Conspecific nest aggression of the pacific wren on vancouver Island, British Columbia

Abstract

Five of the ten wren species in North America are known to destroy nests of conspecifics. These include the Cactus Wren (Campylorhynchus brunneicapillus), Bewick's Wren (Thryomanes bewickii), Sedge Wren (Cistothorus platensis), Marsh Wren (Cistothorus palustris), and House Wren (Troglodytes aedon). However, none of the Winter Wren complex, recently split as the Winter Wren (Troglodytes hiemalis), Pacific Wren (T. pacificus), and Eurasian Wren (T. troglodytes), have been documented to do so in experiments or by observation of natural behavior. Here we present a detailed chronology of a nesting of the Pacific Wren-the first report of conspecific nest aggression in the Winter Wren complex. On 15 May 2011, in Victoria, British Columbia, Canada, a Pacific Wren approached another's nest under video surveillance and removed two 9-day-old chicks. The nonparental adult returned to the nest, apparently attempting to kill and/or and remove the remaining two chicks, several times over 4.75 hours but was not successful. Although our findings are limited to a single event, they are consistent with those of other wrens.