Winter flock structure in the central Monte desert, Argentina

ZARCO, A.; CUETO, V.R.

ARDEA

NEDERLANDSE ORNITHOLOGISCHE UNIE

Año: 2017 vol. 105

0373-2266

Flockingbehavior has been studied for decades around the world, but there is littleknowledge of this subject in desert bird communities. We investigate winterflock structure in open woodlands of the central Monte desert, Argentina, duringtwo consecutive years. Of the twenty-two bird species that were recorded inflocks, most were granivorous. There were differences in flock density betweenyears, probably due to fluctuation in seed abundance. More than half of theobserved flocks were composed of different species (i.e. mixed-species flocks).We detected only two regular species (found in more than 75% of flocks), bothgranivorous birds. Poospiza torquata and Poospiza ornata co-occurred in a higherfrequency than expected by chance, and formed subgroups within flocks. Saltatricula multicolor, Stigmaturabudytoides, Pseudoseisura lophotes andAsthenes baeri were found to form family groups, which may be related todelayed natal dispersal. The observed flocking propensity of granivorous birdsand the small number of species per flock were similar to other desert birdcommunities in the world. We discuss some differences and similarities betweengranivorous and insectivorous flocking patterns, and we propose hypotheses on theplausible causes. Our results provide a basis for a better understanding of theflocking behavior patterns of birds in arid environments.