Introduction

An affinity for open, shrubby wood-lands, mimicked so well by small town and suburban backyards and city parks, a preference for human-made “bird houses,” and a very loquacious nature all combine to make the House Wren one of the best-known songbirds in North America. House Wrens also nest readily in small woodlots and at forest edges and thus have no doubt benefited greatly from the fragmenting of large forests that has occurred across much of North America since the arrival of Europeans. Indeed, the clearing of forests for farms and towns seems to have allowed this species to expand its breeding range substantially, especially in the southeastern United States.

House Wrens are arguably the most thoroughly studied passerine in North America, in part because they so readily use human-made nest sites, and because they are ubiquitous, relatively abundant across most of their range, and tolerant of human activity. Research on this species began in earnest with the work of S. Charles Kendeigh, who studied the physiology and behavior of an Ohio population from 1921 to 1939. Building on Kendeigh’s initial studies, investigators have conducted extensive research during the last 20 years on this species’ breeding energetics, mating system, habitat and nest-site selection, natal and breeding dispersal, territorial behavior, ecological and evolutionary determinants of clutch size, and relationships with ectoparasites. The popularity of House Wrens as a research subject has not waned; at least half a dozen studies of this species are usually in progress at any one time.

House Wrens occupy the broadest latitudinal range of any native passerine in the New World, breeding from across most of Canada down to the southernmost part of South America, and into the West Indies. Within this range, taxonomic authorities recognize several subspecies groups, some of which were previously treated as separate species. This account discusses primarily the biology of the northernmost group, referred to as the Northern House Wren (aedon group), breeding across southern Canada and throughout much of the United States. Discussed only briefly is the Brown-throated Wren (brunneicollis group) of montane oak-pine (Quercus-Pinus) forests in Mexico which is largely unstudied and of still uncertain affinities to populations that appear intermediate to the Northern House Wren in southeastern Arizona; the Southern House Wren (musculus group), occupying southern Mexico and points south; the Antillean House Wren (martinicensis group) of the Lesser Antilles; and the Cozumel Wren (beani group), resident on Cozumel I. off the Yucatan Peninsula, Mexico. For additional information on the biology of the Southern House Wren, readers can consult Haverschmidt 1952, Skutch 1953, Freed 1987, Young 1996, and references therein.