Golden Eagle Migratory Behaviors in Response to Arctic Warming Will the early bird catch the worm or a cold? Scott LaPoint 1,2, Gil Bohrer 3, Sarah Davidson 2,3, Eliezer Gurarie 4,5, Peter Mahoney 5, & Natalie Boelman 1,6 11 December 2017 1 Lamont-Doherty Earth Observatory, New York, USA, 2 Max-Planck Institute for Ornithology, Radolfzell, Germany, 3 Ohio State University, Ohio, USA, 4 University of Maryland, Maryland, USA, 5 University of Washington, Washington, USA, 6 Columbia University, New York, USA
Golden eagles ability to respond to climate change varies with age Spring departure Spring arrival Fall departure Fall arrival
Golden eagles ability to respond to climate change varies with age Spring departure Spring arrival Fall departure Fall arrival Subadults 1 4 years old
Golden eagles ability to respond to climate change varies with age Subadults 1 4 years old Spring departure Spring arrival Fall departure Fall arrival Adults >4 years old
Latitude How do we know this? Golden eagle tracking data ~ 520,000 locations > 80 eagles 1993 2017 Invaluable data owners and contributors: Alaska Department of Fish and Game (Booms, Brainerd), Aquila Environmental (E & T Craig), Craighead Beringia South (Crandall), H.T. Harvey & Associates (J Smith), National Park Service (Joly, McIntyre), Raptor View Research Institute (Domenech, Shreading), Teton Research Center (Bedrosian), US Fish and Wildlife Service (B Smith, Lewis), US Geological Survey (Katzner, Fuller), University of Alaska Fairbanks (Breed, Eisaguirre), University of Nevada Reno (Brown), West Virginia University (Miller), & the Western Golden Eagle Conservation Trust (Powell, Woodbridge). Longitude
Why is this potential inflexibility in timing important for Golden eagles? - Day-length cue to begin migrating, - Do not attempt to breed until they are 5 years old, - Lay 1 3 eggs per year with a 70% survival rate, and - Typically do NOT re-initiate a clutch if the first fails Golden eagle provisioning chicks; image from Ross Crandall
Why is this potential inflexibility in timing important for Golden eagles? - Day-length cue to begin migrating, - Do not attempt to breed until they are 5 years old, - Lay 1 3 eggs per year with a 70% survival rate, and - Typically do NOT re-initiate a clutch if the first fails Trend (slope) of snow free date (2004 2016) earlier later -4-2 0 2 4 Golden eagle provisioning chicks; image from Ross Crandall Figure from: Koen Hufkens @ github.com/khufkens/mcd10a1
Beginning to understand what these eagles are experiencing % snow cover Adults Subadults 1993-2017
Beginning to understand what these eagles are experiencing % snow cover Adults Spring Fall Subadults 1993-2017
Species vary in their abilities to respond behaviorally Inflexible Flexible For example: Both & Visser 2001 Walther et al. 2002 Parmesan & Yohe 2003 Charmantier et al. 2008 Post & Forchhammer 2008 Forcada & Trathan 2009 Zimova et al. 2014 Boelman et al. 2017
Scott LaPoint sdlapoint@gmail.com @sdlapoint Implications and next steps If adults are triggered to migrate by a fixed cue (i.e., photoperiod), then their ability to adapt on the fly to their dynamic environment could be limited. This is problematic, as they produce few offspring per year, particularly if climate change brings more frequent extreme weather events or affects changes in seasonality. We have much more to do, including modeling of the environmental variables that may influence Golden eagle behaviors and to determine whether these variables are changing over time.
How do we know this? Golden eagle tracking data ~ 520,000 locations > 80 eagles 1993 2017 Invaluable data owners and contributors: Alaska Department of Fish and Game (Booms, Brainerd), Aquila Environmental (E & T Craig), Craighead Beringia South (Crandall), H.T. Harvey & Associates (J Smith), National Park Service (Joly, McIntyre), Raptor View Research Institute (Domenech, Shreading), Teton Research Center (Bedrosian), US Fish and Wildlife Service (B Smith, Lewis), US Geological Survey (Katzner, Fuller), University of Alaska Fairbanks (Breed, Eisaguirre), University of Nevada Reno (Brown), West Virginia University (Miller), & the Western Golden Eagle Conservation Trust (Powell, Woodbridge). Ross Crandall
Species vary in their abilities to respond behaviorally adults subadults Inflexible Flexible For example: Both & Visser 2001 Walther et al. 2002 Parmesan & Yohe 2003 Charmantier et al. 2008 Post & Forchhammer 2008 Forcada & Trathan 2009 Zimova et al. 2014 Boelman et al. 2017
NASA s Arctic Boreal Vulnerability Experiment: Animals on the Move project PIs: Natalie Boelman (lead), Gil Bohrer, Jan Eitel, Laura Prugh, Mark Hebblewhite, & Lee Vierling We re working with a movement data set: 6 species, ~3100 individuals, yielding ~6.6 mil locations, over the last >25 years *For more information on the Animals on the Move project, see Miriam Handler s poster tomorrow in B21F.*
Migration phenology numbers: Day of year Duration (days) Adult Subadult Adult Subadult Spring departure Mar 12 Mar 25 Spring arrival Apr 4 May 5 20 32 Fall departure Oct 7 Sep 20 Fall arrival Nov 8 Nov 3 32 45