title: Effects of geolocators on hatching success, return rates, breeding movements, and change in body mass in 16 species of Arctic-breeding shorebirds.
abstract: BACKGROUND
  Geolocators are useful for tracking movements of long-distance migrants, but potential negative effects on birds have not been well studied. We tested for effects of geolocators (0.8-2.0 g total, representing 0.1-3.9 % of mean body mass) on 16 species of migratory shorebirds, including five species with 2-4 subspecies each for a total of 23 study taxa. Study species spanned a range of body sizes (26-1091 g) and eight genera, and were tagged at 23 breeding and eight nonbreeding sites. We compared breeding performance and return rates of birds with geolocators to control groups while controlling for potential confounding variables.
  
  
  RESULTS
  We detected negative effects of tags for three small-bodied species. Geolocators reduced annual return rates for two of 23 taxa: by 63 % for semipalmated sandpipers and by 43 % for the arcticola subspecies of dunlin. High resighting effort for geolocator birds could have masked additional negative effects. Geolocators were more likely to negatively affect return rates if the total mass of geolocators and color markers was 2.5-5.8 % of body mass than if tags were 0.3-2.3 % of body mass. Carrying a geolocator reduced nest success by 42 % for semipalmated sandpipers and tripled the probability of partial clutch failure in semipalmated and western sandpipers. Geolocators mounted perpendicular to the leg on a flag had stronger negative effects on nest success than geolocators mounted parallel to the leg on a band. However, parallel-band geolocators were more likely to reduce return rates and cause injuries to the leg. No effects of geolocators were found on breeding movements or changes in body mass. Among-site variation in geolocator effect size was high, suggesting that local factors were important.
  
  
  CONCLUSIONS
  Negative effects of geolocators occurred only for three of the smallest species in our dataset, but were substantial when present. Future studies could mitigate impacts of tags by reducing protruding parts and minimizing use of additional markers. Investigators could maximize recovery of tags by strategically deploying geolocators on males, previously marked individuals, and successful breeders, though targeting subsets of a population could bias the resulting migratory movement data in some species.
authors.affiliation: Division of Biology, Kansas State University, Manhattan, KS USA.
authors.forename: Emily L
authors.initials: EL
authors.lastname: Weiser
authors.affiliation: US Fish and Wildlife Service, Anchorage, AK USA.
authors.forename: Richard B
authors.initials: RB
authors.lastname: Lanctot
authors.affiliation: Manomet Center for Conservation Sciences, Manomet, MA USA.
authors.forename: Stephen C
authors.initials: SC
authors.lastname: Brown
authors.affiliation: CESAM, Universidade de Aveiro, Campus Universitário de Santiago, Aveiro, Portugal ; South Iceland Research Centre, University of Iceland, Selfoss, Iceland.
authors.forename: José A
authors.initials: JA
authors.lastname: Alves
authors.affiliation: Ecology Group, Institute of Agriculture and Environment, Massey University, Palmerston North, New Zealand.
authors.forename: Phil F
authors.initials: PF
authors.lastname: Battley
authors.affiliation: Wildlife Conservation Society, Fairbanks, AK USA.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Bentzen
authors.affiliation: Département de Biologie, Chimie et Géographie and Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, QC Canada.
authors.forename: Joël
authors.initials: J
authors.lastname: Bêty
authors.affiliation: Prince William Sound Science Center, Cordova, AK USA.
authors.forename: Mary Anne
authors.initials: MA
authors.lastname: Bishop
authors.affiliation: Department of Biology and Wildlife, University of Alaska Fairbanks, Fairbanks, AK USA.
authors.forename: Megan
authors.initials: M
authors.lastname: Boldenow
authors.affiliation: Université de Bourgogne Franche-Comté, Dijon, France ; Laboratoire Chrono-Environnement UMR CNRS 6249, Besançon, France ; Groupe de Recherche en Ecologie Arctique, Francheville, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Bollache
authors.affiliation: Fallon, NV USA.
authors.forename: Bruce
authors.initials: B
authors.lastname: Casler
authors.affiliation: Victorian Wader Study Group, Victoria, Australia.
authors.forename: Maureen
authors.initials: M
authors.lastname: Christie
authors.affiliation: Queensland Wader Study Group, Shailer Park, Queensland Australia.
authors.forename: Jonathan T
authors.initials: JT
authors.lastname: Coleman
authors.affiliation: Chair in Global Flyway Ecology, Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands.
authors.forename: Jesse R
authors.initials: JR
authors.lastname: Conklin
authors.affiliation: Department of Biological Sciences, Simon Fraser University, Burnaby, BC Canada.
authors.forename: Willow B
authors.initials: WB
authors.lastname: English
authors.affiliation: ABR, Inc. - Environmental Research and Services, Anchorage, AK USA ; Manomet Center for Conservation Sciences, Manomet, MA USA ; US Fish and Wildlife Service, Anchorage, AK USA.
authors.forename: H River
authors.initials: HR
authors.lastname: Gates
authors.affiliation: Laboratoire Biogéoscience, Université de Bourgogne, Dijon, France ; Groupe de Recherche en Ecologie Arctique, Francheville, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Gilg
authors.affiliation: Département de Biologie, Chimie et Géographie and Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, QC Canada ; Canada Research Chair in Polar and Boreal Ecology, Université de Moncton, Moncton, NB Canada.
authors.forename: Marie-Andrée
authors.initials: MA
authors.lastname: Giroux
authors.affiliation: Victorian Wader Study Group, Victoria, Australia ; Australasian Wader Studies Group, Victoria, Australia.
authors.forename: Ken
authors.initials: K
authors.lastname: Gosbell
authors.affiliation: Australasian Wader Studies Group, Victoria, Australia ; Global Flyway Network, Broome, WA Australia.
