Dynamics of Low-Level Organochlorines in Adult Cackling Geese over the Annual Cycle

Abstract

To study patterns of acquisition of pollutants during migration, we monitored organochlorines in cackling Canada geese (Branta canadensis minima) over the annual cycle from 1973 to 1974. This annual cycle is characterized by a mostly uncontaminated breeding area (Alaska's Yukon-Kuskokwim river deltas), but mostly diffuse, contaminated nonpoint sources on the southern migration routes and wintering areas (the Klamath Basin of Oregon and California and California's Central Valley). Levels of all organochlorine (OC) compounds detected were in the ppb (ng/g) range and not believed to be of overt detrimental concentrations. Changes in total residue body-burdens followed patterns that could be related to reported OC use only on a qualitative basis. Residue variation was partly due to seasonal physiological changes and pharmacodynamic characteristics of the OC compounds detected, but most variation was still probably the result of variations in exposure (estimated by us through residue body-burdens). Variations in the patterns of gain suggest slightly different exposures to different compounds during migration and wintering, although all residues rapidly increased during this phase of the annual cycle. Over most of the annual cycle both sexes retained similar residue levels. Concentrations of toxaphene, the most-used organochlorine insecticide in California during this study, were below our detection limits. Occurrence of several banned compounds may indicate their illegal uses in some areas. Estimated persistences of the OC residues (in relation to PCB's) were as follows: very low-endrin; low-DDT + DDD, dieldrin, and chlordane/heptachlor metabolites; moderate-DDE; high-PCB's. At present contamination levels, cackling geese should eliminate all these residues but PCB's and DDE annually. J. WILDL. MANAGE. 48(4):1112-1127 There is a need to continue to study persistent organochlorine pollutants (OC's) in northern wildlife species (1) to determine potential problems of persistence, (2) to monitor changing OC contamination patterns, and (3) to quantify the dynamics of such chemicals under variable conditions. The acquisition of pollutants during migration is a continuing issue of interest (see Anderson et al. 1969; Ulfstrand and SOSdergren 1972; Charnetski 1976; Babcock and Flickinger 1977; Flickinger 1979; Henny et al. 1982b, 1984; Clark and Krynitsky 1983; White et al. 1983). It is important to understand and document such phenomena as pollution acquisition problems in migratory birds increase or decrease because they transcend political boundaries and complicate management and policy-making. Acquisition of pollutants during migration is an often discussed but seldom documented natural phenomenon. Keith (1968:34) summarized residue data relating to fish-eating birds from local areas with high or specific contaminations, or point sources. Such point sources have often resulted in highly variable residues among individuals of the same population because only some individuals were exposed. Similar observations have been reported for some wideranging raptors (Cade et al. 1972, Lincer and Sherburne 1974), and unusual point sources are also known to complicate regional interpretations of residue levels (Fleming and O'Shea 1980). Diffusion occurs over time, however, so that regional (a d less variable), or nonpoint sources, of contamination may become prevalent 1112 J. Wildl. Manage. 48(4):1984 This content downloaded from 157.55.39.158 on Fri, 18 Nov 2016 04:13:59 UTC All use subject to http://about.jstor.org/terms ORGANOCHLORINE DYNAMICS IN CACKLING GEESE * Anderson et al. 1113 (Overcash and Davidson 1980:iii-vi, 23104), in some cases even on a continental or global scale (see review by Peakall 1980). The annual movements of cackling Canada geese are well known as are their seasonal changes in body composition (Fig. 1). The areas where these birds spend most of their time are relatively small. in geographical extent. They winter mostly in the Central Valley of California, migrate through the Klamath Basin at the Oregon/California border, and breed on the Yukon and Kuskokwim river deltas in Alaska (Fig. la). Pesticide use is extensive and well documented in California (Painter and Wedge 1975), and the goose's distribution is limited enough such that adults of the subspecies are suitable indicators of regional contamination patterns (Fig. la). Ours was not a study of one species per se, but one of residue dynamics in a migratory species having movements into and out of areas expected to be contaminated. Such data are of interest not only in monitoring a specific region but in establishing pharmacodynamic patterns that might be predicted from a given life history and chemical behavior pat-