DOI: 10.5061/dryad.51c59zwhf
title: Data from: Sex-specific variation in foraging behavior is related to telomere length in a long-lived seabird

description: Foraging during breeding is a demanding activity linked to breeding
 investment and possibly constrained by individual quality. Telomere
 length, the protective nucleoproteins located at the ends of the
 chromosomes, is considered a trait reflecting somatic maintenance and
 individual quality. Therefore, foraging effort and parental investment may
 be positively related to telomere length, if individuals with longer
 telomeres are of better quality and thus able to maintain better body
 condition and allocate more resources to parental activities. In the brown
 booby (Sula leucogaster), we investigated if telomere length is related to
 body mass (a proxy of condition) and whether variation in foraging
 behavior and provisioning effort is related to telomere length or body
 mass. Then, we explored whether variation in foraging and provisioning
 influences the chick mass growth rate. In 34 pairs nesting in Isla de San
 Jorge, in the Gulf of California, México, we sampled their blood to
 estimate telomere length, measured their body mass, and for 10 days,
 recorded their foraging behavior via global positioning system (GPS)
 loggers and their chick provisioning rate and chicks’ mass growth rate. We
 found a positive relationship between parents’ body mass and telomere
 length. Body mass did not affect foraging behavior. Females with longer
 telomeres were more prone to travel longer distances towards offshore and
 deeper waters than females with shorter telomeres. In contrast, males with
 longer telomere lengths performed more nearshore foraging trips than males
 with shorter telomeres. Chick provisioning rate was unrelated to telomere
 length or body mass, but females fed the chick at a rate 2.4 times greater
 than males. Females’ offshore foraging, but not males’, was positively
 related to chick mass growth rate. Our results suggest that individual
 quality, indicated by telomere length, is an important driver of
 sex-specific, between-individual variation in foraging behavior,
 indirectly affecting offspring condition.
description: <strong>Summary of Field Methods</strong>
 The study was carried out from December 2017 to January 2018 in
 the brown booby breeding colony of Reserva Federal Isla de San Jorge,
 Sonora Mexico. 34 pairs rearing a chick were marked with a numbered flag,
 both parents were banded, their mass (± 20 g) were measured and a blood
 sample (1.5 ml) was obtained from their brachial vein using a sterile and
 heparinized syringe. For a subset of pairs (n = 27) foraging behavior was
 recorded by setting both members of a pair with a global positioning
 system (GPS) logger for roughly 10 days. To evaluate the potential effects
 of carrying a GPS logger on parental behavior, the 7 remaining focal pairs
 were treated identically to the birds with GPS, except they were not given
 a logger. We captured all chicks from focal nests to obtain a blood sample
 (1 ml) for sex determination and measured their beak (± 0.1 mm), ulna (± 1
 mm) and mass (± 1 g), once when their parents were initially captured and
 again 10 days later, to estimate mass increase during the same period when
 the parents were GPS tracked. Chicks’ morphological measures at first
 capture were used to calculate their age (mean age = 26, range = 20 – 32
 days) using growth curves from brown booby chicks of known age previously
 recorded by our group. We performed behavioral observations during the 10
 days when the birds were GPS tracked to determine parental
 provisioning. From adult blood samples we calculated
 the relative telomere length of individuals by real-time qPCR following a
 protocol previously reported for our study species (Guillen-Parra et al.
 2024).
description: # Sex-specific variation in foraging behavior is related to telomere
 length in a long-lived seabird. DATASET.
 [https://doi.org/10.5061/dryad.51c59zwhf](https://doi.org/10.5061/dryad.51c59zwhf) ## Description of the data and file structure **Sex-specific variation in foraging behavior is related to telomere length in a long-lived seabird** In the brown booby (*Sula leucogaster*), we investigated if telomere length is related to body mass (a proxy of condition) and whether variation in foraging behavior and provisioning effort is related to telomere length or body mass. Then, we explored whether variation in foraging and provisioning influences the chick mass growth rate. In 34 pairs nesting in Isla de San Jorge, in the Gulf of California, México, we sampled their blood to estimate telomere length, measured their body mass, and for 10 days, recorded their foraging behavior via global positioning system (GPS) loggers and their chick provisioning rate and chicks’ mass growth rate. ### Files and variables #### File: Database.xlsx **Description:**  ##### Variables * Note: “NA” within the database stands for “Not Available” data | Variable Name | **Type of variable** | **Units of measure** | **Description** | | :--------------------------- | :------------------- | :------------------------------------------------ | :---------------------------------------------------------------------------------------------------------------------------------------------- | | Nest | Categorical | Not applicable | Number assigned to each focal nest | | Sex | Categorical | Not applicable | Sex of adults: male or female | | Date | Continuous | Julian days | Date when sampling started | | Telomere length | Continuous | Ratio (Telomere region / Single copy gene region) | Telomere length for each individual | | Batch | Categorical | Not applicable | Batch in which telomeres’ assays were done: one or two | | Telomere length standardized | Continuous | Not applicable | Telomere length standardized by batch: (Focal value – Mean telomere length of each batch) / Standard deviation of telomere length of each batch | | Adult mass 1 | Continuous | Grams | Adult mass measure at first capture | | Adult mass 2 | Continuous | Grams | Adult mass measure at second capture | | Adult mass loss | Continuous | Grams | Difference in adults’ mass between the two measures | | Mass standardized | Continuous | Not applicable | Adults’ mass at first capture, standardized by sex: (Focal value – Mean mass of each sex) / Standard deviation of mass of each sex | | Ulna length | Continuous | Millimeters | Adults’ ulna length measure at first capture | | Ulna standardized | Continuous | Not applicable | Adults’ ulna length standardized by sex: (Focal value – Mean ulna length of each sex) / Standard deviation of ulna length of each sex | | GPS | Categorical | Not applicable | Whether an individual was set with a GPS: yes or no | | Azimuth | Continuous | Degrees | Azimuth centroid values of foraging trips | | Depth | Continuous | Meters | Mean maximum ocean depth of foraging trips | | Distance | Continuous | Kilometers | Mean distance traveled during foraging trips | | Foraging PCA | Continuous | Not applicable | Principal component of foraging behavior, composed of azimuth, depth and distance | | Provisioning rate | Continuous | No. feedings / total observed time | Rate of adults’ food provisioning to their offspring | | Begging rate | Continuous | No. beggings / adults’ time at the nest | Rate of chicks’ begging to their parents | | Chicks’ mass 1 | Continuous | Grams | Chicks’ mass measure at first capture | | Ln chicks’ mass 1 | Continuous | Not applicable | Chicks’ mass measure at first capture (natural logarithm transformed) | | Chicks’ mass 2 | Continuous | Grams | Chicks’ mass measure at second capture | | Ln Chicks’ mass 2 | Continuous | Not applicable | Chicks’ mass measure at second capture (natural logarithm transformed) | | Days between mass measures | Continuous | Days | Number of days elapsed between the two chicks’ mass measures | | Chicks’ mass growth rate | Continuous | Not applicable | Chicks’ mass growth rate, calculated as the difference between the two mass measures (ln), divided by the number of days between measures | | Chicks’ age | Continuous | Days | Chicks’ age | | Chicks’ sex | Categorical | Not applicable | Sex of chicks: male or female | ## Code/software Statistical analyses were run in R (v 3.5.; 1 R Core Team 2018). Code is uploaded as Software in Related Works. \## Upload necessary libraries library(car) library(lme4) library(rptR) library(lavaan)