Winter flock structure in the central Monte desert, Argentina

A ZARCO; CUETO VR

ARDEA

NEDERLANDSE ORNITHOLOGISCHE UNIE

Año: 2017

0373-2266

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