Flexible timing of annual movements across consistently used sites by Marbled Godwits breeding in Alaska

Seasonal movements and duration of stay at preferred sites by Marbled Godwit ‘6E’ tracked with a solar-powered satellite transmitter (PTT) from 2008–2015, including 8 complete fall (southward; orange circles and lines) and 7 complete spring (northward; green circles and lines) migrations. Solid lines between circles represent locations received during active PTT transmission cycles, and dotted lines represent straight-line interpolations between locations across transmission cycles. Locations during the breeding (Ugashik Bay, Alaska; site A) and nonbreeding seasons (Humboldt Bay, California; site D) are shown by black and red circles, respectively. Barplots (note different scales) represent duration of stay at (A) Ugashik Bay, (B) Controller Bay, Alaska, (C) Grays Harbor, Washington and (D) Humboldt Bay. For Humboldt Bay, the duration of stay spans January 1, and year reflects the winter season (i.e. ‘2008’ refers to duration of stay over the 2008–2009 nonbreeding season). The duration of stay at sites A–C are unknown in 2008 because the PTT was deployed in June, 2008. Similarly, the PTT ceased transmitting on October 4, 2015, precluding the determination of duration of stay at Humboldt Bay over the winter of 2015–2016.

Authors: Daniel R. Ruthrauff, T. Lee Tibbitts, and Robert E. Gill, Jr

Year: 2019

Publication: The Auk

Publication Link: https://academic.oup.com/auk/article-abstract/136/1/uky007/5322226

Access: Subscription

Affiliations: U.S. Geological Survey, Alaska Science Center, Anchorage, Alaska, USA

Corresponding Author: druthrauff@usgs.gov

Funding: Funding for this project was provided by the David and Lucile Packard Foundation and the U.S. Geological Survey’s Ecosystems mission area

Keywords: individual flexibility, migratory connectivity, migratory timing, repeatability, site fidelity

Abstract: The study of avian movement has detailed a spectrum of strategies for the timing and use of sites throughout the annual cycle, from near randomness to complete consistency. New tracking devices now permit the repeated tracking of individual animals throughout the annual cycle, detailing previously unappreciated levels of variation within migratory systems. Godwits (genus Limosa) have featured prominently in studies of avian migration, but information derived from repeated tracking of individuals is limited. The Marbled Godwit subspecies Limosa fedoa beringiae breeds on the central Alaska Peninsula, and little is known about basic aspects of its migration ecology, including the repeatability with which this population times its annual migratory movements or uses migratory and nonbreeding sites. To address these questions, we equipped 9 Marbled Godwits breeding at a site near Ugashik, Alaska, with solar-powered satellite transmitters. We tracked individuals from July, 2008 to October, 2015 and obtained repeat migratory tracks from 5 of these birds. Individuals exhibited
high fidelity to breeding, nonbreeding, and migratory stopover sites across years, but in contrast to congeners that conduct consistently timed, long, nonstop migrations, beringiae Marbled Godwits exhibited low levels of individual- or population level repeatability in the timing of migratory movements. Their relatively short migrations may enable the integration of local environmental cues, potentially facilitating individual flexibility in the timing of annual migratory movements. Curiously, if local cues ultimately drive the timing of Marbled Godwit migratory movements, the population’s relatively constrained distribution during both the breeding and nonbreeding season should serve to synchronize birds if they are responding to similar cues. That our sample of Marbled Godwits nonetheless exhibited within- and between-year variation in the timing of their migratory movements suggests a complex integration of annually variable internal and external cues.

Supplementary Material: None listed

Intrusive Methodologies: Birds captured, banded with metal band and leg flag. Each bird fitted with satellite transmitter that represented 3.5-4.5% of body mass.

Citizen Science: None

Conservation: Results have conservation implications but not specifically discussed.


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