Dispersion patterns in a Great Bustard (Otis tarda) population in northwestern Spain

Full article

Published:

Volume 38(2), December 1991. Pages 265-276.

Language:

Spanish

Original title:

Relaciones espaciales en una población de Avutarda (Otis tarda) del noroeste de España

Keywords:

flock composition, flock dispersion, flock size, individual dispersion, Northwest Spain, Otis tarda, spatial and temporal variation.

Abstract:

We analyzed the spatial and temporal variation and the variation according to flock size and flock composition of individual dispersion and flock dispersion, in a Great bustard (Otis tarda) population in Northwest Spain. Individual dispersion differs significantly according to size and flock composition, with an inverse relation between mean flock size and mean individual distance, which is maximal in familiar groups. The greatest distances are observed in April and during summer, and the smallest in winter. The distance is minimal at midday and maximal in early morning and again in early evening. Individual spacing also differs according to the type of land use, with minima in edge and maxima in pasture. Flock dispersion increases significantly as flock size does, being minimal in the families and maximal in both male and mixed flocks. Distance to nearest flock is maximal in winter and minimal in July. The daily flock dispersion presents minima during early morning and late afternoon, and maxima at midday. Flock dispersion is minimal in pasture and maximal in edge.