a1 Laboratoire d'Ecologie, C.N.R.S. – URA 258, Université Pierre et Marie Curie, 7 Quai St Bernard, 75252 Paris, France
a2 Department of Zoology, University of Wisconsin, Madison, Wisconsin 53706, USA
Parasites are generally found aggregated among hosts. In this paper we propose a method for measuring aggregation at different scales in the host population. We use the method to characterize the pattern of aggregation of the tick Ixodes uriae on chicks of its seabird host, the Kittiwake Rissa tridactyla. We found evidence of aggregation at the among-nest scale, but not among chicks within nests. This shows that the processes leading to aggregation occur at a higher scale than the nest. The methods we develop provide a way to compare parasite aggregation at different scales in a quantitative fashion and can be applied in a large number of epidemiological studies.
(Received July 26 1995)
(Revised October 06 1995)
(Accepted January 04 1996)
c1 Corresponding author: National Biological Service, Patuxent Environmental Science Center, 11510 American Holly Drive, Laurel, Maryland 20708, USA.
p1 Present address: National Biological Service, Patuxent Environmental Science Center, Laurel, Maryland 20708, USA.