Lauren clegg

Lauren Clegg

Differences in Behaviour of Halichoerus grypus at Two Sites in Cornwall

Lauren Clegg FdSc Marine Science, Cornwall College, Falmouth Marine School, Falmouth TR11 3QS

This study investigated the ethology of Halichoerus grypus at two similar tidal offshore haul outs, with the main difference of exposure to disturbance. The study was to compare the behaviour of Halichoerus grypus at each site, to conclude whether a higher exposure to disturbance will cause a difference in behaviour. Land based surveys took place over a six week period, finally gathering 48 hours of observational data. More seals were recorded at Gwennap Head; therefore more varying behaviours were recorded. Although the data did not deem sufficient enough statistically, the Halichoerus grypus surveyed within the Fal, have not yet been recorded for behavioural interest.

Therefore this study is a baseline study to be continued by Falmouth Marine School students, hopefully over many years to come. These studies can aid the spread of knowledge and continuous protection of Grey seals around the Cornish coast.

Key words: ethology, Halichoerus grypus, haul out, disturbance, behaviour.

___________________________________________________________________________ INTRODUCTION Halichoerus grypus are the most abundant of carnivorous marine mammal sighted in the South West of England. (Leeney et al. 2010) The UK coastline is home to approximately 45% of the total worldwide population (Ibid) with a small percentage of the population of Great Britain living in numerous colonies around the Cornish coasts. (Summers, 1974) An estimation of 0.5% of the worldwide Halichoerus grypus population can be found around the Coast of Cornwall and the Isles of Scilly. Pup census are undertaken to estimate the annual population increase around the Cornish coastline. (CSG, 2010) Common seals, Phoca vitulina are rare around the South West of England, but have been known to visit the Cornish Coasts. (CSG, 2009) Grey seals in the South West UK usually haul out on rocky outcrops or sandy beaches in

groups, usually lying fairly close together.

(SMRU, 2010) Haul outs are used by seals as areas to rest, moult, digest their recent meal, mate and give birth. (Lewis, 2006) Grey seals, Halichoerus grypus are a highly protected species, (Strong et al. 2005) having once been listed as threatened due to over exploitation; however, fortunately the Grey seals are no longer threatened. (IUCN Redlist, 2010) Halichoerus grypus are protected under the Protection of Seals act 1970 and the European Union’s Habitats Directive (Council of the European Communities, 1992) however there are still many threats towards Grey seals in this region. (Leeney et al. 2010) Areas around the Cornish coast that are Sites of Special Scientific Interest (SSSIs) and Special Areas of Conservation (SACs) where Grey seals are found are usually designated due to the presence of Halichoerus grypus. (Kiely et al., 2000) Where Halichoerus grypus are listed as a feature within an Site of Special Scientific

Lauren Clegg Interest, protection of the creatures is held through the Wildlife and Countryside Act. Grey seals are also protected under Annex II and Annex V of the EC Habitats Directive 1992 (NE, 2010) and Appendix III species under the Bern convention (WiSe, 2008) Human and seal interaction includes the threat of net entanglement. Seals are naturally very curious creatures and have been seen to approach and play with drift nets, which can cause them to become entangled. (L.C. Personal observation) Habitat loss, pollution (marine litter) and culling by fishermen are additional threats to Grey seals on the Cornish coast. (Leeney et al.

2010) Conflicts between the fishermen and the seals due to decreasing fish stocks are posing a continuous threat to the seals around Cornwall and the rest of the UK. (Ibid) Although Grey seals are protected, the Conservation of Seals Act 1970 states that it is still legal for a seal to be shot under license if it is seen to be causing damage to fishing net or tackle or taking of fish from within the net, providing the seal is within the vicinity of net at time of shooting. (Kiely et al., 2000) The study of animal behaviour is known as Ethology. Since the 1980s, practical ethology has developed the ability to accommodate what is known as the normal behaviour of a species and be able to specify the abnormal behaviours. (Gonyou, 1994) Abnormal behavioural changes can be used to indicate reduced welfare or stress of the animal, which in turn indicates a factor of this abnormal behaviour which can then be looked into and potentially reduced. (Ibid) Behaviour and sightings of seals at haul out zones can be due to a variety of factors including time of year, (Sayer, Pers comms.) time of day, tidal cycles, weather and sea state. (Leeney et al. 2010) Human disturbance can also be a factor of behavioural changes of Grey seals at haul out sites. (CSG, 2011)

This study documents the behavioural comparison of Grey seals at two haul out sites in Cornwall.

