Individual specialization in a generalist apex predator: The leopard seal

Apex predators are typically considered dietary generalists, often masking individual variability. However, individual specialization—consistent differences in diet and foraging strategies among individuals— is common in apex predators. In some species, only a few specialized individuals can significantly impact prey populations. Leopard seals (Hydrurga leptonyx) are apex predators important to the structure and function of the Southern Ocean ecosystem. Leopard seals are broadly described as generalists, but little is known about their trophic ecology at the population or individual level. We analyzed δ13C and δ15N profiles in whiskers (n=46) from 34 leopard seals from an important aggregation in the Western Antarctic Peninsula to assess population and individual trophic variation. We also evaluated individual consistency across years using repeat samples from 7 seals collected over 2-10 years. We compared population and individual isotopic niche space and explored drivers of intra..., Sample Collection
Leopard seals were sampled between January and May from 2013 to 2023 at the U.S. Antarctic Marine Living Resources (AMLR) Program ecological monitoring site at Cape Shirreff, Livingston Island in the WAP. Leopard seals were sedated (Pussini and Goebel, 2015; Krause et al., 2016) to allow for the collection of morphometric data (standard length [cm], girths, and mass [kg]), life history traits (sex, age class), and whiskers. Whiskers were collected from 34 leopard seals (28 females, 6 males). Seven females were opportunistically resampled without a full capture (i.e., morphometric data were not collected) 1-3 times after their first handling, resulting in 12 additional whisker samples. In total, we analyzed 46 whiskers (40 females, 6 males). A subset of these whiskers (n=18 from field seasons 2018 and 2019) were previously analyzed by (Charapata et al., 2023).
Stable Isotope Analysis (SIA)
Whiskers were wiped with 1:1 ethanol:methanol solvent, sonicated for 30 mins in d..., , # Individual specialization in a generalist apex predator: The leopard seal

[https://doi.org/10.5061/dryad.f4qrfj75k](https://doi.org/10.5061/dryad.f4qrfj75k)

## Description of the data and file structure

Data for: Individual Specialization in a Generalist Apex Predator: The Leopard Seal

The data provided are the raw final bulk stable isotope data (δ¹⁵N and δ¹³C) profiles from whiskers (n = 46) collected from 34 individual leopard seals. All additional metadata and relevant information are included in the manuscript.

**Description of the Data and file structure**

The spreadsheet contains the following columns:

* Seal.ID: Identifies individual seals. If whiskers were collected from the same seal in different years (repeat samples), the Seal.ID includes a suffix to indicate the year of collection.

For example, a whisker collected from seal 397 in year 1 is labeled as 397.

For subsequent years, the same seal's ID is updated incrementally: 397.1 for year 2, 397.2 for year 3, and 39...,