DOI: 10.5061/dryad.mkkwh71bh
title: Data from: Spatiotemporal variation in marine mammal antipredator behaviors resulting from a predation pinch point

description: Predator-prey relationships are fundamental aspects of ecological systems
 that determine the behavior and distribution of animals across time and
 space. Variation in predation risk can be used to explore when and why
 individuals perform antipredator behaviors. In marine environments, it is
 difficult to observe predation and antipredator behaviors. Fortunately,
 biologgers have long been used to study the distribution and dive
 behaviors of northern elephant seals (Mirounga angustirostris) on their
 twice-yearly foraging trips. Here, we analyzed the horizontal and vertical
 movements of 353 adult female seals across 17 years to investigate how
 they move through a “predation pinch point” - an area where predators and
 prey co-occur due to habitat features. Specifically, we explored the diel
 timing of departure from and arrival to the colony and spatial
 concentrations in benthic diving (diving close to/along the seafloor).
 Benthic diving and temporal concentrations in movement to and from the
 colony may serve antipredator functions, such as minimizing detection and
 ambush by predators. We found that only the timing of departure from, and
 not arrival to, the colony showed any significant temporal pattern. Seals
 tended to depart during the late afternoon or at night but arrived
 throughout the day. Spatially, there were consistent patterns of benthic
 dives during the first and final parts of their trips as seals crossed the
 continental shelf. By combining dive, location, bathymetry, and predator
 data we were able to identify how seals modified behaviors that likely
 help them avoid predators. These findings illustrate how animals respond
 to varying levels of predation risk and can be used to develop more
 precise dynamic landscapes of fear.
description: # Data from: Spatiotemporal variation in marine mammal antipredator
 behaviors resulting from a predation pinch point Dataset DOI:
 [10.5061/dryad.mkkwh71bh](10.5061/dryad.mkkwh71bh) Publication
 DOI: [https://doi.org/10.1002/ece3.72841](https://doi.org/10.1002/ece3.72841) ## Description of the data and file structure ### Summary This repository contains the code used to create figures in [Hale et al., 2026](https://onlinelibrary.wiley.com/doi/10.1002/ece3.72841) The script 'FiguresForMS_11_21_2025_RSB.qmd" contains the tools/functions necessary to recreate the figures in the associated manuscript. Preliminary steps [in 'data_wrangling_RSB_2025_10_29.qmd'] are required to ensure that the data is processed correctly and that bathymetry and predator data are included. ## Files and variables ### Data File Details #### Details for: TV4_DiveStatType_CMH_2025_07_14.txt Description: a .txt file containing raw data that was processed for analysis. This file can be opened in any plain text editor. Data are separated by commas. Variables within 'TV4_DiveStatType_CMH_2025_07_14.txt': * id = seal identification code (a seven-digit number [e.g., 2004001] where the first two digits designate the species [20 is northern elephant seal], digits 3-4 indicate the year [e.g., 04 is 2004], and digits 5–7 are the deployment serial number [001 is the first deployment for a given year and species]) * DiveNumber = count of the dive * JulDate = Julian date; extracted from MATLAB and converted to POSITXct time using the function in 'data_wrangling_RSB 2025_10_29.qmd' * Maxdepth = maximum depth reached during the associated DiveNumber (i.e., dive 1 was 36 meters, dive 2 was 48.5 meters, etc.); measured in meters * Dduration = dive duration for the associated dive (i.e., dive 1 was 624 seconds, dive 2 was 576 seconds, etc.); measured in seconds * Bottime = bottom time for the associated dive; measured in seconds * DescRate, AscRate = descent and ascent rates for the associated dive; measured in m/s * PDI (post-dive interval) = time spend at the surface following the prior dive (e.g., dive 1 was 624 seconds and the post-dive interval was 64 