METHODS AND MATERIALS Study areas Site one, Gwennap Head, lies on the most south-westerly coastal tip of England in Cornwall. Gwennap Head cliffs are exposed to the deep sea south-westerly swell (Fleming, 1995) of the Atlantic Ocean. Gwennap Head is one of the best seawatching sites in England (Walker & Wilson, 2007) with a tidal haul out zone used primarily by a local colony of Grey Seals.

SeaWatch SW Annual Report 2009 states that the numbers of Grey seal seen at the haul out at Gwennap Head remain stable, with a maximum of 20 Grey seals seen at one time on more than one occasion using the haul out site.

Human Activities occurring at Gwennap Head that could disturb the seals include crab and lobster potting, local fishing boats working in the area, commercial tour boats, and watersports including kayaking and recreational yachting and people walking along the cliff top. (L.C. Personal observation) Any disturbance including human activity plays a large part in the behavioural changes of marine mammals, including the Grey seals.

Venables, 2008 states that the haul out at Gwennap Head is a “regularly used low tide haul-out, often disturbed by boats passing between the haul out and the mainland. Once disturbed the Grey seals Halichoerus grypus often don't return that tide.�

The second site is located within the Fal estuary. The Fal is the third natural deepest harbour in the world, after Rio de Janeiro and Sydney. The Carrick Roads is 4 miles up the estuary from where Black Rock is located (PoT

Lauren Clegg & FHC, 2001) within the middle of the entrance of the Fal Estuary, on the South coast of Cornwall. Black Rock is a dark cone shaped beacon set on rocks, with two spheres located on top of its conical structure. (L.C. Personal Observation) Black Rock is a haul out area for a much smaller colony of Halichoerus grypus than at Gwennap head; this haul out is visible at low tides and submerged by water at high tide.

(Ibid) Human Activities occurring around Black Rock, Fal include watersports; scuba diving, powerboating, kayaking, sailing etc., recreational and commercial fishing, commercial tour boats (ORCA sea safaris) (L.C. Personal observation) Factors affecting Halichoerus grypus behaviour A variety of factors including time of year, time of day, tidal cycles, weather and sea state can cause a change in behaviour of Halichoerus grypus. (Sayer, Pers comms, 2011; Leeney et al. 2010) Human disturbance can also be a factor of behavioural changes of Grey seals at haul out sites. (CSG, 2011) Human disturbance can occur from land and also closer to the seals at sea, for example by boat and watersports activities.

Disturbance can be minimised by land based surveyors remaining quiet whilst surveying and if a seal notices them, for them to stay still and not pose any threat. (CSG, 2011) Boat based surveying can be controlled with a complete understanding of the marine mammal code of conduct. (WiSe, 2010) Data collection Scientific research today, including behavioural studies, tend to take place in laboratories in a controlled environment.

However, to understand behaviour at its most normal is in the natural environmental

surroundings, with most of behavioural studies taking place in the wild. (Bramwell Slater, 1999) Through the method of practical ethology, ethograms are used to record the variety of behaviours that the seals may express throughout survey times. An ethogram is defined as a list of species behaviours and actions that define them. (Smithsonian, 2010) Over a six week period, from 11/03/11 to 27/04/11, observations for Grey seal behaviour took place; twenty four observations overall.

Black Rock haul out was observed from Pendennis Point, Falmouth and the haul out at Gwennap head was surveyed from the cliff tops, beneath the coastguard station.

Twelve land based surveys took place at Gwennap Head with nine land based surveys at Pendennis Point; with three extra surveys being boat based within the Fal. At each survey, the tide times and height (neap and spring), weather and sea state were recorded; primarily to investigate whether the sea state had any effect on the behaviour of Halichoerus grypus. Tidal state was determined using the Mylor Yacht Harbour Tide Time Table 2011. The sea state was recorded using the Beaufort scale as guideline.

Observations were made during a two hour period starting one hour before and concluding one hour after the low tide time.

The time of day of each survey differ due to varying ebbing tidal times.

