DOI: 10.5061/dryad.crjdfn372
title: Cerulean Warbler light-level geolocator data

description: The Cerulean Warbler (Setophaga cerulea) is a declining
 Nearctic-Neotropical migratory species of conservation concern.
 Implementing full annual cycle conservation strategies to facilitate
 recovery has been difficult because we know little about the migratory
 period or connectivity between North American breeding regions and South
 American non-breeding regions. Between 2014–2017, we deployed geolocators
 on 282 males at 13 study sites throughout the species’ range with the
 objectives of a) evaluating the strength of connectivity between breeding
 and non-breeding regions; b) identifying approximate routes and stopover
 regions, and c) documenting migration phenology. We retrieved migration
 data from 28 birds and most (14/15; 93%) Appalachian-breeders overwintered
 in the Colombian/Venezuelan Andes, whereas 5/7 (71%) breeders from the
 Ozarks overwintered in the southwestern portion of their non-breeding
 range in Peru/Ecuador. During spring migration, over a 26 d ± 1.2 (SE)
 period, birds (n = 23) staged at multiple stopover locations between
 Panama and southern Mexico. The migratory periods were substantial and
 approximately equal in duration: 38 ± 2 d (SE) in fall and 42 d ± 2 (SE)
 in spring. Based on the observed connectivity pattern, conservation of
 Appalachian breeding populations should focus on forest protection and
 restoration in premontane/lower montane forests of Colombia and Venezuela,
 whereas Ozark breeding population conservation should focus efforts in
 Ecuador and Peru. Additionally, protections of forests used by ceruleans
 during stopovers throughout Central America and southern Mexico, in
 southeastern United States coastal areas, and in the Mississippi Alluvial
 Valley are likely to have high conservation value for this species.
description: We deployed 257 light-level geolocators on male Cerulean
 Warblers (<em>Setophaga cerulea</em>) across 12 study sites
 located throughout the breeding range from 2014–2016. A year after
 deployments, we recovered geolocator data from 26 birds that were
 recaptured with Biotrack (Wareham, UK) model ML6340 units or Migrate
 Technology (Cambridge, UK) model Intigeo-Intigeo-P30Z11-7 units. Biotrack
 units recorded light levels along with timestamps (in GMT) every two
 minutes as .lig files, and Migrate units recorded light levels along with
 timestamps (in GMT) every 5 minutes for 6–13 months as .lux files, both of
 which we processed and analyzed largely using the R packages "TwGeos
 and SGAT". Analyses of these light-level data files allow us to
 estimate approximate latitudes and longitudes based on length of day and
 twilight times encountered by Cerulean Warblers across their entire annual
 cycle as they migrate between North and South America. Our geolocation
 analysis methods are described in "Cerulean Warblers
 (<em>Setophaga cerulea</em>) exhibit parallel migration
 patterns and multiple migratory stopovers within the Central American
 isthmus". 
description: The data files included with this submission can be opened with
 Microsoft Excel or any program that opens .csv files.