seconds); measured in seconds * DateTime = date and time of associated dive; DD-M-YYYY, HH:MM:SS * Lat = latitude of associated dive * Long = longitude of associated dive * Lat_se_km, Lon_se_km = standard error associated with latitude/longitude of associated dive; measured in km * SolarEl = angle of solar elevation during the associated dive; units are degrees * Lon360 = converts longitude values from -180;180 to 0:360 (see [https://dankelley.github.io/oce/reference/lon360.html](https://dankelley.github.io/oce/reference/lon360.html)) * DiveTypeName = name type of the associated dive; determined as described in the manuscript #### Details for: data_wrangling_RSB_2025_10_29.qmd Description: a quarto markdown file containing the tools/functions necessary to recreate the figures in the associated manuscript. This file can be opened using RStudio (ver. 2023.06). Variables within 'data_wrangling_RSB_2025_10_29.qmd': * TV4_DiveStatType_CMH_2025_07_14.txt = described above * shark_area.kml = described in detail below * orca_area.kml = described in detail below * dist2land_tweak.R = described in detail below #### Details for: FiguresForMS_11_21_2025_RSB.qmd Description: a quarto markdown file containing the tools/functions necessary to recreate the figures in the associated manuscript. This file can be opened using RStudio (ver. 2023.06). Variables within 'FiguresForMS_11_21_2025_RSB.qmd': * data_dive_RSB_2025_10_29.rds = described in detail below #### Details for: *_iknos_raw_data.csv Description: .csv files containing the raw time-depth records for the four seals included in Figure 1. Files are included separately as: 2008044_iknos_raw_data.csv, 2009040_iknos_raw_data.csv, 2011014_iknos_raw_data.csv, and 2014019_iknos_raw_data.csv. Variables within '*_iknos_raw_data.csv': * CorrectedDepth = corrected depth of the recorded dive (for more information about this please see Costa et al., 2024); in meters * time = time the dive took place; must be converted to POSIX time (there is a function to do this in 'FiguresForMS_11_21_2025_RSB.qmd') * depth = depth of the recorded dive; in meters #### Details for: data_dive_RSB_2025_10_29.rds Description: an RSD file that is the output of 'data_wrangling_RSB_2025_10_29.qmd'. This file can be opened in RStudio (ver. 2023.06) using the readRDS() function. Variables within 'data_dive_RSB_2025_10_29.rds': * id = seal identification code (a seven-digit number [e.g., 2004001] where the first two digits designate the species [20 is northern elephant seal], digits 3-4 indicate the year [e.g., 04 is 2004], and digits 5–7 are the deployment serial number [001 is the first deployment for a given year and species]) * DiveNumber = count of the dive * JulDate = Julian date; extracted from MATLAB and converted to POSITXct time using the function in 'data_wrangling_RSB 2025_10_29.qmd' * Maxdepth = maximum depth reached during the associated DiveNumber (i.e., dive 1 was 36 meters, dive 2 was 48.5 meters, etc.); measured in meters * Dduration = dive duration for the associated dive (i.e., dive 1 was 624 seconds, dive 2 was 576 seconds, etc.); measured in seconds * Bottime = bottom time for the associated dive; measured in seconds * DescRate, AscRate = descent and ascent rates for the associated dive; measured in m/s * PDI (post-dive interval) = time spend at the surface following the prior dive (e.g., dive 1 was 624 seconds and the post-dive interval was 64 seconds); measured in seconds * DateTime = date and time of associated dive; YYYY-MM-DD, HH:MM:SS * Lat = latitude of associated dive * Long = longitude of associated dive * Lat_se_km, Lon_se_km = standard error associated with latitude/longitude of associated dive; measured in km * SolarEl = angle of solar elevation during the associated dive; units are degrees * Lon360 = converts longitude values from -180;180 to 0:360 (see [https://dankelley.github.io/oce/reference/lon360.html](https://dankelley.github.io/oce/reference/lon360.html)) * DiveTypeName = name type of the associated dive; determined as described in the manuscript * BirthYear = year in which the associated