such as "Introduction", "Conclusion"..etc
Thure E. Cerling *, , , George Wittemyer , Henrik B. Rasmussen ¶, Fritz Vollrath ¶, Claire E. Cerling , Todd J. Robinson , and Iain Douglas-Hamilton ||
*Department of Geology and Geophysics, 135 South 1460 East, University of Utah, Salt Lake City, UT 84112; Department of Biology, 257 South 1400 East, University of Utah, Salt Lake City, UT 84112; University of California, Berkeley, CA 94720; ¶Department of Zoology, Oxford University, Oxford OX1 3PS, United Kingdom; and ||Save The Elephants Foundation, Nairobi, Kenya
Contributed by Thure E. Cerling, November 4, 2005
We use chronologies of stable isotopes measured from elephant(Loxodonta africana) hair to determine migration patterns andseasonal diet changes in elephants in and near Samburu NationalReserve in northern Kenya. Stable carbon isotopes record dietchanges, principally enabling differentiation between browseand tropical grasses, which use the C3 and C4 photosyntheticpathways, respectively; stable nitrogen isotopes record regionalpatterns related to aridity, offering insight into localizedranging behavior. Isotopically identified range shifts werecorroborated by global positioning system radio tracking dataof the studied individuals. Comparison of the stable isotoperecord in the hair of one migrant individual with that of aresident population shows important differences in feeding andranging behavior over time. Our analysis indicates that differencesare the result of excursions into mesic environments coupledwith intermittent crop raiding by the migrant individual. Variationin diet, quantified by using stable isotopes, can offer insightinto diet-related wildlife behavior.
13-carbon | 15-nitrogen | chronology | human–elephant conflict
Source: PNAS, January 10, 2006, vol. 103, no. 2, 371-373
The stable isotope ratios of 13C/12C in hair records the dietof mammals (1–4). It is particularly useful in distinguishingdiets of C3 browse versus C4 grass in tropical regions (5–7)because of the large difference in 13C/12C ratios between plantsusing the C3 and C4 photosynthetic pathways, respectively. Intropical regions, the C3 pathway is used primarily by treesand shrubs, whereas plants using the C4 pathway are principallygrasses (8, 9).
Hair is a particularly useful indicator of diet change (3, 4)because the isotope turnover of mammal tissues is high enoughto resolve short-term diet changes. Recent advances in methodology,progressed through the study of large mammals with controlleddiet changes (10, 11), allows detailed reconstruction of thediet history of individual large mammals in wild populations(12, 13).
In this study, we determine the growth rates and stable 13C/12Cand 15N/14N ratios in elephant hair collected between 2001 and2004. We focus on the behavior of a resident population of SamburuNational Reserve, Northern Kenya, for the time period of 2000to 2002. We compare stable isotope results of this residentpopulation with a migrant elephant (B1013) that visited SamburuReserve up to several times each year. Differences in isotoperatios between the resident individuals and the migrant indicatedifferent behaviors, including rapid migration across long distancesby the migrant individual and differences in the fraction C4biomass in the diet. The latter may be related to seasonal cropraiding, which can be quantified by using stable isotope ratios.
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