Female Agassiz’s desert tortoise activity at a wind energy facility in southern California: The influence of an El Niño event
Josh R. Ennen, Kathie Meyer, Jeffrey Lovich
DOI: 10.4236/ns.2012.41006   PDF    HTML     5,225 Downloads   9,287 Views   Citations


We compared spring-summer activity of adult female Agassiz’s Desert Tortoises (Gopherus agassizii) among three consecutive years (1997, 1998, and 1999) that differed dramatically in winter rainfall and annual plant production at a wind energy facility in the Sonoran Desert of southern California. Winter rainfall was approximately 71%, 190%, and 17% of the long-term average (October-March = 114 mm) for this area in water years (WY) 1997, 1998, and 1999, respectively. The substantial precipitation caused by an El Ni?o Southern Oscillation (ENSO) event in WY 1998 produced a generous annual food plant supply (138.2 g dry biomass/ m2) in the spring. Primary production of winter annuals during below average rainfall years (WY 1997 and WY 1999) was reduced to 98.3 and 0.2 g/m2, respectively. Mean rates of movement and mean body condition indices (mass/length) did not differ significantly among the years. The drought year following ENSO (WY 1999) was statistically similar to ENSO in every other measured value, while WY 1997 (end of a two year drought) was statistically different from ENSO using activity area, minimum number of burrows used, and percentage of non-movements. Our data suggest that female G. agassizii activity can be influenced by environmental conditions in previous years.

Share and Cite:

Ennen, J. , Meyer, K. and Lovich, J. (2012) Female Agassiz’s desert tortoise activity at a wind energy facility in southern California: The influence of an El Niño event. Natural Science, 4, 30-37. doi: 10.4236/ns.2012.41006.

Conflicts of Interest

The authors declare no conflicts of interest.


