“Everything is interesting if you go into it deeply enough”
- Richard Phillips Feynman ForMemRS

Research summary

Overview

My research interests lie in quantifying the drivers of individual- and population-level animal movement, behaviour and energetics to predict the impact of anthropogenic disturbance and environmental change on animals. Also, to develop new tools and methods to study this, and thus to derive recommendations for policy and conservation management. I have a focus in particular on the study of marine megafauna but I am keen to apply my research skills across all taxa. My most recent work (towards my PhD thesis) has examined the movements and behaviour of grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) in tidally energetic environments, and their potential interactions with Marine Renewable Energy (MRE) – see my PhD abstract below. Some of my previous projects have investigated the foraging ecology of magellanic penguins (Spheniscus magellanicus) and imperial cormorants (Leucocarbo atriceps), and the diving behaviour of harbour seals. I am also interested in developing new methods for movement ecology - in particular, my research has investigated how we can best utilise biologging equipment to maximise its potential and efficiency whilst minimizing its impact, and implementation of advanced analytical models to analyse the data collected from these tags.

Seal movements in tidally energetic environments: New methods and ecological insights for management

PhD, Swansea University​
Kay 2020 (PhD Thesis)
With the increasing threats of climate change, there is an ever-pressing need to reduce fossil fuel emissions. Thus, recent years have seen a dramatic increase in the development of marine renewable energy (MRE) devices to exploit tidally energetic environments to generate green electricity, which however poses threats to apex marine predators, such as seals. Relatively little is known about how seals will be affected by MRE developments and how they operate in the tidally energetic environments that are targeted by these industries. This information is crucial for mitigating the risk of conflict between seals and MRE developments and informing species conservation management, and is also at the forefront of fundamental research in animal movement ecology. Here, using grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) as my study species, with data collected in the Celtic and the North Sea, I aim to understand and quantify how marine predators move in tidally energetic environments. To achieve this, I develop new approaches to quantify the spatio-temporal scales and patterns of movement, design new tags to track seals in fine-scale and minimise tag impact, and examine in fine detail the movement and behaviour of seals in response to tidal currents. My research suggests that the movements and behaviour of seals in tidally energetic environments are driven by a combination of measurable (and in some cases predictable) demographic and environmental factors, and that the conservation strategies developed to manage the interaction between individuals and populations with MRE devices must consider site-specific differences, and account for wide inter-individual variation, with consequences regarding sample size requirements. Further work is required to elucidate the full extent of variability of marine predator movements, and threats of MRE developments, fully embracing new tools, data sharing, and research frameworks to ensure that such efforts fit the needs of practitioners.​

Tidal drivers of harbour seal movement and behaviour

PhD, Swansea University
Kay et al., ​In Prep
Marine predators are known to use tidally energetic areas for important behaviours, such as foraging and transiting, however an understanding of how they respond to changes in tidal conditions is limited. This information is important given the concerns regarding the impact of MRE devices, such as collision risk. This research combines the use of GPS and dive data collected from wild harbour seals, with high-resolution tidal current information, in an advanced hidden Markov modelling (HMM) framework, to investigate how changing tidal conditions influence the movements and behaviour of harbour seals (Phoca vitulina). This work offers novel insights into the optimising strategies that marine predators employ in energetically challenging environments, providing important information for their conservation management.

Optimising the use of biologging technology

This work reviews how researchers can optimise the use of animal tracking (biologging) tags to tackle key questions in the field of movement ecology, including by (i) using multi-sensor approaches in new tag deployments, (ii) sharing and utilising already existing datasets, (iii) establishing interdisciplinary collaborations, and (iv) appropriately matching the data obtained from specific sensors to statistical models best suited to analyse them. This information is synthesized into an Integrated Biologging Framework (IBF).

