Determining Breeding Areas and Migration Routes of Coastal Northwest Sooty Fox Sparrows (Passerella iliaca unalaschcensis ) Over-Wintering on Vancouver Island using Geolocators Summary The phylogeography of the Fox Sparrow ( Passerella iliaca ) has been much debated, but birds breeding along the west coast of North America are generally considered to be a separate species ( Passerella iliaca unalaschecensis ) based on mitochondrial DNA. Using plumage characteristics, a further seven sub- species have been identified within this group. These subspecies, and their migration patterns, have become an emblematic example of leap-frog migration, based upon the early work of Swarth (1920). However, more recently, these connectivity patterns have been called into question, partly based on the relative difficulty in accurately distinguishing plumages and subspecies in the field. Light-level geolcators are now small enough to be carried by <50 g songbirds and can reveal remarkable new insights into migration patterns and behaviour. Using geolocators, we will track a population of Fox Sparrows overwintering on southern Vancouver Island to their breeding areas. The objectives of this study are two-fold: 1) Based on leapfrog patterns identified by Swarth (1920) we will use direct-tracking methods to test the hypothesis that birds overwintering on Vancouver Island breed on the island and do not mix with birds along the northwest coast (i.e. strong connectivity) and 2) Identify connections between overwintering and breeding areas that are important to conservation and management of Fox Sparrow populations. Personnel • Project Leader: Michael Simmons, Rocky Point Bird Observatory (RPBO) • Migration Research Advisor: Dr. Bridget Stutchbury, York University • Science and Geolocator Technical Advisor and Data Analyst: Dr. Kevin Fraser, York University • Vancouver Island Science Advisors: Bruce Cousens, M.Sc., R.P.Bio., BC Purple Martin Stewardship & Recovery Program, and RPBO, and Dr. Jonathan Moran, Royal Roads University and RPBO • Field Leader: Ann Nightingale, RPBO 1 Introduction and Background The Fox Sparrow ( Passerella iliaca ) is divided into four groups on the basis of mitochondrial DNA and corresponding plumage characteristics (Zink, 1994). Only one of these groups is found in coastal BC, i.e., the Coastal Northwest Sooty Fox Sparrow ( P. i. unalaschcensis ); within this group seven sub-species are recognized (Pyle, 1997). Breeding ranges and southward migration to over-wintering areas have been identified for these sub-species (Swarth, 1920; Figure 1). Breeding areas are shown with solid blue lines. Wintering areas are surrounded with dashed lines. Presumed migration routes link breeding and wintering areas. P.i. fuliginosa winters within the breeding area Figure 1: Map from Swarth, 1920 Leap-frog migration in the Sooty Fox Sparrow was first described by Swarth (1920), and the concept was refined by Bell (1997; Figure 1). Simply put, the most northerly breeders winter the furthest south. The most southerly breeder ( P. i. fuliginosa ) breeds in SE Alaska, on the west coast of Vancouver Island and in immediately adjacent areas of Washington State. The map of leap-frog migration created by Swarth (1920) shows six sub-species and their migration patterns, Figure 1, above. According to Bell (1997): “The status of this distribution as the exemplar of leap-frog migration patterns is to some extent unfortunate because, although there are elements of a leap-frog pattern in this distribution, a number of factors confound both the leap-frog pattern and its interpretation. For instance, the breeding areas of populations which winter in southern California are only marginally the most distant from the wintering area, a fact which is not immediately obvious from the illustration used in Swarth's (1920) paper, and frequently reproduced elsewhere (e.g., Faaborg 1988, Welty and Baptista 1988), because of the orthographic projection used. One of these populations, P. i. unalaschcensis , has a breeding distribution with a latitudinal range similar to that of P. i. townsendi which winters much further north, and P. i. insularis and most P. i. unalaschcensis breed to the south of P. i. annectens which also has a relatively northern wintering range. 