological Conservation 117: 83-94.
19. du Preez HH, van der Merwe M, van Vuuren JHJ. 1997. Bio-accumulation of selected metals in African sharptooth catfish Clarias gariepinus from the lower Olifants River, Mpumalanga, South Africa. Koedoe 40: 77-90.
20. Evans PGH, Hammond PS. 2004. Monitoring cetaceans in European waters. Mammal Review 34: 131-156.
21. Gerrodette T. 1987. A power analysis for detecting trends. Ecology 68: 1364-1372.
22. Gertenbach WPD. 1980. Rainfall patterns in the Kruger National Park. Koedoe 23: 35-43.
23. Hartley DDR. 1990. A survey of crocodile nests in Umfolozi Game Reserve. Lammergeyer 41: 1-12.
24. Hocutt CH, Loveridge JP, Hutton JM. 1992. Biotelemetry monitoring of translocated Crocodylus niloticus in Lake Ngezi, Zimbabwe. Journal of Zoology, London 226: 231-242.
25. Huchzermeyer FW. 2002. Diseases of farmed crocodiles and ostriches. Revue Scientifique et Technique De L Office International Des Epizooties 21: 265-276.
26. Hutton JM, Woolhouse MEJ. 1989. Mark-recapture to assess factors affecting the proportion of a Nile crocodile population seen during spotlight counts at Ngezi, Zimbabwe, and the use of spotlight counts to monitor crocodile abundance. Journal of Applied Ecology 26: 381-395.
27. Jacobsen NHG. 1984. The distribution and status of crocodile populations in the Transvaal outside the Kruger National Park. Biological Conservation 29: 191-200.
28. Karr JR, Dudley DR. 1981. Ecological perspective on water quality goals. Environmental Management 5: 55-68.
29. Kay WR. 2004. Movements and home ranges of radio-tracked Crocodylus porosus in the Cambridge Gulf region of Western Australia. Wildlife Research 31: 495-508.
30. Kofron CP. 1990. The reproductive cycle of the Nile crocodile (Crocodylus niloticus). Journal of Zoology, London 221: 477-488.
31. Kofron CP. 1992. Status and habitats of the three African crocodiles in Liberia. Journal of Tropical Ecology 8: 265-273.
32. Kofron CP. 1993. Behavior of Nile crocodiles in a seasonal river in Zimbabwe. Copeia 1993: 463-469.
33. Kroger R, Rogers KH. 2005. Roan (Hippotragus equinus) population decline in Kruger National Park, South Africa: influence of a wetland boundary. European Journal of Wildlife Research 51: 25-30.
34. Leslie AJ, Spotila JR. 2001. Alien plant threatens Nile crocodile (Crocodylus niloticus) breeding in Lake St. Lucia, South Africa. Biological Conservation 98: 347-355.
35. Letcher BH, Horton GE. 2008. Seasonal variation in size-dependent survival of juvenile Atlantic salmon (Salmo salar): performance of multi-state capture-mark-recapture models. Canadian Journal of Fisheries and Aquatic Sciences 65: 1649-1666.
36. Letnic M, Connors G. 2006. Changes in the distribution and abundance of saltwater crocodiles (Crocodylus porosus) in the upstream, freshwater reaches of rivers in the Northern Territory, Australia. Wildlife Research 33: 529-538.
37. Martin S. 2008. Global diversity of crocodiles (Crocodilia, Reptilia) in freshwater. Hydrobiologia 595: 587-591.
38. Mazzotti FJ, Best GR, Brandt LA, Cherkiss MS, Jeffery BM, Rice KG. 2009. Alligators and crocodiles as indicators for restoration of Everglades ecosystems. Ecological Indicators 9S: 137-149.
39. McDonald RA, Delahay RJ, Carter SP, Smith GC, Cheeseman CL. 2008. Perturbing implications of wildlife ecology for disease control. Trends in Ecology and Evolution 23: 53-56.
40. Messel H, Vorlicek GC. 1987. A population model for Crocodylus porosus in the tidal waterways of Northern Australia: management implications. In Wildlife Management: Crocodiles and Alligators, Webb GJW, Manolis SC, Whitehead PJ (eds). Surrey Beany & Sons Ltd in association with the Conservation Commission of the Northern Territory: Darwin, Australia; 189-198.
41. Mourão GM, Bayliss P, Coutinho ME, Abercrombie CL, Arruda A. 1994. Test of an aerial survey from caiman and other wildlife in the Pantanal, Brazil. Wildife Society Bulletin 22: 50-56.
42. Musambachime MC. 1987. The fate of the Nile crocodile in African waterways. African Affairs 86: 197-207.
43. Myburgh J. 2008. Crocodile crisis in the Kruger National Park. OP News 8: 13.
44. Myburgh J, Botha A. 2009. Decline in herons along the lower Olifants River - could pansteatitis be a contributing factor? Vet News March: 20-23.