Natal dispersal of grey seal pups

PhD, Swansea University
Kay et al., In Prep
Despite their biological importance, little is known of the early movements of juveniles of many taxa. This lack of knowledge is particularly pertinent to marine predators, such as grey seal pups (Halichoerus grypus). Understanding this is crucial because young individuals are particularly vulnerable and naive, and susceptible to incidental mortality. In this research I quantify natal dispersal in grey seal pups and reveal drivers of displacement, using this to predict their  spatio-temporal distribution. I focus on pups from Wales, including the largest breeding colony in the south of the UK (Pembrokeshire). My work shows that individuals cover vast ranges (up to 1000 km) during their first few months at sea and that displacement distance and propensity is driven by density-dependence and sex-specific responses to local weather conditions. In a novel approach, I implement the squared displacement modelling method to both individual- and population-level data to quantify the displacement of seals over time, revealing large inter-individual variation, and that seals displace from their natal colonies in either a diffusive or dispersal-like fashion. Through this work I also derive recommendations for the sample sizes and recording duration required to appropriately quantify grey seal pup dispersal. This research can provide evidence towards seal conservation management strategies, demonstrates the value of applying new methods to old data, and can inform best practice regarding the tagging procedures of wild grey seal pups.

Spatio-temporal overlap risk of grey seal pups with MRE sites

PhD, Swansea University
Kay et al., In Prep
In having derived displacement curves for grey seal pups over time, I sought to use these to predict the potential spatio-temporal overlap risk of dispersing pups with nearby MRE sites. To do this, I combined the predictive displacement kernels with daily pup count data to derive a time window of maximum spatio-temporal overlap risk. This can inform MRE industries to devise strategies to minimise the risk of spatio-temporal overlap between grey seal pups and MRE devices, and offers a new tool for determining this risk.

Developing remote-release tags to track wild pinnipeds

PhD, Swansea University
Kay et al., In Prep
The use of biologging tags has revolutionised the study of pinniped ecology for over six decades. However, commercial tags are often limited in their functionality, costs are high, and researchers are generally restricted in their ability to collect high-resolution data (such as relating to fine-scale movement and energetics). Furthermore, recovering archival tags from the marine environment is inherently difficult, and so far tags for pinnipeds have not demonstrated consistently reliable options for recovery. In this work I developed a customizable prototype biologging tag for tracking the fine-scale, high-resolution 3D movements of wild pinnipeds. This tag incorporates multiple devices; a Fastloc-GPS, a triaxial inertial movement sensor, a modified pressure sensor, a transmission unit to aid recovery (ARGOS SPOT or VHF tag), and a Galvanic Timed Release (GTR). This tag is approximately 3 times less expensive than a commercial alternative with comparable functionality. I deployed tags on free-ranging harbour and grey seals, collecting high-resolution movement data at 40 Hz for up to 14 days. This tag offers the potential for a fully customizable and affordable option for tagging wild pinniped species with a remote-release mechanism that combines multiple biologging devices to provide high functionality and versatility. The lessons learnt from the development of this tag can aid future researchers and contribute more broadly to the design of biologging tags for free-ranging pinnipeds.

Designing hydrodynamic animal tracking devices to minimise their impact

Tags deployed on marine predators will incur a drag load that can be substantial. In order to mitigate this, tags need to be designed to be streamlined. In this research, I worked together with aerospace engineers and utilised computational fluid dynamics (CFD) modelling to optimise the design and positioning of biologgers on marine animals, using the grey seal (Halichoerus grypus) as a model species. By comparing a conventional vs. a streamlined tag, I show that the former can induce up to 22 % larger drag for a swimming seal. The CFD simulation approach can be used to optimise tag design to reduce drag. I also provide a step-by-step guide to facilitate implementation of CFD in biologging tag design.

