Variation in parental care in the spectacled tyrant Hymenops perspicillatus is associated with increased nest predation in grassland fragments

PRETELLI MATIAS GUILLERMO; JUAN PABLO ISACCH; DANIEL AUGUSTO CARDONI

Journal of Ornithology

Springer Berlin Heidelberg

Año: 2016 vol. 157 p. 451 - 460

2193-7192

Predation risk on birds is often an importantsource of natural selection that shapes parental care andmay promote behavioral changes. Parents can often estimatecertain risks and adjust their behavior to reduce thelikelihood of nest predation. The fragmentation of habitatsis one of the main consequences of loss of habitats, and ingeneral, for birds breeding in smaller patches, their dailynest-survival rate is lower due to increased nest predation.Since nest survival is an estimate of predation risk in theenvironment, we evaluated the daily survival rate (DSR)for nests of spectacled tyrants (Hymenops perspicillatus)and parental care behavior on fragmented and unfragmentedgrasslands. We conducted nest searching andmonitoring during the 2012?2013 breeding season in smallpatches and in a continuous patch of grassland. In addition,parental activity was recorded using video monitoring. Wefound a lower DSR for the spectacled tyrant in fragmentedgrasslands, associated with increased nest predation risk;females showed a variation in parental care. This variationwas evidenced by larger incubation bouts and lower visitationrate during the incubation period, and by a lowerfood delivery rate to nestlings, compensated by larger preysizes. The results show that fragmentation not only reducesthe fitness of individuals and impacts adversely on population,but individuals are also subjected to a strongselection pressure, and their reproductive success maydepend to some extent on the ability of parents to estimateat least certain predation risk and adjust their behavior inthis regard.