DOI: 10.5061/dryad.fqz612jpv
title: The importance of nighttime length to latitudinal variation in avian incubation attentiveness

description: Avian incubation provides an opportunity to test how parental behavior and
 ecological conditions interact to shape variation in offspring traits
 along geographic gradients. In particular, the duration of the incubation
 period is shorter at higher latitudes, but the degree to which this
 pattern arises from genetic divergence in rates of growth and development
 versus from parentally-mediated variation in egg temperatures is
 controversial. At higher latitudes parents have higher daytime incubation
 attentiveness, i.e., they spend a greater proportion of the day on the
 nest. However, interpreting latitudinal variation in behavior is
 complicated by latitudinal patterns in ambient temperature and day length.
 Here, we use 24-hour video recordings to compare the incubation behavior
 of orange-crowned warblers (Leiothlypis celata) in California and Alaska
 and test how attentiveness varies between populations and as a function of
 temperature. Birds in Alaska had higher nest attentiveness during the day,
 despite experiencing similar ambient temperatures. However, when analyzed
 over 24-hours, the longer nighttime period in California almost entirely
 canceled out daytime attentiveness differences between populations, and
 differences in 24-hour attentiveness were small. Our work highlights how
 incorporating nighttime incubation behavior qualitatively alters
 latitudinal patterns of attentiveness, and how lower ambient temperatures
 cannot account for the higher attentiveness in a high latitude population.
 These populations differ in their incubation period lengths, and
 differentiating between evolved versus environmentally-induced variation
 in offspring growth and development will help understand the fitness
 consequences of variation in developmental periods.
description: Data collection details are described in the associated
 publication (Sofaer et al. Journal of Avian Biology). Data are based on
 video recordings of orange-crowned warbler (<i>Leiothlypis
 celata</i>) incubation behavior, and observations of incubation
 period length. The data on nest attentiveness are summarized from the on
 and off bout data.
description: Definitions of data columns:
 <strong>OCWA_OnOffBouts.csv</strong>: This file
 contains on and off bout data transcribed from video recordings, and
 associated hourly temperature from nearby weather stations.
 Pop: AK or CA, corresponding to Alaska or
 California NestID: nest identity
 OnDate: date of start of on-bout; format is m/d/yyyy
 OffDate: date of end of on-bout; format is m/d/yyyy
 IncStartTime: time at start of on-bout; format is
 hh:mm:ss IncEndTime: time at end of on-bout; format
 is hh:mm:ss ExcludeON: binary; has value of 1 if
 on-bout duration should be excluded from analyses (e.g., because
 incomplete) ExcludeOFF: binary; has value of 1 if
 off-bout duration should be excluded from analyses (e.g., because
 incomplete) NOTES: description of any uncertinaty in
 video observation or other notes Overnight: binary; 1
 if the on and off times correspond to an overnight period
 OnMin: duration of on-bout (min.) OffMin:
 duration of off-bout (min.) StartHour: integer hour
 of on-bout start time TempC_mean: mean temperature
 (degrees C) during the hour starting at StartHour
 TempC_max: maximum temperature (degrees C) during the hour
 starting at StartHour TempC_min: minimum temperature
 (degrees C) during the hour starting at StartHour
 Precip_mm: total precipitation (mm) recorded during the hour
 starting at StartHour 
 <strong>OCWA_DaytimeAtten.csv</strong>: This file
 contains hourly nest attentiveness during active hours (i.e., excluding
 the overnight period) and associated weather. 
 Pop: AK or CA, corresponding to Alaska or California
 NestID: nest identity Date: date of
 observation; format is m/d/yyyy StartHour: integer
 hour over which atteniveness is summarized Atten.min:
 number of minites on the nest during that hour (maximum of 60)
 TempC_mean: mean temperature (degrees C) during the hour
 starting at StartHour TempC_max: maximum temperature
 (degrees C) during the hour starting at StartHour
 TempC_min: minimum temperature (degrees C) during the hour
 starting at StartHour Precip_mm: total precipitation
 (mm) recorded during the hour starting at StartHour 
 <strong>OCWA_IncPeriod.csv</strong>: Incubation
 period duration data Pop: AK or CA,
 corresponding to Alaska or California NestID: nest
 identity NumEggs: number of eggs observed in
 nest NumHatched: number of young hatched
 clutch_yearday: day of year of clutch completion date
 hatch_yearday: day of year of first egg hatching
 IncLength: duration of incubation period (number of
 days)