1. BLACK GUILLEMOT FORAGING ECOLOGY IN RELATION TO MARINE RENEWABLE ENERGY
Daniel Johnston1, Robert W. Furness2, Alex Robbins3, Mark Taggart1, Elizabeth A. Masden1
Figure 1. GPS tracks of black guillemots from Stroma (a) 2016 and (b)2017. Individual variability was frequently seen between tagged birds. a b
Figure 2. Foraging behaviour states (yellow points) as produced by HMMs (a) 2016 and (b) Individuals foraged primarily in Orkney waters, and the tidally active areas surrounding Stroma.
Figure 4. Foraging (yellow), Meygen (red), and Inner Sound (green). The tidal variables within the Inner Sound were isolated for analysis.
Figure x.Location of Stroma and tidal lease areas. .
Figure.3 Foraging (yellow) in relation to Meygen (red) and the Inner Sound (green)- the tidally active area of interest.
1 Environmental Research Institute, North Highland College, University of the Highlands and Islands, Thurso, KW14 7EE
2 MacArthur Green Ltd, 95 Woodside Road, Glasgow, G20 6NT, UK
3 Scottish Natural Heritage, Great Glen House, Leachkin Road, Inverness, IV3 8NW 
INTRODUCTION
In Scotland, black guillemots Cepphus grylle have an inshore, demersal, piscivorous diet, and associate with tidal currents while undertaking foraging dives1,2. These behaviours make them potentially vulnerable to planned tidal-stream marine renewable energy developments3. They may dive up to 40m and individuals have also been recorded at depths which tidal turbines will likely operate (8-26m)4. The potential effects of tidal turbines may include collision risk, habitat modification, and changes in prey distribution. This study investigates the extent of spatial overlap between foraging black guillemots and the Meygen tidal lease within the Inner Sound of the Pentland Firth, where 3 tidal turbines were constructed in winter 2016/2017.
METHODS
In June and July 2016/2017, black guillemots were studied on the island of Stroma adjacent to Meygen tidal lease area (Fig. 3,4). 13 adults were GPS tracked on Stroma (Tab. 1) using PathTrack nanoFixGEO tags. Hidden Markov modelling (“moveHMM” R package) was used to define 2 behavioural states within the tracks: “Foraging” and “Transiting”. Foraging occurring within the Inner Sound (south of Stroma) was compared to bathymetry and tidal variables -velocity and Turbulent Kinetic Energy Dissipation (TKED) (Fig 5,6 on the next slide). Flow velocity (m/s), and TKED (WATT/KG) – the measurement of turbulent flow by the kinetic energy per unit mass- were generated through TELEMAC predictive models.
RESULTS
REFERENCES: (1) Robbins, A. (2012). Analysis of Bird and Marine Mammal Data for Fall of Warness Tidal Test Site, Orkney. Scottish Natural Heritage Commissioned Report No (2) Wade, H. (2015) Investigating the potential effects of marine renewable energy developments on seabirds. PhD Thesis. (3) Furness, R. W., Wade, H. M., Robbins, A. M., & Masden, E. A. (2012). Assessing the sensitivity of seabird populations to adverse effects from tidal stream turbines and wave energy devices. ICES Journal of Marine Science: Journal du Conseil, 69(8), (4) Masden, E. A., Foster, S., & Jackson, A. C. (2013). Diving behaviour of Black Guillemots Cepphus grylle in the Pentland Firth, UK: potential for interactions with tidal stream energy developments. Bird Study, 60(4),
Year
Tags
Max period (h:m)
Max Dist (km)
Mean Dist (km)
2016 8
59:55 ± 20:08
26.49
4.23 ± 4.51
2017 5
121:17 ± 26:17
25.16
2.99 ± 7.14
Table 1. Tag deployment results for Stroma 2016 and Fewer tags were deployed in the 2017 field season, however a longer time series of data was obtained.

2. a b a b INNER SOUND TIDAL CHARACTERISTICS
Spatial covariates of TKED (Fig. 5), flow velocity (Fig. 6) and bathymetry (Fig. 5/6 b) were compared to the foraging locations of black guillemots and the Meygen tidal lease area. Similarities are seen in the TKEDs associated with Meygen and foraging (Fig.7). Parts of Meygen are situated in faster flows than used by black guillemots (Fig.8), although there is some overlap. The Meygen area is primarily situated in deeper depths than the foraging locations (Fig.9).
SUMMARY
While there is a degree of overlap between Meygen and foraging individuals in relation to flow velocity and TKED, this overlap is spatially minimal potentially due to their associated depth (Fig. 5/6). Meygen primarily corresponds with deeper areas (mean: -32m) than the foraging locations (mean: -22m). However Meygen’s depths are not outwith the diving capabilities of black guillemots4. As currents slow in some areas with the introduction of tidal turbines, these deeper areas may become energetically suitable for foraging.
Long foraging tracks towards Orkney also display that birds may overlap with tidal lease areas further from their breeding sites than previously thought (Fig. 1).
In the future, temporal aspects such as tidal phase and photoperiod will need to be related to foraging times. Further spatial aspects such as benthic habitat and prey will also be taken into account.
Figure 5. TKED within the Inner Sound compared spatially (a), and non-spatially in relation to bathymetrical depth (b).
Figure 7. Turbulent kinetic energy dissipation comparison between the Inner Sound, Meygen, and black guillemot foraging locations for 2016 and
Figure 8. Flow velocity comparison between the Inner Sound, Meygen, and black guillemot foraging locations for 2016 and 2017.
Figure 9. Bathymetry comparison between the Inner Sound, Meygen, and black guillemot foraging locations for 2016 and 2017. a b
Figure 6. Flow velocity within the Inner Sound compared spatially (a), and non-spatially in relation to bathymetrical depth (b).
ACKNOWLEDGEMENTS: Field work on Stroma would have not been possible without the help Dr. Nina O’Hanlon, and logistical help from Dr. Jason McIlveny. Field work carried out on North Ronaldsay (not included on this poster) was part funded by a MASTS Small Grant, and was greatly aided by the staff and volunteers of the North Ronaldsay Bird Observatory. Tidal data was generated by Dr. Jason McIlveny.