Breeding Ecology of House Sparrows: Spatial Variation

Studies of the introducedHouse Sparrow (Passer domesticus) have provided unique insight into the nature and rate of phenotypic change of an avian species in novel environments.Several investigators (e.g.Calhoun 1947, Johnston and Selander 1973a, b) have documented rapid geographic differentiation in body size since the species was first introduced to North America a little over a century ago.The geographic patterns in body size and dimensions, and those in plumage characters (Johnston and Selander 1964)) agree with Bergmann' s, Allen' s and Gloger' s ecogeographic rules, respectively.Geographic trends in thermal tolerances (Hudson and Kimzey 1966)) lipid deposition (Blem 1973)) insulation and metabolism (Blem 1974, Kendeigh and Blem 1974, Kendeigh 1976) have been documented also.Anderson ( 1973 : 44) noted that clutch size of House Sparrows is positively correlated with latitude in North America.Studies of breeding ecology at several localities in North America (Weaver 1939, 1942, 1943, North 1968, 1973a, Will 1969, 1973, Anderson 1973, Mitchell et al. 1973, Sappington 1975, present study) allow documentation of geographic differentiation in breeding phenology and reproductive output.In this paper, differences between two localities, Calgary, Alberta and Lawrence, Kansas, will be examined in detail.North American House Sparrows "have descended almost exclusively from English inocula" (Johnston and Selander 1973a:383, also see Barrows 1889, Summers-Smith 1963).Studies of breeding ecology in England (Summers-smith 1963, See1 1968a, b, 1970, Dawson 1972) together with those in North America permit comparison of reproductive ecology of ancestral and descendent populations.Several studies in temperate regions (e.g.Nice 1937, Kendeigh 1963) have suggested that both photoperiod and temperature are proximate factors which cue or control breeding phenology.In contrast, Jones and Ward (1976:573) suggested that breeding of the Red-billed Quelea (Quelea quelea) is controlled simply by body condition of adults and that no environmental cues are necessary to trigger breeding at the appropriate time of year.I will evaluate the role of photoperiod and temperature in timing the initiation of House Sparrow breeding seasons.Numerous factors have been implicated in variation in reproductive ecology, particularly clutch size, of birds (e.g.reviews by Klomp 1970, Cody 1971) .Studies of House Sparrow reproduction have revealed significant microgeographic variation.Reproduction begins earlier if the nest is inside, rather than outside, a building (Will 1969).Reproductive output is inversely related to distance between the nest and feeding sites (Dawson 1972).I have separated variation between localities into study site and nest site effects, gaining insight into the contribution of microhabitat effects to overall variation in reproductive ecology. STUDY AREAS AND METHODSThe study sites were nine farms located about 8 km NE of Lawrence, Kansas, and six farms, a granary complex and a rural residence near Comich, Alberta, 5 km E of Calgary (Fig. 1).Study sites are coded with a letter corresponding to the first letter of the locality and a number corresponding to the site numbers of Figure 1.Thus C2 denotes site 2 in Calgary.Cattle were raised on all of the farms.Principal crops on the Calgary farms were oats ( Auena satioa) and barley ( Hordeurn spp.), while those at Lawrence were corn (Zea mays), wheat ( Tfiticum spp.), soybeans (Glycine so@), and milo (Sorghum dgare).Feed grain was stored at or near all study sites, and generally several thousand bushels of seed were stored at each Calgary site.