[1] Trenberth, K.E. (1997) The definition of El Ni?o. Bulletin of the American Meteorological Society, 78, 2771-2777. http://echorock.cgd.ucar.edu/cas/Trenberth/trenberth.papers/defnBAMS.pdf
[2] Stapp, P., Polis, G.A. and Sanchez, F.P. (1999) Stable isotopes reveal strong marine and El Ni?o effects on island food webs. Nature, 401, 467-469. doi:10.1038/46769
[3] Holmgren, M., Scheffer, M., Ezcurra, E., Gutiérrez, J.R. and Mohren, G.M.J. (2001) El Ni?o effects on the dynamics of terrestrial ecosystems. Trends in Ecology and Evolution, 16, 89-94. doi:10.1016/S0169-5347(00)02052-8
[4] Barber, R.T. and Chavez, F.P. (1983) Biological cones- quences of El Ni?o. Science, 222, 1203-1210. doi:10.1126/science.222.4629.1203
[5] Fauvelot, C., Cleary, D.F.R. and Menken, S.B.J. (2006) Short-term impact of disturbance on genetic diversity and structure of Indonesian populations of the butterfly Drupadia theda in East Kalimantan. Molecular Ecology, 18, 2069-2081. doi:10.1111/j.1365-294X.2006.02920.x
[6] Anderson, D.J. (1989) Differential responses of boobies and other seabirds in the Galapagos to the 1986-1987 El Ni?o-Southern Oscillation event. Marine Ecology Progress Series, 53, 209-216. doi:10.3354/meps052209
[7] Boersma, P.D. (1998) Population trends of the Galapagos Penguin: Impacts of El Ni?o and La Ni?a. The Condor, 100, 245-253. doi:10.2307/1370265
[8] Boersma, P.D. (1998) The 1997-1998 El Ni?o: Impacts on penguins. Penguin Conservation, 11, 10-11, 19.
[9] Paredes R. and Zavalaga, C.B. (1998) Overview of the effects of the El Ni?o 1997-1998 on Humboldt Penguins and other seabirds at Punta San Juan, Peru. Penguin Conservation, 11, 5-7.
[10] Valle, C.A., Cruz, F., Cruz, J.B., Merlen, G. and Coulter, M.C. (1987) The impact of the 1982-1983 El Ni?o— Southern Oscillation on seabirds in the Galapagos Islands, Ecuador. Journal of Geophysical Research, 92, 14437- 14444. doi:10.1029/JC092iC13p14437
[11] Wilson, U.W. (1991) Responses of three seabird species to El Ni?o events and other warm episodes on the Wash- ington Coast, 1979-1990. The Condor, 93, 853-858.
[12] Guinet, C., Jouventin, P. and Georges, J.Y. (1994) Long- term population changes of fur seals Arctocephalus gazella and Arctocephalus tropicalis on subantarctic (Crozet) and subtropical (St. Paul and Amsterdam) islands and their possible relationship to El Ni?o Southern Oscillation. Antarctic Science, 6, 473-478.
[13] Limberger, D., Trillmich, F., Kooyma, G. L. and Masluf, P. (1983) Reproductive failure of fur seals in Galapagos and Peru in 1982-1983. Tropical Ocean Atmospheric Newsletter, 21, 16-17.
[14] Jaksic, F.M., Silva, S.I., Meserve, P.L. and Gutierrez, J.R. (1997) A long-term study of vertebrate predator responses to an El Ni?o (ENSO) disturbance in Western South America. Oikos, 78, 341-354. doi:10.2307/3546302
[15] Lima, M. and Jaksic, F.M. (1998) Delayed density-de- pendant and rainfall effects on reproductive parameters of an irruptive rodent population in semiarid Chile. Acta Theriologica, 43, 225-234.
[16] Márquez, C., Wiedenfeld, D.A., Naranjo, S. and Llerena, W. (2008) The 1997-1998 El Ni?o and the Galapagos tortoises Geochelone vandenburghi on alcedo volanco, galapagos. Galapagos Research, 65, 7-10.
[17] Saba, V.S., Santidrián-Tomillo, P. Reina, R.D., Spotila, J.R., Musick, J.A., Evans, D.A. and Paladino, F.V. (2007) The effect of the El Nino Southern Oscillation on the reproductive frequency of eastern Pacific leatherback turtles. Journal of Applied Ecology, 44, 395-404. doi:10.1111/j.1365-2664.2007.01276.x
[18] Beatley, J.C. (1974) Phenological events and their environmental triggers in Mojave Desert ecosystems. Ecology, 55, 856-863. doi:10.2307/1934421
[19] Bowers, J.E. (2005) El Ni?o and displays of spring- flowering annuals in the Mojave and Sonoran deserts. Journal of the Torrey Botanical Society, 132, 38-49. doi:10.3159/1095-5674(2005)132[38:ENADOS]2.0.CO;2
[20] Duda, J.J., Kryzysik, A.J. and Freilich, J.E. (1999) Effects of drought on desert tortoise movement and activity. Journal of Wildlife Management, 63, 1181-1192. doi:10.2307/3802836
[21] Ernst, C.H., Lovich, J.E. (2009) Turtles of the United States and Canada. 2nd Edition, Johns Hopkins University Press, Baltimore.
[22] Medica, P.A., Bury, B.R. and Luckenbach, R.A. (1980) Drinking and construction of water catchments by the desert tortoise, Gopherus agassizii, in the Mojave Desert. Herpetologica, 36, 310-904.
[23] Freilich, J., Burnham, K.P., Collins, C.M. and Garry, C.A. (2000) Factors affecting population assessments of desert tortoises. Conservation Biology, 14, 1479-1489. doi:10.1046/j.1523-1739.2000.98360.x
[24] Henen, B.T. (1997) Seasonal and annual energy budgets of female desert tortoises (Gopherus agassizii). Ecology, 78, 283-296.
[25] Congdon, J.D. (1989) Proximate and evolutionary constraints on energy relations of reptiles. Physiological Zoology, 62, 356-373.
[26] Gibbons, J.W., Greene, J.L. and Congdon, J.D. (1990) Temporal and spatial movement patterns of sliders and other turtles. In: Gibbons, J.W., Ed., Life History and Ecology of the Slider Turtle, Smithsonian Institution Press, Washington, DC, 201-215.
