CONICET | Buscador de Institutos y Recursos Humanos

Participation inmixed species flocks may help increase feeding efficiency (number ofattacks/time) of birds by finding more places to feed, knowing recentlydepleted areas, benefiting from flushing insects, and increasing predationavoidance. Birds in yungas foothill live in a fragmented landscape. Forestfragments could contain limited food in comparison to continuous forest. Wecompared feeding efficiency and search rate (number of search behaviors/time)of three species in foothill forest, Salta, Argentina: Parula pitiayumi,Thraupis sayaca and Arremon flavirostris. Five surveys were conducted through 7months recording foraging behavior. Ratios of search and attack trough timewere compared in two social situations (inside/outside mixed-species flocks)and at two landscape configurations (forest fragment/continuous forest). Parulapitiayumi and Thraupis sayaca increased their feeding efficiency whenparticipating in mixed flocks inside forest fragments (Kruskal Wallis;P-values<.05, n=71 and n=28 respectively), while Arremon flavirostris didnot show differences (P=0.32, n=41). Thraupis sayaca increased its search rate(p=0.0484) outside flocks in continuous forest, while no differences weredetected in P. pitiayumi and A. flavirostris. These results suggest thatflocking might report more benefits in forest fragments than in continuousforests in our study sites. Surveys measuring food availability and predatorabundance are being conducted and should provide critical data to explain theobserved patterns.