authors.forename: Chris
authors.initials: C
authors.lastname: Hassell
authors.affiliation: Helmericks Homestead, Colville Village, AK USA.
authors.forename: Jim
authors.initials: J
authors.lastname: Helmericks
authors.affiliation: Cornell Lab of Ornithology, Cornell University, Ithaca, NY USA.
authors.forename: Andrew
authors.initials: A
authors.lastname: Johnson
authors.affiliation: Ecology Department, Icelandic Institute of Natural History, Gardabaer, Iceland.
authors.forename: Borgný
authors.initials: B
authors.lastname: Katrínardóttir
authors.affiliation: Department of Ecology, University of Oulu, Oulu, Finland.
authors.forename: Kari
authors.initials: K
authors.lastname: Koivula
authors.affiliation: Division of Biology, Kansas State University, Manhattan, KS USA.
authors.forename: Eunbi
authors.initials: E
authors.lastname: Kwon
authors.affiliation: Département de Biologie, Chimie et Géographie and Centre d'Études Nordiques, Université du Québec à Rimouski, Rimouski, QC Canada.
authors.forename: Jean-Francois
authors.initials: JF
authors.lastname: Lamarre
authors.affiliation: Groupe de Recherche en Ecologie Arctique, Francheville, France ; Institute of Animal Ecology and Nature Education, Gonterskirchen, Germany.
authors.forename: Johannes
authors.initials: J
authors.lastname: Lang
authors.affiliation: Centre for Wildlife Ecology, Simon Fraser University, Burnaby, BC Canada.
authors.forename: David B
authors.initials: DB
authors.lastname: Lank
authors.affiliation: Canada Research Chair in Polar and Boreal Ecology, Université de Moncton, Moncton, NB Canada.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lecomte
authors.affiliation: Audubon Society of Portland, Portland, OR USA.
authors.forename: Joe
authors.initials: J
authors.lastname: Liebezeit
authors.affiliation: US Fish and Wildlife Service, Portland, OR USA.
authors.forename: Vanessa
authors.initials: V
authors.lastname: Loverti
authors.affiliation: Department of Biology, Trent University, Peterborough, ON Canada ; Department of Multidisciplinary Studies, York University Glendon Campus, Toronto, ON Canada.
authors.forename: Laura
authors.initials: L
authors.lastname: McKinnon
authors.affiliation: Victorian Wader Study Group, Victoria, Australia ; Australasian Wader Studies Group, Victoria, Australia.
authors.forename: Clive
authors.initials: C
authors.lastname: Minton
authors.affiliation: New Jersey Audubon Society, Cape May, NJ USA.
authors.forename: David
authors.initials: D
authors.lastname: Mizrahi
authors.affiliation: Department of Biology, Trent University, Peterborough, ON Canada.
authors.forename: Erica
authors.initials: E
authors.lastname: Nol
authors.affiliation: Department of Ecology, University of Oulu, Oulu, Finland.
authors.forename: Veli-Matti
authors.initials: VM
authors.lastname: Pakanen
authors.affiliation: Department of Biology, Trent University, Peterborough, ON Canada.
authors.forename: Johanna
authors.initials: J
authors.lastname: Perz
authors.affiliation: Delaware Bay Shorebird Project, Ambler, PA USA.
authors.forename: Ron
authors.initials: R
authors.lastname: Porter
authors.affiliation: Environment Canada, Yellowknife, NT Canada.
authors.forename: Jennie
authors.initials: J
authors.lastname: Rausch
authors.affiliation: Chair in Global Flyway Ecology, Conservation Ecology Group, Groningen Institute for Evolutionary Life Sciences (GELIFES), University of Groningen, Groningen, The Netherlands ; Arctic Research Centre, Department of Bioscience, Aarhus University, Roskilde, Denmark.
authors.forename: Jeroen
authors.initials: J
authors.lastname: Reneerkens
authors.affiliation: Department of Ecology, University of Oulu, Oulu, Finland.
authors.forename: Nelli
authors.initials: N
authors.lastname: Rönkä
authors.affiliation: US Fish and Wildlife Service, Anchorage, AK USA.
authors.forename: Sarah
authors.initials: S
authors.lastname: Saalfeld
authors.affiliation: University of Montana, Missoula, MT USA.
authors.forename: Nathan
authors.initials: N
authors.lastname: Senner
authors.affiliation: Groupe de Recherche en Ecologie Arctique, Francheville, France ; Institut für Landespflege, University of Freiburg, Freiburg, Germany.
authors.forename: Benoît
authors.initials: B
authors.lastname: Sittler
authors.affiliation: Environment Canada, Ottawa, ON Canada.
authors.forename: Paul A
authors.initials: PA
authors.lastname: Smith
authors.affiliation: Yukon Delta National Wildlife Refuge, US Fish and Wildlife Service, Bethel, AK USA.
authors.forename: Kristine
authors.initials: K
authors.lastname: Sowl
authors.affiliation: Department of Geography and Environmental Studies, University of Alaska Anchorage, Anchorage, AK USA.
authors.forename: Audrey
authors.initials: A
authors.lastname: Taylor
authors.affiliation: US Geological Survey, Anchorage, AK USA.
authors.forename: David H
authors.initials: DH
authors.lastname: Ward
authors.affiliation: Surrey, BC Canada.
authors.forename: Stephen
authors.initials: S
authors.lastname: Yezerinac
authors.affiliation: Division of Biology, Kansas State University, Manhattan, KS USA.
authors.forename: Brett K
authors.initials: BK
authors.lastname: Sandercock
keywords: Breeding success; Geologger; Global location sensor (GLS); Research impacts; Return rates; Tracking methods; Waders