Keywords
Pampean agroecosystem
raptors
seasonality
Abstract
We counted raptors in two transects (A and B) in an agroecosystem located in south-eastern Buenos Aires Province, in order to quantify habitat use. We recorded six species of diurnal raptors: Elanus leucurus, Circus cinereus, Circus buffoni, Milvago chimango, Falco femoralis and Falco sparverius. In the transect A we observed all six species. Most of them used harvested wheat fields in a greater or similar proportion respect to their availability during summer and autumn. Elanus leucurus used pastures in a greater or similar proportion respect to their availability during summer, autumn and winter, whereas Milvago chimango used them during summer and autumn. In transect B we recorded only Elanus leucurus, Milvago chimango and Falco sparverius while hunting. Elanus leucurus hunted in harvested soybean fields in a greater or similar proportion respect to their availability during autumn, and hunted heavily in pastures. Falco sparverius used mountain grassland habitats. In both transects, only Milvago chimango hunted in plowed fields, and most species avoided or showed little use of crop fields. In transect A, raptors hunted more frequently during autumn; in transect B they hunted more frequently during summer. Milvago chimango hunted more frequently during winter in both transects. The selection of hunting habitat that we observed in this study might be more influenced by prey accessibility than by prey abundance.
References
BABCOCK K (1995) Home range and habitat use ofbreeding Swainson¥s Hawk in the Sacramento Val-ley of California. Journal of Raptor Research 29:193ñ197
BAKER J Y BROOKS R (1981) Distribution patterns ofraptors in relation to density of meadow voles. Con-dor 83:42ñ47
BECHARD MJ (1982) Effect of vegetative cover on for-aging site selection by Swainson¥s Hawk. Condor84:153ñ159
BERRY M, BOCK C Y HAIRE S (1998) Abundance of di-urnal raptors on open space grasslands in an ur-banized landscape. Condor 100:601ñ608
BOSAKOWSKI T Y SMITH D (1997) Distribution and spe-cies richness of a forest raptor community in rela-tion to urbanization. Journal of Raptor Research 31:26ñ33
COLLOPY MW Y BILDSTEIN KL (1987) Foraging behav-ior of Northern Harriers wintering in southeasternsalt and freshwater marshes. Auk 104:11ñ16
COMPARATORE VM, MARTÕNEZ MM, VASSALLO AI, BARGM Y ISACCH JP (1996) Abundancia y relaciones conel h·bitat de aves y mamÌferos en pastizales dePaspalum quadrifarium (Paja colorada) manejados confuego (Provincia de Buenos Aires, Argentina).Interciencia 21:228ñ237
DON¡ZAR JA, NEGRO JJ Y HIRALDO F (1993) Foraginghabitat selection, land-use changes and populationdecline in the Lesser Kestrel Falco naumanni. Journalof Applied Ecology 30:515ñ522
ESTEP JA (1989) Biology, movements and habitat relation-ships of the Swainson¥s hawk in the Central Valley ofCalifornia, 1986ñ87. Nongame Bird and MammalSec. Report, Calif. Dept. Fish and Game, Sacramento
GALBRAITH H (1988) Effects of agriculture on thebreeding ecology of lapwings Vanellus vanellus. Jour-nal of Applied Ecology 25:487ñ503
HAYES FE (1991) Raptor densities along the Paraguayriver: seasonal, geographical and time of day varia-tion. Journal of Raptor Research 25:101ñ108
DEL HOYO J, ELLIOT A Y SARGATAL J (1994) Handbook ofthe birds of the world. Volume 2. New World vultures toguineafowl. Lynx Edicions, Barcelona
KOTLIAR NB Y WIENS JA (1990) Multiple scales ofpatchiness and patch structure: a hierarchical frame-work for the study of heterogeneity. Oikos 59: 253ñ260
LEVEAU LM, LEVEAU CM Y PARDI—AS UFJ (en prensa)Dieta del Milano Blanco (Elanus leucurus) en Argen-tina. OrnitologÌa Neotropical
MILLS JN, ELLIS BA, MCKEE KT, MAIZTEGUI JI Y CHILDSJE (1991) Habitat associations and relative densitiesof rodent populations in cultivated areas of centralArgentina. Journal of Mammalogy 72:470ñ479
NEWTON I (1979) Population ecology of raptors. T. & A.D. Poyser, Londres
PRESTON C (1990) Distribution of raptor foraging inrelation to prey biomass and habitat structure. Con-dor 92:107ñ112
ROBINSON RA, WILSON JD Y CRICK HQP (2001) Theimportance of arable habitat for farmland birds ingrassland landscapes. Journal of Applied Ecology38:1059ñ1069
ROBINSON SK (1994) Habitat selection and foragingecology of raptors in Amazonian Per ̇. Biotropica26:443ñ458
ROTENBERRY JT Y KNICK ST (1999) Multiscale habi-tat associations of the sage sparrow: implicationsfor conservation biology. Studies in Avian Biology19:95ñ103
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