10.5061/DRYAD.6Q573N606
Portugal, Steven
0000-0002-2438-2352
Royal Holloway University of London
White, Craig
Monash University
Raw data set of pigeon body mass measurements
Dryad
dataset
2021
Royal Society
https://ror.org/03wnrjx87
2021-09-14T00:00:00Z
2021-09-14T00:00:00Z
en
12905 bytes
2
CC0 1.0 Universal (CC0 1.0) Public Domain Dedication
1. Animal-borne logging devices are now commonly used to record and
monitor the movements, physiology and behaviours of free-living animals.
It is imperative that the impacts these devices have on the animals
themselves is minimised. 2. One important consideration is the interaction
between the body mass of the animal, and the mass of the device. 3. Using
captive homing pigeons, we demonstrate that birds lose the equivalent
amount of body mass compared to that of the logging device attached. With
our experiments, we calculated that the compensatory mass loss because of
the logging device equates to a total loss of 1,140 kJ of energy to the
bird, over the 25-day period. This equates to 32% per day of their total
daily energy budget. 4. We suggest that practitioners of biologging give
due consideration to the possibility of a device-induced decrease in body
mass when making decisions regarding device size, and when considering the
period of the time of the year at which devices are attached. 5. It
appears, based on the results of the present study, that device attachment
is likely to be most disruptive during periods of regulated mass change,
especially when periods of mass gain precede periods in which stored
energy reserves are extensively utilised. 6. These findings have
significant consequences for anyone using biologging technology on both
wild and captive volant animals. Further studies utilising captive birds
are now needed to fully understand how context- and species-dependent
physiological responses to externally attached devices are.
Birds and housing A group of 18 homing pigeons (hereonin referred to as
pigeons) were housed at Royal Holloway University of London (Egham, UK).
All birds were a minimum of 15 months old and had lived together since
hatching. The sex of the birds was a 55/45% split (males/females) (mean
body mass at start of the study, 590 ± 75.6 (SD) g). Birds were kept in a
pigeon loft (dimensions 3.6 m (long), 2.4 m (wide)) with ad libitum access
to food and water (see Portugal et al., 2017a; Portugal et al. 2017b for
further husbandry details). Wooden perches (n = 20) were attached to the
sides of the loft, in arrangements of six perches in horizontal rows at
three heights (1 m, 1.30 m, 1.60 m), plus two additional single perches
(1.30 m). Body mass measurements and artificial mass attachment Birds were
weighed twice weekly for four weeks, by being placed in a cotton bag and
weighed using digital scales (0.1 g accuracy, Scales and Balances,
Thetford, UK), before each pigeon was fitted with artificial mass in week
five. The artificial devices mimicked the size and mass of typical logging
devices (30 g, 3.7 x 2.4 x 0.8 cm), both those that are generally used for
studies with birds and those which have been used previously with homing
pigeons [Usherwood et al. 2014; Pettit et al. 2016; Taylor et al. 2019].
The artificial mass was attached to the back of the pigeons using Velcro
strips and epoxy glue (total package mass 30 – 31 g, 5% of the mean body
mass of the pigeon group at start of the study; see Sankey and Portugal
(2019) and Sankey et al. (2021) for further details on logger attachment
to the pigeons). Birds were then weighed twice weekly for the next 18 days
(see Figure 1). On day 18 the artificial loggers were removed, and birds
were again weighed twice weekly for a four-week period. Following the
four-week period, 10 birds were randomly selected to have the artificial
loggers reattached, with the remaining 8 birds having no devices attached.
All birds were then weighed twice weekly for a further 21 days (Figure 1).
Statistical analysis Data were analysed using linear mixed models
implemented in the lme4 [Bates et al. 2015] package of R v3.2.2 [R Core
Team 2016]. The significance of random effects in mixed models was
determined using likelihood ratio tests, and the significance of fixed
effects in mixed models was determined using t-tests with Satterthwaite
approximations to degrees of freedom implemented in the lmerTest package
[Kuznetsova et al. 2016]. The model included a random intercept for
individual identity and a random slope for the effect of time, which
varied among measurement blocks. Data for time and mass were mean centred
and scaled to unit variance prior to analysis. Full statistical findings
can found in Supporting Information: Statistical Outputs.