High cover of House Wren (Troglodytes aedon) nests increases latency of brood parasitism by Shiny Cowbirds (Molothrus bonariensis)

VANINA D. FIORINI; DIEGO T. TUERO; JUAN C. REBOREDA

EMU

CSIRO PUBLISHING

Año: 2012 vol. 112 p. 55 - 59

0158-4197

Obligate brood parasites must find host nests to lay their eggs and nests built in patches with more cover may have a lower probability of parasitism (nest concealment hypothesis). We experimentally tested this hypothesis by placing nest-boxes used by House Wrens (Troglodytes aedon) in woodland sites with low and high canopy cover and measuring the frequency (proportion of nests parasitized), latency (days elapsed since laying of the first host egg and parasitism) and intensity (number of parasite eggs in parasitized nests) of parasitism by Shiny Cowbird (Molothrus bonariensis). Frequency and intensity of parasitism did not differ between nests-boxes in sites with low or high canopy cover, but latency of parasitism was shorter in sites with low cover than in those with high cover. Shorter latencies of parasitism increase the reproductive success of parasites and decrease that of hosts. Because woodland degradation is associated with lower canopy cover, host species nesting in degraded woodlands may suffer higher costs of parasitism than those nesting in conserved woodlands.