DOI: 10.5061/dryad.0p2ngf1zz
title: Diurnal timing of nonmigratory movement by birds: the importance of foraging spatial scales

description: Timing of activity can reveal an organism’s efforts to optimize foraging
 either by minimizing energy loss through passive movement or by maximizing
 energetic gain through foraging. Here, we assess whether signals of either
 of these strategies are detectable in the timing of activity of daily,
 local movements by birds. We compare the similarities of timing of
 movement activity among species using six temporal variables: start of
 activity relative to sunrise, end of activity relative to sunset, relative
 speed at midday, number of movement bouts, bout duration, and proportion
 of active daytime hours. We test for the influence of flight mode and
 foraging habitat on the timing of movement activity across avian guilds.
 We used 64570 days of GPS movement data collected between 2002 and 2019
 for local (non-migratory) movements of 991 birds from 49 species,
 representing 14 orders. Dissimilarity among daily activity patterns was
 best explained by flight mode. Terrestrial soaring birds began activity
 later and stopped activity earlier than pelagic soaring or flapping birds.
 Broad-scale foraging habitat explained less of the clustering patterns
 because of divergent timing of active periods of pelagic surface and
 diving foragers. Among pelagic birds, surface foragers were active
 throughout the day while diving foragers matched their active hours more
 closely to daylight hours. Pelagic surface foragers also had the greatest
 daily foraging distances, which was consistent with their daytime activity
 patterns. This study demonstrates that flight mode and foraging habitat
 influence temporal patterns of daily movement activity of birds.
description: Data were compiled from previously collected GPS movement
 datasets. We include days with 8+ h of data, and exclude migrations
 &gt; 500 km long. For colonial nesting pelagic birds, we compare only
 days with known foraging trips. Dataset here includes
 the six temporal variables used in our study, measured at the hourly and
 daily scale.
description: Mallon et al. 2020. Diurnal timing of nonmigratory movement by
 birds: the importance of foraging spatial scales. Journal of Avian
 Biology The dryad repository contents include the
 following data:<br> 1. Final dataset used in analysis:
 mallon2020_trait_data.csv<br> 2. Original hourly data measures of
 several temporal variables: mallon2020_hr_data.csv<br> 3. Original
 daily data measures of several temporal variables:
 mallon2020_day_data.csv<br> 4. Final morphological data used in
 analysis: mallon2020_morpho_data.csv Data columns of
 note:<br> active.hr = if individual is active or inactive, based on
 threshold defined in Mallon et al. 2020<br> mspeed = mean speed
 during active hours<br> n.hrs = number of location hours per
 day<br> dsunrise.min = first activity, relative to sunrise<br>
 dsunset.max = last activity, relative to sunset<br> midday.speed =
 hourly speed nearest to solar noon<br> prop.diel = proportion of
 active hours between sunrise and sunset<br> n.periods.activity =
 number of movement bouts<br> activity.dur = mean duration of
 movement bouts<br> r2n = maximum net squared displacement from the
 beginning of the day (m)<br> mean.r2n = mean net squared
 displacement from the beginning of the day (m)<br> median.r2n =
 median net squared displacement from the beginning of the day
 (m) The dryad repository contents include the following
 scripts, for use with R 4.0.2:<br> 1. Code necessary to create
 mallon2020_trait_data.csv from mallon2020_hr_data.csv and
 mallon2020_day_data.csv: mallon2020_trait_database.R<br> 2. Code
 necessary to recreate analyses: mallon2020_results.R<br> 2. Custom
 functions necessary for mallon2020_results.R:
 mallon2020_functions.R