The number of seals and their behaviours were recorded using an ethogram, throughout the two hour period, to enhance the chance of seeing the seals behaviours change, such as movement from sea to land or vice versa, rather than surveying at set intervals.

Lauren Clegg Adler 10x42 binoculars were used for observations, with all photographs of various behaviours taken with a Canon 450D digital SLR camera with 70-300mm zoom lens. Any extra zoom or lighting adjustments required was altered with Microsoft Office Picture Manager.

DISCUSSION

RESULTS

The paired t-test was used to statistically analyse any comparison of behaviours between the two haul out zones, as the study of behaviour has been measured with the study occurring in a natural pair, due to study of same species: Halichoerus grypus.

Black Rock results were minimal, having only observed four Halichoerus grypus over the twelve, two hour surveys.

Black Rock haul out Grey seal visitors did not act distressed by human disturbance; main disturbance from boats, slowing down to look at the seals. All seals at Black Rock were surveyed as mostly lying with heads down, as if sleeping, or scanning the area around them, if disturbed, as if curious to what activity was happening around them; perhaps ensuring their safety.

One survey included sightings of a pod of up to twenty Bottlenose dolphins, swimming around Black Rock and into the bay; this did not distract the one seal surveyed that day to cause a change in behaviour.

Black Rock is situated in a much more sheltered position than the haul out at Gwennap Head.

Gwennap Head haul out provided a few more sightings, with much more behavioural activity within the water. From personal observation, higher sea states resulted in no sightings or sightings for a very short period of time.

The concluded t value of 0.73 has caused a rejection in the certainty of the two haul out sites being comparable of Halichoerus grypus behaviour.

Concluded factors affecting haul out behaviour include disturbance; both human and marine, sea state and tidal state.

This study is a vague baseline study for all flourishing future studies on the behaviour of Halichoerus grypus within the Fal estuary in comparison with other haul out zones in Cornwall.

Due to minimal results gained from Black Rock, a comparison between the behaviours of the two haul outs could not be made.

However, the tidal effects, such as neap and spring tides, had a slight effect on the appearance of the Halichoerus grypus at the Gwennap Head haul out.

The Halichoerus grypus did not show much movement at Black Rock, most lying as if sleeping or scanning when disturbed to see what was happening around them.

Whilst studying wild animals, there is no certainty that the animals will be where you want them at the time you wish to survey them. Primarily, the behaviour of wild animals, such as Halichoerus grypus, may be disturbed by the surveyor’s presence, which may become eased over time. To prevent any disturbance from the beginning, the land based surveys are better, due to distance and inability to get over to the haul out zones.

Also, land based surveying methods are low in cost, it is easy to return to the same/similar area of previous observation, however the observer is restricted to the vicinity of which you can only immediately see. (Evans & Hammond, 2004) Marine mammals in general are easier to locate on days of calm weather and seas. (WDCS, 2010) Boat based surveying methods can help with

Lauren Clegg repeat observations; however, the observer does not have any control as to where the boat is travelling, which may not be the same as previous observations. (Ibid) The three boat based surveys that took place in the Fal, allowed the observer to see if any Halichoerus grypus were hauled out on the side of Black Rock that is not visible from Pendennis Point, due to the conical “nautical marker” structure on the rocks.

Any boats causing any kind of disturbance were noted to be far enough away as to comply with the WiSe marine mammal code of conduct.

longer period of time, those seals that were already hauled out can be seen at the point of when they hauled out, which could also define peak haul out times before the lowest tide of the day. More behaviours may also be recorded if watched over a longer period of time.

project. This study did not obtain enough personal communication with Sue Sayer and has therefore suffered because of this.

The time of year of studying Halichoerus grypus certainly needs to be considered.

Personal communication with Sue Sayer of Cornwall Seal Group, whom has been studying Halichoerus grypus for over ten years, commented that the time of year that this survey has taken place, would not provide sufficient data due to little sightings.

However, continuous data collection for varying times during the year can decipher the time of year that Halichoerus grypus use the haul out within the Fal most.

The total time of this survey was 48hours, for future observations, this number need to be increased considerably to gain the results required to be able to reject a null hypothesis.

Further previous data could potentially be obtained from the Cornwall Seal Group for Halichoerus grypus haul out site at Gwennap head as this area has been studied previously and current data can be compared to previous data collections.

