Mapping Avian Movement in Minnesota

Abstract

The western Great Lakes region is home to one of the most diverse breeding bird communities in North America and is a key migration pathway for a wide array of species, including neotropical migrants and birds that breed in boreal ecosystems. To better understand and document how birds move in this region, we focused on two applications of automated radio telemetry technology: 1) large- and small-scale (local) movements of birds during the non-breeding season (i.e., migration and winter), and 2) local movements of breeding Common Terns and dispersal behavior of both adult and juvenile birds.

Our goal was to assess the utility of using Motus automated telemetry technology at various spatial scales and on a variety of species to study different ecological questions. First, to study timing and behavior of fall migration along the shores of Lake Superior, we focused on two species: Blue Jay (Cyanocitta cristata) and Northern Saw-whet Owl (Aegolius acadicus). Second, we focused on Rusty Blackbirds in the St. Louis River Estuary to document the temporal and geographic use during their fall migratory stopover. Rusty Blackbirds are among the most rapidly declining bird species in North America, but the reasons driving these declines are unknown; a lack of suitable habitat during the migratory and non-breeding seasons is likely a contributing factor. Thousands of Rusty Blackbirds use the north shore of Lake Superior and the SLRE as a migration corridor each spring and fall, yet habitat use and duration of stopover is poorly understood. For this reason, we used automated radio tracking technology to document stopover duration of individual birds in relation to minimum daily temperature and to assess potential differences between sex and age. Third, we focused on documenting winter movement patterns of Black-capped Chickadees (Poecile atricapillus) in an urban-forested landscape: Hartley Park, Duluth MN, USA, to assess how detection rates related to minimum daily temperature and food availability at feeding stations. Black-capped Chickadees are an abundant resident species in our study area and have broad public appeal but are relatively understudied in the winter, particularly in urban settings. Finally, we assessed the utility of automated radio telemetry to study breeding behavior of Common Terns (Sterna hirundo). Common Tern are identified as one of the most vulnerable species at both a federal and state level in the region and as a high priority species for conservation in the state. Interstate Island, located in the SLRE, is one of only two breeding colonies of Common Terns in Lake Superior. Movement of juvenile birds is also a critical piece of the life-history of Common Terns that is not well understood due to previously existing limitations of tracking this age class. The ability to track individuals using the Motus network, which does not require re-encountering the individual to retrieve data, is a huge advancement in tracking of juvenile birds. Documenting breeding behavior and dispersal of adult and juvenile terns will help inform population dynamics, which is particularly important for at-risk and declining populations.