Trophic niche segregation between two closely related sympatric rock nuthatch (Sitta tephronota and S. neumayer) in Zagrous Mountains

Document Type : Research Paper


1 M.Sc. student of Environmental Science, Faculty of Natural Resources, University of Tehran, Iran

2 Associated professor, Faculty of natural resources, University of Tehran, Iran

3 Assistant professor, Faculty of natural resources, University of Tehran, Iran

4 Assistant professor, Iranian Research Institute of Plant Protection. Insect Taxonomy Research Department


Eastern Rock Nuthatch (Sitta tephronota) and Western Rock Nuthatch (S. neumayer) are two closely related and sympatric species in Iran, which have been known as the classical case of character displacement since 1950. Nevertheless, some questions related their niche partitioning is still unanswered. This study was conducted to determine the diet differentiation, as an important niche dimension, between the two species in their sympatric zone along the Zagros Mountains. The dietary composition of the two species was studied by analyzing stomach contents, using a stereo-microscope. The result showed that the most diet of the two species in spring was insects. Eastern Rock Nuthatch fed predominantly on beetles (Coleoptera), bugs (Hemiptera), and grasshoppers (Orthoptera) whereas Western Rock Nuthatch consumed mostly on bugs (Hemiptera), beetles (Coleoptera), and butterfly’s (Lepidoptera). We used analysis of covariance for finding significant differences in 2 measurement traits in bugs and beetles .Covariance analysis revealed that the relationships between body and prey size differ between the two species only in one measurement (length of head in bugs), as Eastern Rock Nuthatch captured larger prey size. Furthermore our result demonstrated that the niches breathe of these species is rather equal, as well as their niche overlap is high. Overall our results confirmed the importance prey size in trophic niche partitioning and possibility of coexistence for closely related species.


  1. Alatalo, R.V., Moreno, J) 1987 (Body size, interspecific interactions, and use of foraging sitesin tits (Paridae). Ecology 68, 1773-1777.
  2. Andreas, M., Reiter, A., Cepakova, E and Marcel, U) 2013( Body size as an important factor determining trophic niche partitioning in three syntopic rhinolophid bat species. Biologia: 170- 175.
  3. Brown, W. L. and Wilson, E. O (1956) Character displacement. Systematic Zoology. 7, 49-64.
  4. Cornwallis, L. (1975). The Comparative Ecology of Eleven Species of Wheatear (Genus Oenanthe) in SW Iran, University of Oxford.
  5. Freeman, P. W. and C. A. Lemen (2007). Using scissors to quantify hardness of insects: do bats select for size or hardness? Journal of Zoology 271(4): 469-476.
  6. Gause, G .F‏) 1973 (the struggle for existence. Williams and Wilkins, Baltimore, Maryland, USA.350P.
  7. Grant, P. R. (1972). Convergent and divergent character displacement. Biological Journal of the Linnean Society 4(1): 39-68.
  8. Grant, P. R) 1975 (The classical case of character displacement. Evolutionary Biology. 8, 237-337.
  9. Grant, P.R and Grant, B.R) 2002 (Adaptive radiation of Darwin’s finches. American Scientist, 90, 130–139.


  1. Harz, K ) 1975 (Orthopteren Europa’s/the Orthoptera of Europe Vol. 2, Series Entomologica, Springer, 941 p.
  2. Herrel, A., Podos, J., Hubber, S.K and Hendry, A.p) 2005 (Evolution of bite force in Darwin’s finches: a key role for head width. Journal of evolutionary biology.18, 669-675.


  1. Huey, R.B., Pianka, E.R )1981(ecological consequences of foraging mode. Ecology 62, 991-999.
  2. Hutchinson G .E) 1957 (Concluding Remarks. Cold Spring Harb Symposium Quantify Biology, 22, 415–427
  3. .
  4. Hutchinson G. E (1978) an introduction to population ecology. Yale University, New Haven.220 p.


  1. Kaboli, M., Aliabadian, M and Prodon, R (2007) Niche segregation, behavioural differences, and relation to morphology in two Iranian syntopic wheatears: Oenanthe lugens persica and O. oenanthe libanotica. Vie ET Milieu, Life and Sciences, 57: 137-148.
  2. Krebs C.J (1999) Ecological Methodology. Second edition. Addison Wesley Longman, Inc., New York, 620 pp.


  1. Lack, D (1945) The Ecology of Closely Related Species with Special Reference to Cormorant (Phalacrocorax carbo) and Shag (P. aristotelis). Journal of Animal Ecology 14, 12-16.
  2. Lack, D (1947) Darwin’s Finches. Cambridge (United Kingdom): Cambridge.350 p.


  1. Levin’s R (1968) Evolution in Changing Environments: Some Theoretical Explorations. Princeton University Press, Princeton, NJ, USA, 132 pp.


  1. Losos, J. B. (2000). Ecological character displacement and the study of adaptation. Proceedings of the National Academy of Sciences 97(11): 5693-5695.


  1. Lu, X., et al. (2011). "Niche segregation between two alpine rosefinches: to coexist in extreme environments." Evolutionary Biology 38(1): 79-87.


  1. Mayr, Ernst (1970) Populations, Species, and Evolution. Cambridge: Belknap Press of Harvard University Press.532p.
  2. Moermond, T.C (1979) Habitat constraints on the behavior, morphology, and community structure of Anolis lizards. Ecology 60: 152-164.
  3. Pianka, E.R (1975) Niche relations of desert lizards. In: Cody, M., Diamond, J. (Eds.), Ecology and Evolution of Communities. Harvard University Press, Harvard.355 p.
  4. Schluter, D (2000) Ecological character displacement in adaptive radiation. American Naturalist. 156: 4–16.
  5. Schoener, T.W (1965) the evolution of bill size differences among sympatric congeneric species of birds. Evolution 19: 169-213.
  6. Triplehorn, C. A., Johnson, N. F. and Borror, D. J ( 2005) Borror and DeLong's introduction to the study of insects, 7th Ed. Thompson Brooks.University Press. 864 p.
  7. Van der meij, M.A.A. and Bout, R.G (2004) Scaling of jaw muscle size and maximal bite force in finches. The journal of experimental biology.207:2745-2753.
  8. Vaurie, C. (1950) Notes on some Asiatic Nuthatches and Creepers. American Museum Novitiates, 1472: 1-39.
  9. Wang, Z.L., Zhang, D.Y., Wang, G (2005) Doe’s spatial structure facilitate coexistence of identical competitors? Ecological Modell 181:17–23.