Skip to main content Accessibility help

Distributional patterns of raptors along altitudinal gradients in the northern Andes and effects of forest fragmentation

  • Jean-Marc Thiollay (a1)


A survey of the diurnal raptor community (46 resident species) at five altitudinal levels from 100 to 4600 m was made in Venezuela using 106 1-km2 sample quadrats and then compared with similar censuses (211 plots) in southwestern Colombia and eastern Ecuador. Six habitat types were defined and habitat preferences were measured from every encountered birds and from the association between individual abundances and the coverage of habitat types on plots. The overall species richness steeply declined with elevation in all three countries. The raptor community consisted mostly of tropical species that rapidly decreased in both abundance and frequency of occurrence with elevation. A small set of subtropical-temperate forest specialists partly replaced them at mid-elevation and only two species occurred in the paramo of Venezuela, against 5–7 in the other countries. Although originally the gradients were probably almost completely covered with forest, a large part of the raptor community is now composed of grassland species, three of them extending from the lowlands to the tree line. The relative impoverishment of the Venezuelan community, especially at upper levels, is attributed to a peninsular effect at the narrow extreme northern tip of the Andes and perhaps also to former forest fragmentation. Within some species, different subspecies had discrete altitudinal distributions and interspecific competition may explain differences in the range extension of some species between countries. Today, however, accelerating deforestation may result in a severe decline of forest-interior species and a probable reduction in the altitudinal range of at least some of them. Species naturally associated with forest gaps or edges usually tolerate a high degree of forest fragmentation and degradation but only one of them may become abundant in heavily human-altered woodlands. Few grassland specialists have become more widely distributed in the increasingly deforested landscapes.