45. Osthoff G, Hugo A, Bouwman H, Buss P, Govender D, Joubert CC, Swarts JC. 2010. Comparison of the lipid properties of captive, healthy wild, and pansteatitis-affected wild Nile crocodiles (Crocodylus niloticus). Comparative Biochemistry and Physiology, Part A 155: 64-69.
46. Pacheco LF. 1996. Effects of environmental variables on black caiman counts in Bolivia. Wildlife Society Bulletin 24: 44-49.
47. Plowright RK, Sokolow SH, Gorman ME, Daszak P, Foley JE. 2008. Causal inference in disease ecology: investigating ecological drivers of disease emergence. Frontiers in Ecology and the Environment 6: 420-429.
48. Råberg L, Sim D, Read AF. 2007. Disentangling genetic variation for resistance and tolerance to infectious diseases in animals. Science 318: 812-814.
49. Redfern JV, Viljoen PC, Kruger JM, Getz WM. 2002. Biases in estimating population size from aerial census: a case study in the Kruger National Park, South Africa. South African Journal of Science 98: 455-461.
50. Robinson J, Avenant-Oldewage A. 1997. Chromium, copper, iron and manganese bioaccumulation in some organs and tissues of Oreochromis mossambicus from the lower Olifants River inside the Kruger National Park. Water SA 23: 387-403.
51. Roux DJ, Nel JL, Ashton PJ, Deacon AR, de Moor FC, Hardwick D, Hill L, Kleynhans CJ, Maree GA, Moolman J, Scholes RJ. 2008. Designing protected areas to conserve riverine biodiversity: lessons from a hypothetical redesign of the Kruger National Park. Biological Conservation 141: 100-117.
52. Schutte IC. 1986. The general geology of the Kruger National Park. Koedoe 29: 13-38.
53. Schreiber SJ. 2010. Interactive effects of temporal correlations, spatial heterogeneity and dispersal on population persistence. Proceedings of the Royal Society B - Biological Sciences 277: 1907-1944.
54. Scott MC, Hall LW. 1997. Fish assemblages as indicators of environmental degradation in Maryland Coastal Plain Streams. Transactions of the American Fisheries Society 126: 349-360.
55. Seymore T. 1994. Bioaccumulation of metals in Barbus marequensis from the Olifants River, Kruger National Park and lethal levels of manganese to juvenile Oreochromis mossambicus. MSc thesis, RAU, Johannesburg.
56. Shirley MH, Oduro W, Beibro HY. 2009. Conservation status of crocodiles in Ghana and Cote-d'Ivoire, West Africa. Oryx 43: 136-145.
57. Slooten E, Dawson SM, Rayment WJ. 2004. Aerial surveys for coastal dolphins: abundance of Hector's dolphins off the South Island west coast, New Zealand. Marine Mammal Science 20: 477-490.
58. Strauss M, Botha H, van Hoven W. 2008. Nile crocodile Crocodylus niloticus telemetry: observations on transmitter attachment and longevity. South African Journal of Wildlife Research 38: 189-192.
59. Swanepoel DGJ. 1999. Movements, nesting and the effects of pollution on the nile crocodile Crocodylus niloticus in the Olifants River, Kruger National Park. MSc thesis, University of Natal, South Africa.
60. Thorbjarnarson JB. 1996. Reproductive characteristics of the Order Crocodylia. Herpetologica 52: 8-24.
61. Thorbjarnarson J, Platt SG, Khaing UST. 2000. A population survey of the estuarine crocodile in the Ayeyarwady Delta, Myanmar. Oryx 34: 317-324.
62. van Vuuren L. 2009. Experts unite to save abused river from extinction. Water Wheel 8: 14-17.
63. Venter FJ, Scholes RJ, Eckhardt HC. 2003. The abiotic template and its associated vegetation pattern. In The Kruger Experience: Ecology and Management of Savanna Heterogeneity, du Toit JT, Rogers KH, Biggs HC (eds). Island Press: Washington, DC; 85-129.
64. Webb GJW, Smith AMA. 1987. Life history parameters, population dynamics and the management of crocodiles. In Wildlife Management: Crocodiles and Alligators, Webb GJW, Manolis SC, Whitehead PJ (eds). Surrey Beany & Sons Ltd in association with the Conservation Commission of the Northern Territory: Darwin, Australia; 177-187.
65. Webb GJW, Buckworth R, Manolis SC. 1983. Crocodylus johnstoni in the McKinlay River Area, N.T. III. Growth, movement and the population age structure. Australian Wildlife Research 10: 383-401.
66. Wormald CL, Steele MA. 2008. Testing assumptions of mark-recapture theory in the coral reef fish Lutjanus apodus. Journal of Fish Biology 73: 498-509.