albatross_eggs_header.Rmd

albatross_eggs_header.Rmd

---
title: "Surface temperatures of albatross eggs and nests"
author: Philipp H. Boersch-Supan^A,B,C^, Leah R. Johnson^D^, Richard A. Phillips^E^,
  Sadie J. Ryan^A,B^
date: ''
output:
  word_document:
    keep_md: yes
    reference_docx: marine_ornithology_style_ref.docx
  pdf_document:
    keep_tex: yes
header-includes:
- \usepackage{lineno}
- \usepackage[labelformat=empty]{caption}
csl: emu-austral-ornithology.csl
bibliography: egg_temperature.bib
---

<!-- Title: all caps, centred

Authors: all caps, centred, each followed by a superscript number indicating affiliation and address. 

Author addresses: separate from names, italics, one address per line beginning with the superscript number corresponding to the author, e-mail address for corresponding author only 

Abstract: An abstract should be included. The abstract includes the centred heading "ABSTRACT" followed by the citation of the article in reference format, followed by text of abstract (maximum 300 words for submissions of >2000 words), and five to seven key words. Short submissions <2000 words should include an abstract of 100 words or fewer. Abstracts do not include tables, figures, or references. Authors may supply a translation of the abstract into another language, to be published after the English-language version. --> 
*^A^Department of Geography, University of Florida, Gainesville, FL 32611, USA (pboesu@gmail.com)*  
*^B^Emerging Pathogens Institute, University of Florida, Gainesville, FL 32610, USA*  
*^C^Department of Integrative Biology, University of South Florida, Tampa, FL 33610, USA*  
*^D^Department of Statistics, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061, USA*  
*^E^British Antarctic Survey, Natural Environment Research Council, Cambridge, CB3 0ET, UK*  

\linenumbers

## Abstract
Knowledge of thermal traits is essential for understanding and modelling physiological responses to environmental change. 
Egg temperatures are poorly studied in most tubenose species.
We employed a contactless infrared thermometer to measure egg and nest surface temperatures throughout the incubation period for four albatross species at Bird Island, South Georgia.
The observed mean warm-side temperature of 33.4°C for Wandering Albatross *Diomedea exulans* was similar to measurements obtained from this species using dummy eggs elsewhere.
Observed mean warm-side temperatures for Black-browed Albatross *Thalassarche melanophris*, Grey-headed Albatross *Thalassarche chrysostoma*, and Light-mantled Albatross *Phoebetria palpebrata*, reported here for the first time, were 30.7-31.5°C, which is lower than egg temperatures reported for most Procellariiformes.
Temperature gradients across viable eggs declined by up to 9°C during incubation, reflecting increased embryonic circulation and metabolic heat production. 
This suggests bioenergetic models should not assume constant egg temperatures during embryo development. 
Non-viable (addled) eggs could be identified by large temperature gradients in late incubation, indicating that infrared thermometry can be used to determine whether the embryo has died or the egg is infertile in monitoring and managed breeding (e.g. translocation) programmes.
Egg temperatures were correlated with ground temperatures, indicating that incubated eggs are vulnerable to environmental variability.


**Keywords:** Egg temperature, incubation, seabirds, *Thalassarche*, *Diomedea*

## Introduction
Avian incubation is inextricably linked to temperature, and therefore sensitive to a changing climate [@mainwaring2015nest]. 
Thermal conditions during incubation influence hatchling phenotypes [@durant2013ecological], with non-optimal temperatures resulting in embryo mortality or nestlings with lower fitness.
Changing environmental conditions have the potential to shape many aspects of avian biology, including through direct physiological impacts  [@oswald2012direct].
However, our understanding of seabird responses to direct impacts of global warming is incomplete [@gremillet2012heat]. 
Quantifying thermal traits is an essential precursor for better understanding and modelling seabird physiological responses to a changing environment [@konarzewski1998models;@teixeira2014new].

Egg temperature governs the metabolic rate of developing embryos [@mueller2015physiology], but the exact definition and determination of egg temperature is problematic.
The incubated egg is a complex living system, and incubation is a thermal mutualism, mediated by the physiology of both parent and embryo, and heat exchanges with the environment; 
as a result, different parts of the eggs can be at very different temperatures [@turner2002maintenance].