Personal input into the idea of purchasing a web cam to be placed on Black Rock will ease the surveying for those continuing the study of Halichoerus grypus in the Fal. I cannot stress enough how much personal communication with Sue Sayer of Cornwall Seal Group will help in every way with this

“Peak ebb and flood tide times were defined as three hours after and before high water, respectively.” (Leeney, 2010) This would come in handy for future surveys. The two hour surveys collected some behavioural data, however, if observations were taken over a

ACKNOWLEDGEMENTS The author would like to acknowledge the acquaintance and funding from Falmouth Marine School and Falmouth Harbour Commissioners.

Sue Sayer, Cornwall Seal group has been a huge aid with Halichoerus grypus expertise through personal communication and knowledge found on the Cornwall seal group website for input of different seal behaviours and building of personal ethograms for this survey; behaviours were continuously added to the ethograms over the surveying period.

Thank you to Luke Blakemore for all of his support and motivation throughout the survey.

REFERENCES Altmann, J. 1974. Observational study of behavior: sampling methods. Behaviour, Vol 49, pg 227-267.

Bonner, W.N. 1972. The Grey Seal and Common Seal in European Waters. Vol 10. pg461–507.

Bonner, W.N. 1989. The Natural History of Seals. Christopher Helm Publishers Ltd. ISBN: 0-7470-0203-7. pg 196.

Lauren Clegg Bowen, W.D. et al. 2002. Sustained exponential population growth of grey seals at Sable Island, Nova Scotia. ICES/CIEM International Publishing. Available through: http://icesjms.oxfordjournals.org/content/60/ 6/1265.full [04.12.10] Bramwell Slater, P.J. 1999. Essentials of Animal Behaviour. Cambridge University Press, 1999. ISBN: 978-0521629966. Available through: http://books.google.co.uk/books?id=sEOePcIF W0IC&lpg=PA1&ots=sfVnXz8okN&dq=animal %20behaviour%20ethogram&lr&pg=PA1#v=o nepage&q=animal%20behaviour%20ethogra m&f=false [01.12.10] CSG (Cornwall Seal Group) 2009. Grey Seals in Cornwall. [online] Available at: http://www.suesseals.eclipse.co.uk/Seal%20Fl ier%20landscape%20V10%202009.pdf [07.12.10] Evans, P.G.H & Hammond, P.S. 2004.

Monitoring Cetaceans in European Waters.

Mammal Rev, 2004. Vol 34, (1) pg 131-156 Fedak, M.A. et al. 1996. MAMVIS: A Marine Mammal Behaviour Visualization System. Volume 7, Issue 3. pg 141-147 Guillemin, J. 1980. Anthropological Realities: Readings in the science of culture. Transaction Publishers, 1980. ISBN: 978-0878557837.

Available through: http://books.google.co.uk/books?id=ddQwYc _2RGoC&lpg=PA444&ots=LD_F_9sEjg&lr&pg= PA446#v=onepage&q&f=false [04.12.10] Haug, T, M Hammill, D Olafsdottir 2007. The grey seals in the North Atlantic and the Baltic., The North Atlantic Marine Mammal Commission, Tromsø. NAMMCO Scientific Publications Vol. 6. Available through: http://www.marinemammalscience.org/index .php?option=com_content&view=article&id= 476&Itemid=309 [05.12.10] Higham, J.E.S. & Luck, M. 2008. Marine Wildlife & Tourism Management: Insights from the Natural and Social Sciences. CABI

Publishing, 2007. Available through: http://books.google.co.uk/books?id=TsRZW0 dU6MC&lpg=PA182&ots=O1JFouXMaG&dq=grey %20seal%20code%20of%20conduct&lr&pg=P A182#v=onepage&q&f=false [01.12.10] IUCN, 2010. Red List of Threatened Species. [online] Available at: http://www.iucnredlist.org/apps/redlist/detai ls/9660/0 [05.12.10] IUCN: The World Conservation Union, 1995.

Seals. Cambridge: IUCN Publications. ISBN 28317-0049-3 Kiely, O. et al. (2000). Grey Seals: Status and Monitoring in the Irish and Celtic Seas.