[27] Congdon, J.D., Dunham, A.E. and Tinkle, D.W. (1982) Energy budgets and life histories of reptiles. In: Gans, C., Ed., Biology of the Reptilia, Academic Press, New York, 13, 233-271.
[28] Peterson, C.C. (1996) Anhomeostasis: Seasonal water and solute relations in two populations of the desert tortoise (Gopherus agassizii) during chronic drought. Physiological Zoology, 69, 1324-1358.
[29] Henen B.T., Peterson, C.C., Wallis, I. R., Berry, K.H. and Nagy, K. A. (1998) Effects of climactic variation on field metabolism and water relations of desert tortoises. Oeco- logia, 117, 365-373. doi:10.1007/s004420050669
[30] Changnon, S.A. (2000) El Ni?o 1997-1998, the climate event of the century. Oxford University Press, New York.
[31] Lovich, J.E. and Daniels, R. (2000) Environmental characteristic of desert tortoise (Gopherus agassizii) burrow locations in an altered industrial landscape. Chelonian Conservation and Biology, 3, 714-721.
[32] Lovich, J.E., Medica, P., Avery, H., Meyer, K., Bowser, G. and Brown, A. (1999) Studies of reproductive output of the desert tortoise at Joshua Tree National Park, the Mojave National Preserve, and comparative sites. Park Science, 19, 22-24.
[33] Lovich, J.E., Ennen, J.R., Madrak, S., Meyer, K., Loughran, C., Bjurlin, C., Arundel, T., Turner, W., Jones, C. and Groenendaal, G.M. (2011) Effects of wind energy production on growth, demography and survivorship of a desert tortoise (Gopherus agassizii) population in southern California with comparisons to natural populations. Herpetological Conservation and Biology, 6, 161-174. http://www.herpconbio.org/Volume_6/Issue_2/Lovich_etal_2011.pdf
[34] Boarman, W.I., Goodlett, T., Goodlett, G.C. (1998) Review of radio transmitter attachment techniques for chelonian research and recommendations for improvement. Herpetological Review, 29, 26-33.
[35] Kie, J.G., Baldwin, J.A. and Evans, C.J. (1996) CALHOME: A program for estimating animal homeranges. Wildlife Society Bulletin, 24, 342-344.
[36] Lovich, J.E., Herman, D.W. and Fahey, K.M. (1992) Seasonal activity and movements of bog turtles (Clemmys muhlenbergii) in North Carolina. Copeia, 1992, 1107- 1111. doi:10.2307/1446649
[37] Nieuwolt, P.M. (1996) Movement, activity, and microhabitat selection in the western box turtle, Terrapene ornata luteola, in New Mexico. Herpetologica, 52, 487- 495.
[38] O’Connor, M.P., Zimmerman, L.C., Ruby, D.E., Bulova, S.J. and Spotila, J.R. (1994) Home range size and movements by desert tortoises, Gopherus agassizii, in the eastern Mojave Desert. Herpetological Monographs, 8, 60- 71.
[39] Nagy, K.A., Henen, B.T., Vyas, D.B. and Wallis, I.R. (2002) A condition index for the desert tortoise (Gopherus agassizii). Chelonian Conservation and Biology, 4, 425-429.
[40] Hayes, J.P. and Shonkwiler, J.S. (2001) Morphometric indicators of body condition: worthwhile or wishful think? In: Speakman, J.R., Ed., Body Composition Analysis of Animals: A Handbook of Non-Destructive Methods, Cambridge University Press, Cambridge, 8-38.
[41] Jacobson, E.R., Weinstein, M., Berry, K., Hardenbrook, B., Tomlinson, C. and Freitas, D. (1993) Problems with using weight versus carapace length relationships to assess tortoise health. Veterinary Record, 132, 222-223. doi:10.1136/vr.132.9.222
[42] Longpré, C.I. and Hereford, R. (1998) Climate history of the Mojave Desert Region, 1892-1996, including data from 48 long-term weather stations and an overview of regional climate variation. http://mojave.usgs.gov/climate-history/
[43] Australian Government Bureau of Meteorology. (2011) http://www.bom.gov.au/climate/current/soihtm1.shtml
[44] Oftedal, O. (2002) Nutritional ecology of the desert tortoise in the Mojave and Sonoran Deserts. In: Van Devender, T.R., Ed, The Sonoran Desert Tortoise, Natural History, Biology, and Conservation, University of Arizona Press and The Arizona-Sonora Desert Museum, Tucson, 194-241.
[45] Nagy, K.A. and Medica, P.A. (1986) Physiological ecology of desert tortoises in southern Nevada. Herpetologica, 42, 73-92.
[46] Smith, L.L., Robert, B., Joby, M. and Clement, S. (1999) Home range and microhabitat use in the Angonka (Geochelone yniphora) in Madagascar. Chelonian Conservation and Biology, 3, 393-400.
[47] Peterson, C.C. (1996) Ecological energetics of the desert tortoise (Gopherus agassizii): Effects of rainfall and drought. Ecology, 77, 1831-1844. doi:10.2307/2265787
[48] Henen, B.T. (2002) Energy and water balance, diet, and reproduction of female desert tortoises (Gopherus agassizii). Chelonian Conservation and Biology, 4, 319-329.
[49] Rautenstrauch, K.R., Rager, A.L. and Rakestraw, D.L. (1998) Winter behavior of desert tortoises in southcentral Nevada. Journal of Wildlife Management, 62, 98-104. doi:10.2307/3802267
[50] Nagy, K.A. (1988) Seasonal patterns of water and energy balance in desert vertebrates. Journal of Arid Environments, 14, 210-210.
[51] Morafka, D.J. and Berry, K.B. (2002) Is Gopherus agassizii a desert-adapted tortoise, or an exaptive opportunist? Implications for tortoise conservation. Chelonian Conservation and Biology, 4, 263-287.

Copyright © 2024 by authors and Scientific Research Publishing Inc.

Creative Commons License

This work and the related PDF file are licensed under a Creative Commons Attribution 4.0 International License.