seal was born * SatTagType = type of satellite tag used during the deployment; described in the methods * GPSRows = used to determine if GPS was used as well; described in methods * DepartLoc, ArriveLoc = departure and arrival locations; has been pre-filtered to only include ANNU (Año Nuevo) * DepartCalcMass = mass at departure for each seal; in kilograms * trip = foraging trip type; either Post Breeding or Post Molting  * bathy = bathymetry measurement for the associated dive * dist_dep = distance from Año Nuevo during associated dive; measured in km (used for Figure 5B) * shark_area, orca_area, shark_and_orca, shark_or_orca = presence or absence of seals in associated area for each associated dive; 1 = presence and 0 = absence #### Details for: TV4_SealInfo_CMH_2025_07_14.txt Description: a .txt file with information used in 'FiguresForMS_11_21_2025_RSB.qmd' and 'data_wrangling_RSB_2025_10_29.qmd'. This file can be opened in any plain text editor. Data are separated by commas. Variables within 'TV4_SealInfo_CMH_2025_07_14.txt': * id = seal identification code (a seven-digit number [e.g., 2004001] where the first two digits designate the species [20 is northern elephant seal], digits 3-4 indicate the year [e.g., 04 is 2004], and digits 5–7 are the deployment serial number [001 is the first deployment for a given year and species]) * BirthYear = year the seal was born * SatTagType = type of tag the seal was equipped with; described in methods * GPSRows; used to determine if the satellite tag used Argos + GPS or only Argos; described in methods * DepartLoc, ArriveLoc = departure and arrival locations; is later filtered to only include ANNU (Año Nuevo) * DepartCalcMass = mass at departure for each seal; in kilograms * trip = foraging trip type; either Post Breeding or Post Molting #### Details for: R_Table.png Description: a .png file with packages using in R; pulled from the grateful package #### Details for: dist2land_tweak Description: an R script file with code to adjust the data for Figure 5B in the associated publication; used in 'data_wrangling_RSB 2025_10_29.qmd'. This file can be opened using RStudio (ver. 2023.06). #### Details for: orca_area.kml Description: a .kml file (extracted from Google Earth) with the distribution of mammal eating orca's (adapted from [Jorgensen et al., 2019](https://www.nature.com/articles/s41598-019-39356-2)); used in 'data_wrangling_RSB 2025_10_29.qmd'. This file can be opened in Google Earth Pro (ver. 7.6.3) or by using [https://kmzview.com/.](https://kmzview.com/) #### Details for: shark_area.kml Description: a .kml file (extracted from Google Earth) with the distribution of white sharks (adapted from [Jorgensen et al., 2019](https://www.nature.com/articles/s41598-019-39356-2)); used in 'data_wrangling_RSB 2025_10_29.qmd'. This file can be opened in Google Earth Pro (ver. 7.6.3) or by using [https://kmzview.com/.](https://kmzview.com/) ## Code/software Data processing methods are well described in [Costa et al., 2024](https://www.nature.com/articles/s41597-024-04084-4). Secondary processing and figure creation was done in RStudio (ver. 2023.06). The script 'FiguresForMS_11_21_2025_RSB.qmd' contains the tools/functions necessary to recreate the figures in the associated manuscript. Please note that preliminary steps (in 'data_wrangling_RSB_2025_10_29.qmd') are required to ensure that the data is processed correctly and that bathymetry and predator data are included. A table that includes the R packages is included in the files (R_Table.png). ## Access information Data was derived from the following sources: * Costa, D. P., Holser, R. R., Keates, T. R., Adachi, T., Beltran, R. S., Champagne, C. D., ... & Yoda, K. (2024). Two decades of three-dimensional movement data from adult female northern elephant seals. *Scientific Data*, *11*(1), 1357. We gratefully acknowledge the work the University of California Santa Cruz, Sonoma State University, and Tagging of Pacific Predators Program teams did to produce this rich dataset. Full funding information for the dataset can be found in Costa *et al.,* 2024