2 Ignoring the three western subspecies, a leap-frog pattern can be discerned among P. i. annectens , P. i. townsendi and P. i. fuliginosa … “ Bent (1968) describes the difficulty of field identification of the sub-species: Adjoining races inter-grade wherever their ranges meet, and the differences between some forms are so slight that the practicality of such fine splitting is sometimes questioned. For instance George Willett (1933) states his "personal feeling is that we are attempting to recognize too many races of Passerella and that the situation might be greatly clarified by uniting some of the most closely allied forms." He suggests that uniting insularis and sinuosa with unaIaschcensis , "would greatly simplify the classification of the group." Gabrielson and Lincoln (1959) state: "It is not possible, however, to accurately identify [the Alaskan subspecies] in the field except as Fox Sparrows. All are large sparrows with dark brown or grayish brown backs with very heavily streaked under-parts.” Over-wintering sub-species of Coastal Northwest Sooty Fox Sparrows on Southern Vancouver Island may include the following: • P.i. unalaschcensis ; • P.i. sinuosa ; • P.i. townsendii ; and • P.i. fuliginosa . Linsdale (1928) highlighted variations in the skeletons of these sub-species that appear to be related to migration: “In every case the samples with large bones in the wings and pectoral girdle belong to races which have long migration routes and the samples with those bones weakly developed belong to relatively sedentary races.” Differentiation of the sub-species is difficult in the field and in the hand. Wintering birds in southern Vancouver Island have not been differentiated by RPBO and it is assumed that most of these birds are P. i. fuliginosa . We do know that almost all Fox Sparrows observed in southern Vancouver Island are of the Coastal Northwest Sooty group. A very few birds are of the interior Slate-coloured group and very rarely birds of the Red group are seen (Cruikshank, personal communication). For this project we will only use birds of the “Sooty” group. Fox Sparrows can be found throughout the Greater Victoria area during the winter months and are common in backyards and on the ground near feeding stations. The highest density of Fox Sparrows recorded during a Christmas Bird Count in the Victoria count circle was 923, and in 2011, the total was 899 (Christmas Bird Counts, Victoria Natural History Society, BC). The closest known breeding area is about 60km from Victoria, near Shirley, west of Sooke. (BC Breeding Bird Atlas, 2008-2012). These observations suggest that at the very least, there is a considerable short-distance migration. 3 RPBO fall migration records show that there have been 59 returns of Fox Sparrows in later years since 1994. Of the returning birds, 27% return for two years, 15% return for three years, and one bird has returned and been recaptured for five successive years. In one remarkable year (1998), 16 of the Fox Sparrows banded returned in subsequent years, including the five-year veteran. Even though the fall migration monitoring season at Rocky Point ends relatively early for returning Fox Sparrows, we believe that these birds are returning to use Rocky Point as their wintering area. Evidence for this assertion is that once Fox Sparrows return, the individual birds are often recaptured several times. This leads us to believe that they are winter residents rather than transient migrants. Fox Sparrows as Candidates for Geolocator Use Southern Vancouver Island is a wintering area for a great number of species that breed elsewhere. However, the routes by which this concentration of winter species disburse to breeding areas to the north and east, remain unknown. Significant concentrations of the Coastal Northwest Sooty Fox Sparrow winter in southern Vancouver Island and this typically west coast species is known to breed over a wide coastal range to the north (Figure 1). There is no known nesting in the immediate vicinity of Victoria, but breeding has been reported in other areas of Vancouver Island. The introduction of relatively low cost geolocators that can be attached safely to smaller birds provides the first opportunity to identify breeding locations and migration routes for passerines that winter here. If successful, we anticipate being able to use this approach to identify the migration pathways of many other Pacific coast species. Survival rates of wintering sparrows, including the Fox Sparrow, were investigated over a period of 13 years at the Coyote Creek Field Station in northern California (Sandercock, B.K., and Jaramillo, A., 2002). The key findings of this and other studies that have implications for the proposed project are as follows: • “Winter site fidelity is higher for after hatch year (AHY) birds than for hatch year (HY) birds”; • “Site fidelity of migratory sparrows appears to be flexible among immature birds but becomes fixed with increasing age”; • “Site fidelity is often strong once a wintering area is selected (Ralph and Mewaldt, 1976)”; • “Immature sparrows of subdominant status may have higher mortality during winter or subsequent migration periods”; • “Survival rates of sparrows are apparently constant once a bird becomes an adult (Baker