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

Abstract

Red-winged Blackbirds (Agelaius phoeniceus) are very abundant summer residents throughout the Prairie Pothole Region of central North America. In late summer they assemble in post-breeding flocks that cause significant amounts of agricultural damage, particularly in sunflower fields near natal sites. In April 2001, we aerially color-marked ~370,000 Red-winged Blackbirds near Badger, South Dakota (44°48'N, 97°21'W), to determine if migrants staging here were summer residents in sunflower production areas ~350 km to the northwest. We measured patterns of migratory dispersal by collecting birds in 54 randomly selected blocks in the northcentral U.S. and the Prairie Provinces of Canada. The marked specimens (n = 33) were categorized into three polygons based on analyses of banding and re-sighting data and proximity to concentrated sunflower production. We estimated that 82% of the migrants that had staged in eastern South Dakota resided within or on the periphery of the sunflower growing area. These birds probably stay near their breeding territories until at least late August and cause early damage to sunflower, which comprises the majority of damage. Resident birds in Alberta and most of Saskatchewan (18%) might arrive too late in the damage season to impact the sunflower crop significantly.

Escherichia coli, Salmonella, and Mycobacterium avium subsp. paratuberculosis in Wild European Starlings at a Kansas Cattle Feedlot

“…Long-distance migration is stressful on birds, often leading to decreased immune function resulting in enhanced susceptibility to disease (45). As avian wildlife migrate, they make a series of flights interrupted with many stopovers (29). Stopover locations characteristically have dense congregations of birds, which can potentially facilitate pathogen transfer (15,43).…”

Assessment of Bird-management Strategies to Protect Sunflowers

“…In the mid-1990s, a multiyear assessment was conducted on the feasibility of an operational DRC-1339 program for reducing the number of spring-migrating blackbirds in eastern South Dakota , Homan et al 2004). This area is a major stopover site used by millions of blackbirds migrating toward their breeding territories in sunflower production areas approximately 350 km to the northwest , Homan et al 2004).…”

“…This area is a major stopover site used by millions of blackbirds migrating toward their breeding territories in sunflower production areas approximately 350 km to the northwest , Homan et al 2004). Linz and colleagues (2003) demonstrated that thousands of blackbirds could be attracted to small field plots in cornfields during the spring.…”

Longevity of DayGlo fluorescent particle marker used to mark birds in flight pen and field

“…We used the DayGlo Fluorescent particle marker formulation described by Linz et al (1991), Knittle et al (1996), and Homan et al (2004). A 950 mL solution of this formulation was mixed within 30 min of application.…”

“…Knittle et al (1987) marked 10.6 million red-winged blackbirds (Agelaius phoeniceus) in Missouri and South Dakota, USA, with marker. Linz et al (1991) and Homan et al (2004) used a different marker formulation to mark 300 000 and 370 000 blackbirds in North Dakota and South Dakota, USA, respectively. After marking, birds in these studies were systematically shot and collected along migrational pathways or in breeding areas and examined for marker.…”