Intrinsic and extrinsic factors drive ontogeny of early-life at-sea behaviour in a marine top predator

Matt I D Carter,David Thompson,Clint J Blight,Deborah J F Russell,Kimberley A Bennett,Philip J Hosegood,Clare B Embling

doi:10.1038/s41598-017-15859-8

Matt I D Carter, David Thompson + Show 5 more

Open Access

https://doi.org/10.1038/s41598-017-15859-8

Copy DOI

Abstract

Young animals must learn to forage effectively to survive the transition from parental provisioning to independent feeding. Rapid development of successful foraging strategies is particularly important for capital breeders that do not receive parental guidance after weaning. The intrinsic and extrinsic drivers of variation in ontogeny of foraging are poorly understood for many species. Grey seals (Halichoerus grypus) are typical capital breeders; pups are abandoned on the natal site after a brief suckling phase, and must develop foraging skills without external input. We collected location and dive data from recently-weaned grey seal pups from two regions of the United Kingdom (the North Sea and the Celtic and Irish Seas) using animal-borne telemetry devices during their first months of independence at sea. Dive duration, depth, bottom time, and benthic diving increased over the first 40 days. The shape and magnitude of changes differed between regions. Females consistently had longer bottom times, and in the Celtic and Irish Seas they used shallower water than males. Regional sex differences suggest that extrinsic factors, such as water depth, contribute to behavioural sexual segregation. We recommend that conservation strategies consider movements of young naïve animals in addition to those of adults to account for developmental behavioural changes.

Highlights

Transition from dependence on parental provisioning to independent feeding is a critical time in the life of all animal species that receive parental care
All pups remained within the limits of the continental shelf, but North Sea (NS) individuals had a much wider dispersal pattern, and several pups travelled along the shelf break (Fig. 1)
One male from the Isle of May travelled between the United Kingdom (UK) and Norway on multiple occasions, diving to the bottom of the Norwegian Trench (Fig. 1b; >200 m)

Summary

Introduction

Transition from dependence on parental provisioning to independent feeding is a critical time in the life of all animal species that receive parental care. Whilst some work has investigated foraging in grey seal juveniles (>12 months old) and young-of-the-year (YOY; 5 months old)[35,36], and others have studied pup behaviour on and around the colony[37,38], only Bennett et al.[24] have examined the ontogeny of at-sea behaviour in recently-weaned pups across their first months of nutritional independence. Oceanographic conditions and prey availability vary among regions, presenting different challenges for different subpopulations Together, these factors may confer regional differences in the ontogeny of diving behaviour and the development of successful foraging strategies for grey seal pups

Methods

Results

Conclusion