Reproductive Biology of the White-Crowned Sparrow (Zonotrichia leucophrys pugetensis Grinnell). I. Temporal Organization of Reproductive and Associated Cycles

Abstract

Because of their wide latitudinal distribution, the races of the White-crowned Sparrow (Zonotrichia leucophrys) offer significant opportunities for comparative studies of the adaptive aspects of annual reproductive cycles and the mechanisms by which they are controlled. Of substantial interest among these races is 2. 2. pugetensis, a short-distance migrant whose breeding area (ca. 40-50"N) lies on the Pacific seaboard of North America between that of the highly migratory 2. 1. gambelii (ca. 50-70"N) and that of the sedentary 2. 1. nuttalli (ca. 35-40"N). The shortest migratory route of pugetensis may be considerably less than 500 km; the longest may approach 1900 km. Both the annual photoperiodic environment of pugetensis and its photoperiodic responses differ from those of the two related taxa (see Farner and Lewis 1973; Lewis 1971, 1975). Furthermore, pugetetis and nutialli, which form a cline (Banks 1964; Cortopassi and Mewaldt 1965), typically rear two or more broods per season (Banks 1959; Blanchard 1941), whereas gambelii appears to be obligately single-brooded (King et al. 1966). The present paper is the first of two that deal with the temporal organization of reproduction and its control in 2. 1. pugeteusis. In this paper, the breeding-season phenology and associated physiological and behavioral cycles are described and analyzed as a basis for experimental investigations of the mechanisms that control these functions. STUDY AREAS AND METHODS STUDY AREAS Camano Island (Island County, Washington), the principal study area, is a well-defined physiographic unit of 12,000 ha that lies in the Puget Sound lowland of western Washington, immediately west of the mainland between 48"3' and 48"16' N. It is about 24 km long and 1.5-11 km wide. Z. 1. pugetensis breeds on the island wherever suitable habitat occurs, from sea

Physiological Preparation for Autumnal Migration in White-Crowned Sparrows

“…None of the birds in groups T31 and R70 molted after the transfer to 12L 12D, even though by day 70 seven of 11 had CTW below 50 mg, the threshold assumed to be permissive for molt (Morton et al 1969, Lewis 1975a Body weight. Data are combined for controls and Group T60 prior to day 60 and for groups T31 and R70 prior to day 70, both in Figure 3 and for statistical analysis, since treatments prior to those days were identical (Fig.…”

“…Therefore, these data are pooled in the comparisons that follow (cf. Morton et al 1969, Lewis 1975a, Chilgren 1978.…”

Gonadal and hormonal phenology in free-living male rufous whistlers, Pachycephala rufiventris (Passeriformes : Pachycephalidae)

“…The limited intrapopulational variation of testes size for male whistlers at each breeding stage is also found in migratory species with limited breeding periods (Lewis 1975a(Lewis , 1975bWingfield and Farner 1978a, 1978b, 1979Silverin 1983;Wingfield 1984b;Morton et al 1990). Such testicular synchrony contrasts strongly with the pattern seen in sedentary Australian old endemics such as the bell miner, Manorina melanophrys (Poiani and Fletcher 1994) and white-plumed honeyeater (Astheimer and Buttemer 1999) which have more flexible breeding schedules.…”

“…Another difference between whistlers and passerine migrants in the north temperate zone is their use of breeding territories. White-crowned sparrows use territories for nest sites only, forming loose non-aggressive feeding groups away from nesting areas (Lewis 1975a(Lewis , 1975bFarner 1978a, 1978b). In contrast, rufous whistlers defend all-purpose territories the entire time that they are on the breeding grounds (Bridges 1992;M c Donald 2001).…”

Effect of pinealectomy on gonadal steroid dehydrogenases in the domestic pigeon, Columba livia.

“…Such cyclic changes are marked by significant histophysiological alterations in terms of gametogenesis and steroidogenesis, processes associated with breeding. Amongst birds, histophysiological changes affecting gonads have been recorded mainly in males (Parton & Parton 1922, Marshall 1949, Threadgold 1956, Johnson 1961, Scott & Middleton 1968, Silverin 1973, 1975, Gorman 1974, Lewis 1975a, b, Smith et al 1976, Ambadkar & Chauhan 1976, Mori & George 1978, Kotak 1979. Comparatively fewer studies have been carried out on female gonads (Marshall & Coombs 1957, Chalana & Guraya 1974, Guraya 1976a, b, c, Ambadkar & Chauhan 1977, Kotak 1979.…”