Hide All
Able, K. P. & Noon, B. R. 1976. Avian community structure along elevational gradients in the north eastern United States. Oecologia 26:275294.
Alvarez Del Real, M. E. (ed.) 1983. Atlas of Venezuela. Distribucion Escolar, Caracas, 320 pp.
Blake, E. R. 1977. Manual of Neotropical birds. University of Chicago Press, Chicago, 674 pp.
Butler, T. Y. 1979. The birds of Ecuador and the Galapagos archipelago. Ramphastos Agency, Portsmouth, N. H.68 pp.
Chapman, F. M. 1917. The distribution of bird life in Colombia. Bulletin of the American Museum of Natural History 36:1169.
Chapman, F. M. 1926. The distribution of bird life in Ecuador. A contribution to a study of the origin of andean bird life. Bulletin of the American Museum of Natural History 55:1784.
Collar, N. J., Gonzaga, L. P., Krabbe, N., Madrononieto, A., Naranjo, L. G., IIParker, T. A. & Wege, D. C. 1992. Threatened birds of the Americas. ICBP/IUCN Red Data Book. Smithsonian Institution Press. 1150 pp.
Fjeldsa, J. & Krabbe, N. 1990. Birds of the High Andes. Apollo Books, Svendborg, Denmark. 876 pp.
Fuller, M. R. & Mosher, J. A. 1987. Raptor survey techniques. Pp. 3766 in Pendleton, B. A. Giron, Millsap, B. A., Kline, K. W. and Bird, D. M. (eds) Raptor management techniques manual. National Wildlife Federation, Washington D.C.420 pp.
Graham, G. L. 1990. Bats versus birds: comparisons among Peruvian flying vertebrate faunas along an elevational gradient. Journal of Biogeography 17:657668.
Haffer, J. 1974. Avian speciation in tropical South America. Publications Nuttall Ornithological Club 14. Cambridge, Mass.390 pp.
Hanski, I. 1978. Some comments on the measurement of niche metrics. Ecology 59:168174.
Hilty, S. L. and Brown, W. L. 1986. A guide to the birds of Colombia. Princeton University Press, Princeton, New Jersey. 836 pp.
Holdridge, L. R. 1967. Life zone ecology. Tropical Science Center, San Jose, Costa Rica.
Jacobs, J. 1974. Quantitative measurement of food selection: a modification of the forage ratio and Ivlevs' electivity index. Oecologia 14:413417.
Levins, R. 1968. Evolution in changing environments: some theoretical explorations. Princeton University Press, Princeton, New Jersey.
Loiselle, B. A. & Blake, J. G. 1991. Temporal variation in birds and fruit along an elevational gradient in Costa Rica. Ecology 72:180193.
Meyer De Schauensee, R. & Phelps, W. H. 1978. A guide to the birds of Venezuela. Princeton University Press, Princeton, New Jersey. 424 pp.
Monasterio, M. (ed.) 1980. Estudios ecologicos en los Paramos Andinos. Ediciones Universidad de los Andes, Merida. 312 pp.
Navarro, A. G. S. 1992. Altitudinal distribution of birds in the Sierra Madre del Sur, Guerrero, Mexico. Condor 94:2939.
Neu, L. W., Byers, C. R. & Peek, J. M. 1974. A technique for analysis of utilization-availability data. Journal of Wildlife Management 38:541545.
Noon, B. R. 1981. The distribution of an avian guild along a temperate elevational gradient: the importance and expression of competition. Ecological Monographs 51:105124.
Patterson, B. D. & Atmar, W. 1986. Nested subsets and the structure of insular mammalian faunas and archipelagoes. Biological Journal of Linnean Society 28:6582.
Peck, S. B. & Kukalova-Peck, J. 1980. A guide to some natural History field localities in Ecuador. Studies on Neotropical Fauna and Environment 15:3555.
Remsen, J. V. 1985. Community organization and ecology of birds of high elevation humid forest of the Bolivian Andes. Pp. 733756 in Buckley, P. A. et al. (ed.). Neotropical ornithology. American Ornithologists' Union.
Roughgarden, J. 1989. The structure and assembly of communities. Pp. 203226 in Roughgarden, et al. (eds), Perspectives in ecological theory. Princeton University Press, Princeton, New Jersey.
Sarmiento, G., Monasterio, M., Azocar, A., Castellano, E. & Silva, J. 1971. Estudio integral de la Cuenca de los Rios Chama y Capazon. Vegetation natural. Institute de Geographia y Conservation de Recursos Naturales, Universidad de los Andes, departamento de Biologia, Merida. 65 pp.
Stevens, G. C. 1992. The elevational gradient in altitudinal range: an extension of Rapoport's latitudinal rule to altitude. American Naturalist 140:893911.
Terborgh, J. 1971. Distribution on environmental gradients: theory and a preliminary interpretation of distributional patterns in the avifauna of the Cordillera Vilcabamba, Peru. Ecology 52:2340.
Terborgh, J. 1977. Bird species diversity on an Andean elevational gradient. Ecology 58:10071019.
Terborgh, J. 1985. The role of ecotones in the distribution of Andean birds. Ecology 66:12371246.
Terborgh, J. & Weske, J. S. 1975. The role of competition in the distribution of Andean birds. Ecology 56:562576.
Thiollay, J. M. 1989. Area requirements for the conservation of rain forest raptors and game birds in French Guiana. Conservation Biology 3:128137.
Thiollay, J. M. 1991. Altitudinal distribution and conservation of raptors in south western Colombia. Journal of Raptor Research 25:18.
Thiollay, J. M. 1993. Response of a raptor community to shrinking area and degradation of tropical rain forest in the south western Ghâts (India). Ecography 16:91110.
Vuilleumier, F. 1970. Insular biogeography in continental regions. I. The northern Andes of South America. American Naturalist 104:377388.
Vuilleumier, F. 1984. Zoogeography of Andean birds: two major barriers, and speciation and taxonomy of the Diglossa carbonaria superspecies. National Geographic Society Research Report 16:713731.
Vuilleumier, F. 1986. Origins of the tropical avifaunas of the high Andes. Pp. 586622 in Vuilleumier, F. & Monasterio, M. (eds), High altitude tropical biography. Oxford University Press, New York. 649 pp.
Vuilleumier, F. & Ewert, D. N. 1978. The distribution of birds in Venezuelan paramos. Bulletin of the American Museum of Natural History 162:4990.
Vuilleumier, F. & Monasterio, M. (eds) 1986. High altitude tropical biogeography. Oxford University Press, New York. 649 pp.


Distributional patterns of raptors along altitudinal gradients in the northern Andes and effects of forest fragmentation

  • Jean-Marc Thiollay (a1)


Full text views

Total number of HTML views: 0
Total number of PDF views: 0 *
Loading metrics...

Abstract views

Total abstract views: 0 *
Loading metrics...

* Views captured on Cambridge Core between <date>. This data will be updated every 24 hours.

Usage data cannot currently be displayed