DOI: 10.5061/dryad.9kd51c5x7
title: Data and code from: Sea ice perturbation and mass starvation of Thick-billed Murres

description: During spring 2022, thousands of Thick-billed Murres (Uria lomvia) died on
 the southern Labrador and northeastern Newfoundland coasts. Location and
 timing of the event were compiled from public sources, including social
 media and institutions. Some retained carcasses were dissected and
 compared to healthy birds. The rapid-onset, five-week event lasted from
 March 18 to April 25, 2022, emanating from an impact site in southern
 Labrador. Extreme winds compacted and reduced sea ice area, which exposed
 sub-zero water temperatures and limited feeding options. Dissections were
 performed to determine body condition and demographics of birds affected.
 Neither sex nor age was associated with mortality, and a subset of
 carcasses tested negative for influenza A. Carcass masses averaged 65.5 %
 of the body mass of healthy birds, indicative of a threshold for stage III
 starvation (protein catabolism). Photographs and measurements showed
 significant pectoral muscle wasting, and pectoral mass was less than that
 of healthy birds. The probable cause of the die-off is starvation
 accelerated by a rapid drop in water temperature and limited foraging
 options driven by a sea-ice perturbation. Ocean-climatic variability and
 extreme events are expected to increase, posing challenges for polar
 seabirds.
description: # Data and code from: Sea ice perturbation and mass starvation of
 Thick-billed Murres Dataset DOI:
 [10.5061/dryad.9kd51c5x7](https://doi.org/10.5061/dryad.9kd51c5x7) ##
 Description of the data and file structure Sightings of stranded and
 deceased seabirds were compiled from social media, public reports, and
 counts and reviews from community organizations. Die-off carcasses were
 collected from multiple locations and frozen for further study. Both these
 birds and birds obtained from hunters were dissected. They were weighed,
 sexed, and external and internal measurements were taken.  ### Files and
 variables #### File: tbmuhonours.Rproj **Description:** Overarching
 project file to run code in R #### File: tbmumap.Rmd
 **Description:** Markdown file that organizes and tidies the compiled
 public reports of strandings and shows maps and graphs of where and when
 birds were found #### File: tbmustats.Rmd **Description:** Markdown file
 that organizes and analyzes results of bird necropsies to compare healthy
 birds to birds killed in the die-off #### File:
 Murre_Stranding_Locations.csv **Description:** Compiled public reports of
 strandings from the 2022-2023 mass mortality event ##### Variables * Date:
 M/D/Y * Species: Species of bird observed (if known) * TBMU: Thick-billed
 Murre * COMU: Common Murre * NA: for unknown or unspecified species *
 Place: Community Name * Latitude: Degrees * Longitude: Degrees * Total:
 Total number of birds witnessed * Live: Number of living birds * Dead:
 Number of dead birds * Observer: Name of person who reported the birds.
 Left blank if unknown * Source: Name of place where report was received.
 ex. Personal Communication, Facebook, eBird. * Other/Notes: Description of
 sighting #### File: tbmu_necrospies_data.csv **Description:** Compiled
 results from dissections ##### Variables * Specimen: Number denoting order
 of dissection * Identifier: Tag from collector describing when and where
 bird was recovered. Some birds had no tag/different tags. For birds shot
 by hunters, identifier is Source (Twillingate or Noah) Control and Number
 * Location: Community where bird was found * Date of Retrieval: Used for
 control only  * Date of Dissection: Day-Month (dissections completed
 between October 2023- February 2024 * Conrol or Wreck: (Misspelled Control
 in the column name) 'Starved' is from the wreck, 'control
 is hunter-obtained birds * Partial or Intact: 'Partial' denotes
 a bird that was previously partially dissected. 'Intact' means
 the bird had not been touched since being picked up. 'Control'
 means hunter caught birds * Sex Necropsy: Sex determined by visual
 observation of gonads upon dissection * Sex Feather : Sex determined by
 feather testing at McGill lab * Sex: Overall sex, since both methods were
 not used on all birds * Plumage: Breeding. Because of time of year, all
 birds were in nonbreeding plumage * Wing Length : Centimeters * Mass:
 Grams * Culmen: length of beak from the top, beginning at feathers to the
 tip. millimeters * Sternum Length: length of keel bone in cm *
 Supraorbital Ridge: Determination if an individual was juvenile or adult
 by the presence/absence of a brow ridge * Lipid Index: Level of body fat *
 Pectoral Mass: Mass removed left pectoral muscle * Total Breast Weight:
 weight of both pectorals and breastbone together * Notes: anything unusual
 about dissection * Dissector: Name of dissector * Keel: Projection of keel
 over pectoral muscles at its highest point using a ruler * Keel Sternum
 Ratio: projection of keel divided by sternum length ## Code/software
 Rstudio running R version 4.2.3 (R Core Team, Dec 1 2023) using packages
 tidyverse (Wickham et al., 2019), doBy (Hojsgaard & Halekoh, 2023),
 viridis (Garnier et al., 2024), and patchwork (Pedersen, 2024).\