DOI: 10.5061/dryad.6m905qgbz
title: The combination of miniaturized GPS/VHF tags and soluble backpack harness as an effective method for tracking lightweight and elusive birds

description: The use of Global Positioning System (GPS) tags is increasingly widespread
 for wildlife tracking in many ecological studies. However, GPS tags are
 often too heavy for lightweight species or require recapturing the animal
 to download the data. In this study, we designed a water-soluble backpack
 harness linked to a handmade GPS+VHF tag combination to obtain GPS data
 without the need to recapture the animal. Once the harness disintegrates
 after rainfall, the GPS+VHF tags can be located via radiotracking, and the
 dataset can be downloaded. Specifically, we (1) assessed the most
 effective way to attach the VHF tag to the GPS (to minimize data loss in
 terms of quantity and quality), (2) tested effects on wild birds, and (3)
 evaluated the efficiency of device retrieval by tagging Dupont's
 larks (Chersophilus duponti), a small (~40 g), elusive passerine. Results
 showed that the VHF tag should be attached to the GPS at a 45º angle to
 avoid negative effects on GPS data. To reduce GPS location error, we
 recommend using data obtained with ≥5 satellites and, ideally, &gt;7
 satellites, for average errors less than 10 meters. All devices (100%)
 were detached from the birds and successfully retrieved. No adverse
 effects were detected in the birds after the tagging period, and all birds
 remained in their territories.  This methodology can be highly
 useful for studies involving lightweight and elusive fauna. Additionally,
 our system reduces stress on individuals by minimizing the number of
 captures required, while also lowering human resource costs, as a single
 person can carry out the entire process.
description: # The combination of miniaturized GPS/VHF tags and soluble backpack
 harness as an effective method for tracking lightweight and elusive birds
 Dataset DOI: [10.5061/dryad.6m905qgbz](10.5061/dryad.6m905qgbz) ##
 Description of the data and file structure In the set of files, you will
 find the data matrix and the R script where the analytical process is
 detailed step by step with thorough explanations. Each column of the data
 matrix and each file used is referenced with the same name in the R
 scripts.  ### Files and variables We have submitted our raw data on the
 field trials assessing the accuracy of the nanoFix® GEO-mini
 (**Distance_Gamma2.csv**), the evaluation of their effect on bird weight
 (**weight_changes_t_test.csv**), and the data used to produce Figures 3
 (**Figure_3**) and 4 (**Figure_4**). #### Descriptions
 **Distance_Gamma2.csv** * Tag:Identification code of each nanoFix®
 GEO-mini * Code_test: Code for each field trial conducted * Position:
 Classification for assessing the effect of attaching the VHF tag to the
 nanoFix® GEO-mini: without VHF tag attached, attached in an elevated
 position, attached in a position parallel to the nanoFix® GEO-mini. *
 timestamp: Date and time data (excluding seconds) combined and used as a
 random factor. * satellites: Number of satellites used by the nanoFix®
 GEO-mini to record each location. * Distance: Distance (m) calculated
 between the actual field location of the nanoFix® GEO-mini (recorded using
 a handheld GPS) and the location registered by the nanoFix® GEO-mini. *
 Accuracy: Location accuracy indicator provided in the data output by the
 manufacturer (Pathtrack). **weight_changes_t_test.csv** * Individual_code:
 Numeric identification code of each ringed bird. * GPS_deployment: Whether
 the bird carried a device (Yes/No) * Capture1: Date and time of the
 bird's first capture * weight1: Bird's weight at first capture *
 Capture 2: Date and time of the bird's second capture * weight2:
 Timestamp of the bird’s recapture * Time (days): Time elapsed (in days)
 between the two captures * Weight_difference: Weight difference (g)
 between the two captures * weight_change(%): Percentage change in weight
 between the two captures * Mean: Average percentage of weight loss for the
 group of birds that carried a device and for those that did not. *
 Average_date: Mean date between capture and recapture * Average Day: Mean
 day between dates * daily_weight_change: Daily weight loss or gain (g) *
 daily weight change(%): Daily percentage of weight loss or gain (g) *
 Average: Mean daily percentage weight loss * SE: Standard error of the
 mean daily percentage weight loss * Sex: Sex of each bird *
 Days_with_device: Number of days the device was carried **Figure_3** * Num
 satélites: Number of satellites used to obtain each point in the field
 trials * Without VHF: Number of locations recorded by the nanoFix®
 GEO-mini when no VHF tag was attached * Raised: Number of locations
 recorded by the nanoFix® GEO-mini when a VHF tag was attached at a 45º
 elevated position * Parallel: Number of locations recorded by the nanoFix®
 GEO-mini when a VHF tag was attached in a parallel position * Without
 VHF(%): Percentage of locations recorded by the nanoFix® GEO-mini when no
 VHF tag was attached * Raised(%): Percentage of locations recorded by the
 nanoFix® GEO-mini when a VHF tag was attached at a 45º elevated position *
 Parallel(%): Percentage of locations recorded by the nanoFix® GEO-mini
 when a VHF tag was attached in a parallel position **Figure_4** *
 Satellites: Number of satellites used to record the locations * Without
 VHF: Average number of locations recorded by the nanoFix® GEO-mini without
 any attached tag for a given number of satellites * conf.low_WV: Lower
 confidence interval limit of the average number of locations recorded by
 the nanoFix® GEO-mini without any attached tag, for a given number of
 satellites * conf.high_WV: Upper confidence interval limit of the average
 number of locations recorded by the nanoFix® GEO-mini without any attached
 tag, for a given number of satellites * Raised: Average number of
 locations recorded by the nanoFix® GEO-mini with a VHF tag attached in a
 45º elevated position, for a given number of satellites * conf.low_R:
 Lower confidence interval limit of the average number of locations
 recorded by the nanoFix® GEO-mini with a VHF tag attached at a 45º
 elevated position, for a given number of satellites * conf.high_R: Upper
 confidence interval limit of the average number of locations recorded by
 the nanoFix® GEO-mini with a VHF tag attached at a 45º elevated position,
 for a given number of satellites * Parallel: Average number of locations
 recorded by the nanoFix® GEO-mini with a VHF tag attached in a parallel
 position, for a given number of satellites * conf.low_P: Lower confidence
 interval limit of the average number of locations recorded by the nanoFix®
 GEO-mini with a VHF tag attached in a parallel position, for a given
 number of satellites * conf.high_P: Upper confidence interval limit of the
 average number of locations recorded by the nanoFix® GEO-mini with a VHF
 tag attached in a parallel position, for a given number of satellites *
 Parallel_LOW: Difference between the mean and the lower confidence for
 'Parallel' * Parallel_UP: Difference between the mean and the
 upper confidence for 'Parallel' * Raised_LOW: Difference between
 the mean and the lower confidence for 'Raised' * Raised_UP:
 Difference between the mean and the upper confidence for
 'Raised' * Without VHF_LOW: Difference between the mean and the
 lower confidence for 'Without VHF' * Without VHF_UP: Difference
 between the mean and the upper confidence for 'Without VHF' ###
 Code/Software: GLMM\_Analysis R is required to run *GLMM_Analysis*; the
 script was created using version 4.4.2 (2024-10-31 ucrt) Annotations are
 provided throughout the script through 1) library loading, 2) dataset
 loading and cleaning, 3) analyses, and 4) figure creation.