Maritime Ireland / Wales. Report No. 3. ISSN: 1393-9025. Pg 77 Leeney, R.H. et al. 2010. Abundance, distribution and haul-out behaviour of grey seals (Halichoerus grypus) in Cornwall and the Isles of Scilly, UK. Vol 90(5). Pg 1033-1040 Lewis, K.M. 2006. Habitat Use, Haul-Out Behaviour & Site Fidelity of Grey Seals (Halichoerus grypus) along the Ceredigion Marine Heritage Coast, Wales. Pg 1-30 Lockley, R. M. 1966. A ‘Survival’ Book: Grey Seal, Common Seal: An account of the life histories of British seals. White Lion Publishers Ltd. pg 175.

McConnell, B.J. et al. 1999. Movements and foraging areas of grey seals in the North Sea. Vol 36. Issue 4. Pg 573-590. Available through: http://onlinelibrary.wiley.com/doi/10.1046/j.

1365-2664.1999.00429.x/full [05.12.10] Moore, P.G. (2003). Seals and fisheries in the Clyde Sea area: traditional knowledge informs science. Fisheries Research, Vol 63. Pg 51-61 Natural England. 2009. Formal consultation starts on proposed European marine sites: EC Habitats Directive 1992. [online] Available at:

Lauren Clegg http://www.naturalengland.org.uk/about_us/ news/2009/271109.aspx [04.12.10] Port of Truro Authorities, 2001. The Fal Estuary. [online] Available at: http://www.portoftruro.co.uk/pdf/leaflets/fal est.pdf 2001 [05.12.10] Prime, J.H. 1985. The Current Status of the Grey Seal Halichoerus grypus in Cornwall, England. Vol 33. pg 81-87 Riedman, M. 1990. The Pinnipeds: Seals, Sea Lions and Walruses. University of California Press, 1990. ISBN: 978-0520064973. Available through: http://books.google.co.uk/books?id=McNEUg U8Q58C&lpg=PR9&ots=hn4tDRuYhR&dq=pin nipeds&lr&pg=PP2#v=onepage&q&f=false [04.12.10] SCOS, 2007. Scientific Advice on Matters Related to the Management of Seal Populations. pg 1-93. Available through: http://www.smru.standrews.ac.uk/documents/SCOS_2007_FINAL _ADVICE_1.pdf [04.12.10] Smithsonian Institution, 2010. Vocabulary list. [online] Available at: http://nationalzoo.si.edu/Education/Classroo mScience/vocabularylist.cfm [06.12.10] SMRU: Sea Mammal Research Unit. 2010. Seal Diet. [online] Available at: http://www.smru.standrews.ac.uk/documents/SealDiet.pdf [05.12.10]

Steven G.A. 1932. A short investigation into the habits, abundance and species of seals on the North Cornwall Coast. Report to the Ministry of Agriculture and Fisheries, 30 December 1932. Available through: http://sabella.mba.ac.uk/823/01/A_short_inv estigation_into_the_habits,_abundance,_and _species_of_seals_on_the_North_Cornwall_c oast.pdf [05.12.10] Summers, C.F. 1974. The Grey Seal (Halichoerus grypus) in Cornwall and the Isles of Scilly. Vol 6, No 4. pg 285-291 Thompson, P. & Rothery, D.P. 1986. Age and sex differences in the timing of moult in the common seal, Phoca vitdina.[05.12.10] Walker, D. and Wilson, A. 2007. Whales and Dolphins of Great Britain: Where to go and What to see. Loughborough: Cetacea Publishing.

Wynn, R.B. et al. 2009 SeaWatch SW Annual Report 2009. pg 2-5

Lauren Clegg APPENDICES STATISTICS Paired t-test Behaviours

Black Rock Gwennap Head 0 2 2 0

BT IO HL LY GR SK BN DV PR SC

-2 2

1 8 0

3 3 1

-2 5 -1

s=

0 2 0 0 5

3 0 6 7 2

-3 2 -6 -7 3

∑x 2 mean =

√

s= √

∑x 2 n

mean2

145 -0.9 145 10

s=

- 0.81

3.7

t

test = - 0.9 √ (10-1) = 0.729 3.7

Degrees of freedom = 10 - 1 = 9 Critical value = 1.833 t value is lower than the critical value so null hypothesis can not be rejected

©Brilliant stats, Curriculum Press 2003

H0: there will be no difference in the behaviour between two haul out sites- CANNOT BE REJECTED H1: there will be a difference in the behaviour between two haul out sites - REJECT ETHOGRAM USED DURING SURVEY BT

Bottling

LG SP IO

Logging Splashing Interaction with other seals

FD

Feeding

HL

Hauling from sea to land

EW

Entering water from land

LY

Lying

GR FN TK SK

Grooming Fanning Tracking Snorkelling

BN

Banana-ing

Sleeping upright in the sea. Head will rise and sink at the surface.