Consumptive competition in colonial pinnipeds

MSc by Research, Swansea University
Wilson et al., 2014 (PeerJ)
Colonial pinnipeds may be subject to substantial consumptive competition because of their proximity to conspecifics and shared use of resources, and this is particularly acute in central place foragers. Using the harbour seal (Phoca vitulina) as a study species, this research examines the possible mechanisms for reducing foraging competition by examining the diving behaviour of individuals in the Wadden Sea. This findings suggests that males may have higher overall swim speeds, which would increase higher oxygen consumption, and may explain the shorter dive durations compared to females. Intersex variation in swim speed alone is predicted to lead to fundamental differences in the time use of 3D space, which may help reduce consumptive competition in harbour seals and other colonial pinnipeds.

Movement strategies of harbour seals

MSc by Research, Swansea University
Kay 2015 (MSc Thesis)
In this work I investigated the movement decisions made by harbour seals (Phoca vitulina) during central-place foraging trips. Seals displayed high fidelity to haul-out sites with very few trips not returning to the central place. Foraging trips showed two distinct characteristics: (1) direct transit sections at relatively constant speeds from the central place (1 - 1.4 ms-1; in line with minimum cost of transport estimates for harbour seals) and (2) tortuous, central sections with significantly slower speeds (0 - 0.2 ms-1), reflecting area-restricted search. I proposed a novel framework for understanding the energetics of movement patterns within central-place foraging trips; that of "implied costs". Specifically, the energetic costs of travel are not only the absolute costs of transport, but also the costs for the animal to return towards their start point to make good the outward (or partially outward) trajectory. In other words, the chosen travel direction of travel determines the final energetic costs of movement, such that the angle of deviation from the start point is linearly associated with cost. Of course, the movement choices made by seals whilst foraging will fundamentally be associated with the potential and realized profitability of the prey patch that they are exploiting, and the effect of "Ashmole's halo" is closely linked to this. Nevertheless, central place foragers should mitigate additional (and especially unrewarded) energetic expenditure wherever possible. Accordingly, the overall movement of seals during bouts of ARS was radial (i.e. parallel to the shore) which served to minimise the distance travelled from the central place during foraging, and therefore minimise future energetic costs. ​

​Diving behaviour of harbour seals

MSc by Research, Swansea University
Kay 2015 (MSc Thesis)
This work examined how harbour seals (Phoca vitulina) modulated their diving behaviour in line with optimal foraging strategies. Bimodality was apparent with two dive types observed, benthic and non-benthic, displaying clear differences in depth usage and dive parameters. Seals displayed marked variability between dives and modulated dive parameters in accordance with optimal foraging theory. Specifically, bottom time was maximised by increasing vertical velocity on deeper dives. Benthic dives displayed longer bottom durations and higher dive efficiencies than non-benthic ones. Short post-dive surface intervals of ≤100 s followed 90% of dives, suggesting that most dives conducted were aerobic.

Optimal foraging strategies of Magellanic penguins

BSc (Hons), Swansea University
Kay 2013 (BSc Dissertation)
In my undergraduate research I examined the optimal foraging strategies of magellanic penguins (Spheniscus magellanicus). Specifically, I investigated how energetic expenditure (measured via Overall Dynamic Body Acceleration; ODBA) scaled with the number of prey caught during dives (assessed using 'wiggles' i.e. serial points of inflection; SPI), and consequently how this relates to the duration of the post-dive surface interval (PDSI) recovery period and dive efficiency.

Digitising historical data

PhD, Swansea University
Kay et al., ​In Prep
Understanding the size, movement and survival of wild animal populations is crucial for conservation management. In long-lived species information on young individuals is relatively limited, despite them representing a substantial proportion of the population. In 2016 a historical ringing record of grey seal pups was discovered, detailing the movements of over 1300 individual seals between 1954-1972. These data, retrieved from NRW archives, were originally recorded in hand-written format but in this project I digitised them and made them accessible to the scientific community. This dataset provides a large sample size of grey seal pups from Wales and complements other marking efforts undertaken across the UK during the same period, as well as subsequent efforts in the following decades. These data are a valuable historical resource for studying seals in the Irish and Celtic Seas and can be used for various life history and movement-related analyses, such as studies investigating phenology, movement, population dynamics, and distribution.