Cueto V.R.,University of Buenos Aires |
Milesi F.A.,University of Buenos Aires |
Marone L.,Desert Community Ecology Research Team Ecodes |
Marone L.,University of Santiago de Chile
Journal of Avian Biology | Year: 2013
We assessed experimentally if the main granivorous bird species that feed on the ground in the central Monte desert are able to detect and consume seeds buried in the soil or trapped within litter. Understanding seed vulnerability to birds allows 1) a better understanding of how seed abundance translates into seed availability, a necessary step to assess seed limitation scenarios, and 2) whether birds alter the distribution of soil seeds through their consumption. Rufous-collared sparrows found and consumed high proportions of buried seeds, though less seeds were eaten at increasing depths. In contrast, many-colored chaco-finches, common diuca-finches and cinnamon warbling-finches did not find buried seeds. All bird species fed on every substrate offered but, as a whole, birds reduced by 50% their seed consumption in Prosopis litter, and by 30% in Larrea litter, compared to consumption in bare soil. This effect was less notable for rufous-collared sparrows, whose 'double scratch' foraging method would contribute to its great diet breath and abundance in the Monte desert. As birds do not reach a fraction of seeds buried and trapped by litter, seeds readily available for them may be scarcer than previously estimated through soil seed bank studies. Furthermore, since the four bird species detect and consume seeds from littered microhabitats, seed consumption by them surely affects the seasonal dynamics of the soil seed bank in all microhabitat types of the Monte desert. © 2013 The Author. Journal of Avian Biology © 2013 Nordic Society Oikos.
Lacoretz M.V.,Desert Community Ecology Research Team Ecodes |
Sagario M.C.,Desert Community Ecology Research Team Ecodes |
Cueto V.R.,Desert Community Ecology Research Team Ecodes
Emu | Year: 2012
Habitat selection by birds is the result of hierarchical decisions that may be based on different cues at different spatial scales. However, studies rarely assess patterns of selection at multiple scales simultaneously in order to understand the processes leading to the observed selection patterns. In the central Monte Desert, at the habitat scale, the density of Pale-breasted Spinetails (Synallaxis albescens) during the breeding season is higher in mesquite (Prosopis flexuosa) open woodlands than in creosote (Larrea cuneifolia) shrublands. Causes of this pattern may be revealed by exploring how Pale-breasted Spinetails use space at different scales. At the microhabitat scale, birds selected the highest mesquite trees and avoided creosotes for territorial displays. However, they did not establish territories in patches where mesquite trees were taller than expected. Moreover, at the mesohabitat scale, the cover of mesquite trees within territories was greater than expected only in the plot with a lower cover of mesquite trees. Therefore, the pattern of vegetation selection at the habitat scale matched that at the microhabitat scale, but not completely at the mesohabitat scale. Our study provides insight about the mechanisms driving patterns of habitat selection by Pale-breasted Spinetails in the central Monte Desert. It also highlights the significance of considering vegetation structure and composition at multiple spatial scales when evaluating how birds select where to establish their territories. © 2012 BirdLife Australia.