DOI: 10.5061/dryad.q573n5tnm
title: Partner intrinsic characteristics influence foraging trip duration, but not coordination of care in wandering albatrosses Diomedea exulans

description: 1. Long-lived monogamous species gain long-term fitness benefits by
 equalising effort during bi-parental care. For example, many seabird
 species coordinate care by matching foraging trip durations within pairs.
 2. Age affects coordination in some seabird species; however, the impact
 of other intrinsic traits, including personality, on potential
 intraspecific variation in coordination strength is less well understood.
 3. The impacts of pair members’ intrinsic traits on trip duration and
 coordination strength were investigated using data from saltwater
 immersion loggers deployed on 71 pairs of wandering albatrosses Diomedea
 exulans. These were modelled against pair members’ age, boldness and their
 partner’s previous trip duration. 4. At the population level, the birds
 exhibited some coordination of parental care that was of equal strength
 during incubation and chick-brooding. However, there was low variation in
 coordination between pairs and coordination strength was unaffected by the
 birds’ boldness or age in either breeding stage. Surprisingly, during
 incubation, foraging trip duration was mainly driven by partner traits, as
 birds that were paired to older and bolder partners took shorter trips.
 During chick-brooding, shorter foraging trips were associated with greater
 boldness in focal birds and their partners, but age had no effect. 5.
 These results suggest that an individual’s assessment of their partner’s
 capacity or willingness to provide care may be a major driver of trip
 duration, thereby highlighting the importance of accounting for pair
 behaviour when studying parental care strategies.
description: Description of methods used for
 collection/generation of data: Intrinsic variables: this population has
 been monitored since the 1960s and so data on the sex, age and partnership
 histories were available for all individuals. Trip durations: 71 wandering albatrosses were
 tagged with saltwater immersion loggers across 7 years. The loggers
 distinguish between dry periods (land or flying) and wet periods (immersed
 in saltwater). Boldness: Responses
 of incubating birds to an approaching human (from a 5m distance) were
 quantified using an ordinal scale from 0-5 (0 = no response; 1 = raises
 head; 2 = rises onto tarsus; 3 = vocalises; 4 = stands up; 5 = vacates
 nest). Higher scores = bolder birds. Partner previous bout (part_prev_bout): the trip
 duration of each bird's partner immediately prior to their own
 foraging trip. Methods for
 processing the data: Trip durations: Periods &gt; 12 hours dry were
 considered to be nest attendance bouts. Periods in between these &gt;
 12-hour dry bouts were considered foraging trips. The length of these is
 the response variable individual trip duration (no_hours). Partner
 (unloggered birds) trip durations were estimated from the loggered birds
 nest attendance bouts. Incubation trips occurred between 16th Dec- Mid
 march (exact date varied depending on patterns for individual pairs).
 Brooding occurred between mid-march and April 11th each year.
 Boldness scores: Observation number,
 observer identity, and bird ID were fitted as fixed effects in a
 generalized linear model. Individual parameter estimates were mean-centred
 at the population level (see Patrick et al., 2013 for a detailed
 description). This created a boldness score of each individual.
description: Software-specific information needed to interpret the data: Data
 processed in R, packages used: library(dplyr) library(MuMIn)
 library(ggplot2) library(lme4) library(tidyverse) library(optimx)
 library(knitr) library(car) library(effects) library(sjPlot)