Spring Migration Patterns of Male Red-Winged Blackbirds (Agelaius phoeniceus) from Two Migratory Roosts in South Dakota and Minnesota

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

“…Similar to the results of previous banding and color-marking experiments in eastern South Dakota, our data showed that most birds followed the Prairie Pothole Region as they traveled northwest to their breeding territories (Besser et al 1983;Knittle et al 1987;Knittle et al 1996). Although Red-winged Blackbirds are not confined to breeding in this region, they are found here in their highest densities.…”

“…The marker formulation was a 416-L solution consisting of 208 L Carboset ® (an acrylic adhesive; Noveon™ Incorporated, Cleveland, Ohio), 102 L foodgrade propylene glycol, 7.7 kg fluorescent organic pigment (DayGlo ® Color Corporation, Cleveland, Ohio), 1 L each of a defoamer and surfactant, and 106 L water (Knittle et al 1996). We used CP ® nozzles set at 5 (400 micron droplets).…”

“…In spray form the solution dries in 2-3 minutes adhering to the feather surface. Knittle and Johns (1986) found that 5% of marked birds lost their marks within six weeks; however, particles lodged in the barbules can remain until molt (Knittle et al 1996;Otis et al 1986). …”

“…Recovery rates from mass colormarking projects depend on the number marked compared to the size of the study population (Johns et al 1989); however, thousands of birds can be marked in a single application often yielding a rate of return 10 to 20 times that of leg-banding. Aerial mass colormarking has been used to track spring movements of Red-winged Blackbirds from northeastern Missouri and eastern South Dakota (Knittle et al 1987;Knittle et al 1996), short late-summer movements of Redwinged Blackbirds in central North Dakota (Linz et al 1991), and movements of Red-winged Blackbirds between winter roosts in the southcentral U.S. (Harsch 1995*). The marking formulation is environmentally safe at the concentrations used (Bills and Knittle 1986;Knittle and Johns 1986).…”

“…Our objective was to assess migratory dispersal to breeding territories north of the marking site. 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).…”