Sleeping in the sea horizontally.

Sudden diving action if disturbed.

Grooming, playing etc. with other seals.

Can be seen eating fish, crabs etc. usually at the surface of the water.

A seal will haul from the water onto haul out zone.

A seal will enter the sea from the haul out zone.

Sleeping motionless on land on their backs or sides.

Scratching themselves with their paws.

Stretching back flippers into a fan.

Surfacing behind a boat following it.

Blowing bubbles whilst swimming at the surface.

Seal tail and head held high, in a U or banana shape.

Lauren Clegg DV PR

Diving Periscoping

SC

Scanning

Diving underwater suddenly.

Head held high whilst in water, looking around.

Looking around whilst hauled out on land

MAPS/GRAPHS

Total Number of Halichoerus grypus Observed 10 8 6 4

Number of Halichoerus grypus observed

2 0 Black Rock

Gwennap Head Haul Out Sites

Number of times actions tae place

9

Behaviours of Halichoerus grypus observed at two haul out zones

8 7 6

Black Rock

5

Gwennap Head

4 3 2 1 0 BT LG SP IO FD HL EW LY GR FN TK SK BN DV PR SC Behaviour

Lauren Clegg GWENNAP HEAD Gwennap Head haul out site

View point, Cliff tops of Gwennap Head

Behaviours observed at Gwennap Head SC

LY

SK

3%

BT

5%

DV

PR

HL

GR

4%

9% 3%

46%

16%

14%

26/04/2011

24/04/2011

22/04/2011

20/04/2011

18/04/2011

16/04/2011

14/04/2011

12/04/2011

10/04/2011

08/04/2011

06/04/2011

04/04/2011

02/04/2011

31/03/2011

29/03/2011

27/03/2011

25/03/2011

23/03/2011

21/03/2011

19/03/2011

17/03/2011

3

15/03/2011

13/03/2011

11/03/2011

09/03/2011

Lauren Clegg

3.5

Gwennap Head: Tidal height variation vs. Seal observations

2.5

2

1.5 tidal height /m

1 Number of Grey seals

0.5

0

BLACK ROCK, FAL ESTUARY

View point, Pendennis Point, Falmouth

Black Rock, Haul out site

18/04/2011

16/04/2011

14/04/2011

12/04/2011

HL

10/04/2011

IO

08/04/2011

SC

06/04/2011

0%

04/04/2011

LY

02/04/2011

31/03/2011

29/03/2011

27/03/2011

25/03/2011

23/03/2011

21/03/2011

2

19/03/2011

2.5

17/03/2011

15/03/2011

13/03/2011

11/03/2011

Lauren Clegg

Behaviours observed at Black Rock BN

2%

16%

4%

78%

Black Rock: Tidal height variation vs. seal observations

1.5

1 Tidal height

Number of seals

0.5

0

Lauren Clegg MARINE MAMMAL CODE OF CONDUCT Marine mammal watching has become a huge tourism industry; in turn needing to create a code of conduct, for the correct manner of behaviour whilst watching these creatures and with the tourism increasing as does the knowledge and conservation of these wonderful marine mammals. (Garrod & Fennel, 2004) All wild marine mammals are vulnerable to disturbance of any kind if not approached correctly. There must be complete understanding of the code for it to work. (WiSe, 2010) Code of Conduct as put forward by the Cornwall Wildlife Trust:        

Keep your distance Never drive a boat head on into a group of animals as to separate them Please spend no longer than 15 minutes near these animals Avoid groups with mother and young Never be a cause of marine litter or marine contaminants – take your rubbish home Never swim with a marine mammal, for both your safety and theirs Maintain a steady direction, preventing any wake Never attempt to feed a wild marine mammal