Movement and Migration Patterns of Red-Winged Blackbirds: A Continental Overview

Spring Dispersal Patterns of Red-winged Blackbirds, <em>Agelaius phoeniceus</em>, Staging in Eastern South Dakota

“…Usually, recovery rates are inversely related to the distance traveled from a marking site because unmarked populations arriving by other routes from other areas dilute the proportion of marked birds. Although it is conceivable that the Red-winged Blackbird population marked at Lake Thompson in 1985 migrated beyond traditional nesting areas and immigrated into Canada, perhaps seeking better wetland conditions, band recoveries collected over several decades have shown that Red-winged Blackbirds usually return to within 100 km of their natal sites (Nero 1956;Dolbeer 1978). If Red-winged Blackbirds were not philopatric, but nomadic or irruptive, we contend that large fluctuations in BBS counts would occur among physiographic regions comprising the Prairie Pothole Region.…”

“…The core polygon encompassed the breeding range of birds having a high probability of causing early damage to sunflowers. The peripheral polygon contained the surrounding breeding range of birds that were capable (with only short pre-migratory movements) of entering the core area during the early damage period (midAugust -early September) (Dolbeer 1978;Gammell et al 1986). The outside-peripheral polygon contained the birds farthest removed from the core area and encompassed the rest of the study area not covered by the core and peripheral polygons.…”

“…Previous research has shown that color-marked male Red-winged Blackbirds staging in eastern South Dakota during spring were in part destined for breeding grounds in or near concentrated sunflower production; however, these data were collected over 15 years ago (Knittle et al 1987;Knittle et al 1996). Population management programs, when used at sites far from the locality where actual damage occurs, must be based on a thorough and contemporary knowledge of movements of individual populations (Dolbeer 1978). We believed it necessary to replicate the marking studies because changes may have occurred in migratory patterns.…”

“…This period is before en masse blackbird migration, and the majority of these birds are of local origin. Most will remain within 200 km of their natal sites until molt completion (or near completion) in late August and early September (Dolbeer 1978;Besser et al 1983;Linz et al 1983 Linz et al 2002). By late summer, the Red-winged Blackbird population responsible for most of the sunflower damage in the Prairie Pothole Region is about 39 (±8.8) million (Peer et al 2003).…”

“…It has been defined generally as that point of abundance where all positive values of the species have been overwhelmed by negative values created by the sheer numbers of individuals (Conover 2002 Because blackbird damage to sunflower is a localized phenomenon occurring within the broader region of the northern Great Plains (Peer et al 2003), it is necessary to identify specific origins of local populations before implementing any strategy of population management. Although leg-banding has provided valuable insights into migratory timing and dispersal of Red-winged Blackbirds (Dolbeer 1978), this method draws its samples randomly from regional populations. Moreover, it is labor intensive in both its capturing and ringing methods; these drawbacks combined with natural annual mortality of Red-winged Blackbirds cause data to be parsed over several years because of extremely low rates of band returns (<0.5%, Besser et al 1983;Gammell et al 1986;Stehn 1989).…”