DOI: 10.5061/dryad.2jm63xt08
title: Data from: Accuracy and precision of an umbilical-based method for estimating birthdates of pre-weaned harbour seal pups

description: We evaluated the accuracy and precision of an umbilical-based method for
 fine-scale age and birthdate estimation in a wild population of harbour
 seal pups (Phoca vitulina) in the St. Lawrence Estuary, Quebec, Canada.
 The method consists of attributing umbilicus degeneration scores to
 estimate pup age in days. To assess its validity, we first constructed a
 score attribution test with field pictures of pup umbilical cords at
 various stages of degeneration. This test was completed by 8 observers,
 and we measured the accuracy and precision of the umbilicus degeneration
 score attribution. We then used data from 758 pups (captured between 1998
 to 2023) for which an umbilical degeneration score was assigned in the
 field to evaluate the efficiency of this score to estimate birthdate. We
 show that observers can accurately and precisely attribute umbilicus
 scores, and that this umbilical-based method can accurately
 estimate pup birthdates. Here are the two datasets used, as well as a
 README.md file which describe the data.
description: The data was collected by capturing wild habour seal pups in the
 St. Lawrence Estuary. We used data on the umbilicus degeneration scores in
 this study, from which we took pictures directly in the field. Those
 pictures were used to construct the picture test data set. 
description: # Data from: Accuracy and precision of an umbilical-based method for
 estimating birthdates of pre-weaned harbour seal pups
 [https://doi.org/10.5061/dryad.2jm63xt08](https://doi.org/10.5061/dryad.2jm63xt08) ## Description of the data and file structure The data was collected by capturing wild habour seal pups in the St. Lawrence Estuary. We used data on the umbilicus degeneration scores in this study, from which we took pictures directly in the field. Those pictures were used to construct the picture test data set.  ### Files and variables #### File: repetability\_test\_data\_anonyme.csv **Description:** This dataset was used to evaluate the accuracy and precision when attributing an umbilicus degeneration score. The data in this dataset comes from pictures of umbilicus cords taken on the field during the 2023 field season. We used 25 pictures and we had 8 different observers that did our picture test. ##### Variables * ID_photo: The individual identification of the photo, from 1 to 25. * obs: The umbilicus degeneration score given by specific observers.  * name: The identification of the observers (from 1 to 8). * terrain: The umbilicus degeneration score given on the field for the specific picture. #### File: bday\_anonym.csv **Description:** This dataset was used to assess the ability of the umbilical-based method to estimate individual birthdates. To do so, we compared our method with a growth-based back-calculation method that has previously been used in published studies for harbour seals. The dataset includes data from harbour seal pups from the St. Lawrence Estuary between 1998 and 2023.  ##### Variables * year: Year of the capture of the individual pups.  * bday: Birth date of individual pups from the umbilicus-based method, in Julian date starting May 1st of each year (a birth date of 25 would mean that the individual was born on May 25th of its respective year).  * bday_bc: Birth date of individual pups from the growth-based method, in Julian date starting May 1st of each year (a birth date of 25 would mean that the individual was born on May 25th of its respective year).  * first_UDS: The umbilicus degeneration score given on the field during the first capture of the specific individual.  * num_ID: Individual identification of pups.  #### File: duration\_pairs.csv **Description:** This dataset includes data from umbilicus degeneration scores of harbour seal pups from the St. Lawrence Estuary, between 1998 and 2023, especially the duration in number of days between two consecutive capture events which we recorded an umbilicus degeneration score between scores 1 and 4.  ##### Variables * year: Year of capture. * site: Site of capture (bic for Bic Island and metis for Métis area). * duration: The duration in number of days between two captures of an individual where we recorded an umbilicus degeneration score between scores 1 and 4.  * pairs: Pairs of umbilicus degeneration scores between scores 1 and 4. Example: 1_4 means that the specific individual had been captured with an umbilicus degeneration score of 1 and had an umbilicus degeneration score of 4 during a following capture.  * ID: Individual identification of pups.