Godrevy Seal Group. Report of Seal activity at Godrevy, Cornwall. Volume 3 : May /06/2005 1

Transcription

1 Godrevy Seal Group Report of Seal activity at Godrevy, Cornwall Volume 3 : May /06/2005 1

2 Report of Seal activity at Godrevy, Cornwall. 12/08/04 to 30/05/05 Written by Sue Sayer on behalf of the Godrevy Seal Group Introduction The Godrevy Seal group held its first meeting on 20/02/04 attended by 8 members. In total 8 meetings have been held, one every 2 months and they have been attended by 22 different people, who have come from as far away as France and Australia! The group is becoming a focal point of contact for people both locally and further a field. Links have been established with Oceanopolis in Brittany and Nic Jouault doing seal ID work in Jersey. Identification work began using photo ID sheets, then by sharing seal ID photo catalogues and finally at ID workshops held during meetings. This work has been supported by monthly ID webpages at Record sheets have been constantly updated in the light of experience. At each meeting record sheets have been left for collation and analysis. Volume 1 was the Godrevy Seal Group s first report was written on 11/04/04. It covered 2 months of observations and included the group s aims. (Figures in red) Volume 2 was a summary of all our observations between 04/04/04 and 12/08/04. It covered 4 months and included comparative figures from volume 1, to begin the process of tracking and identifying trends in numbers, identification and behaviour. (Figures in blue) Volume 3 covers observation work carried out between 12/08/04 and 30/05/05, a period of about 9 months. Future Godrevy Seal Group reports will be compiled annually. Copies of previous reports can be downloaded from see Downloads section. Location During this period of observation, the seals hauled out at 2 locations. The first is Mutton Cove (SW on the OS Landranger Map number 203.) Seals were seen here most of the time. This is a north facing cove on Godrevy Headland, sheltered by a rocky gullied wave cut platform accessible at low water. The second is the exposed rocky ledge in front of Godrevy Island (SW to on the OS Explorer Map Number 102.) Seals were seen here at the very start and end of the observation period only. Mutton Cove Rock ledges land side of Island 02/06/2005 2

3 Method 5 (3; 6) sets of observation records were submitted between 12/08/04 and 30/05/05 inclusive by Terry Hocking, Kate Hockley, Lesley and Dave Jarvis, Dan Jarvis and Sue Sayer. Our record sheet looks like this. Observers complete as much as they feel able. Date Total seals hauled on MC Number hauled on islands off MC No. of other seals in water Number of seals hauled on Light house Island Total Number of M:F:J:P:W:? Males Females Juveniles WCPups Weaners Other Incl number of ring necked % Ring Neck Number of seals ID'd % ID'd New seals ID'd List of ID codes State of the Tide - hours past low or high. Going in or out Sea force Wind force Wind direction Disturbance? Yes/No and Type. Specify people descending path Other info and comments Where possible, observers made contemporaneous records and took video or still digital images of their observations, enabling shared and retrospective identification of individual seals. This has been particularly successful and allows members with more identification experience to support others with their identification work, increasing the accuracy of our records. A range of binoculars, telescopes, digital still cameras and digital camcorders were used for identification work. A total of 285 (70; 80) different observations were made on 213 (75%) (52, 40%; 43, 54%) different days out of a possible 291 (130; 56) days. Results : Seal numbers Average seal haul out numbers have been higher in October, November, February, March, April and May 2005 (April, May and July 2004; Feb and March 2004) than in the same months in the previous 4 years. This graph shows that for 6 out of the last 12 months, average seal numbers at this location have been at their highest ever. For February and March, the average numbers have been more than double the previous highest recorded. As seal population numbers in the South West are not increasing (Source SMRU 2004) this suggests that seals are moving into this location in preference to others in the region. Average Seal haul out numbers at Godrevy Average Seals observed Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Dates 02/06/2005 3

4 Number of seals observed at Godrevy by Godrevy Seal Group Number of seals /08/ /08/ /09/ /09/ /10/ /10/ /11/ /11/ /12/ /12/ /12/ /01/2005 Dates 27/01/ /02/ /02/ /03/ /03/ /04/ /04/ /05/ /05/2005 Seals were seen on 90% of visits (100%; 100%.) Seals hauled out on 237 occasions (55, 73.) which represents 83% of visits (78%, 91%.) There were 2 peaks in seal numbers in October and March. The Spring haul out peak was one month earlier than seen in previous years. Seals hauled on Island ledges up to 31/08/04. Their preferred haul out site moved to Mutton Cove about 6 weeks earlier than in previous years on 28/08/04. Frequency of seal numbers observed between 12/08/04 and 30/05/ Frequency of observations to 4 5 to 9 10 to to to to to to to to to to to to to to to to to to to to to 114 Number of seals 02/06/2005 4

5 Observations of over 20 seals occurred 157 times (35; 48) during 55% of visits (50%; 60%.) The most frequently observed number of seals was 0 to 4 seals (5 to 9; 10 to 14) seen 45 times (11; 13.) The average number of seals observed at Godrevy was 31 (33; 31) which is a very consistent figure. Numbers observed ranged from 0 (1; 2) to a peak of 112 (95; 81) on 19/03/05, when all 112 seals were on the beach. This is the largest haul out reported on Mutton Cove since 25/06/00.) Results : Vagrant Seals No (0; 2) vagrant seals were observed during this period. Results : Seal identification Much progress has been made with the identification of individual seals. A total of 160 (100; 66) different individual seals were identified and their images recorded digitally. Of the 160 (100; 66) different seals identified 49 (31%) (37, 37%; 22, 33%) were females and 102 (64%) (63, 63%; 44, 67%) were males and 9 (5%) were pups. These figures have remained reasonably constant across all 3 reports and suggest males form about 2/3 and females 1/3 of the seal population at this location. The number of seals identified during a single visit ranged from 0 to 24 (0 to 25; 0 to 16) different individuals. Age/sex breakdown of identified seals Females Males Pups 14 (4; 2) different tagged seals were seen on 30 occasions, representing a significant increase. 7 of these seals have been released from the National Seal Sanctuary - Puffa (yellow tag 079); Snout (yellow tag 037); Sweet Pea (white tag 012); Neil (white tag 007); Lewis (yellow tag 047); Goose (blue tag 025) and Winter (pink tag 040.) The young male seal with a red tag 52693, released from Oceanopolis in Brittany was seen again along with another 6 seals with unidentifiable yellow, orange and brown tags. In future, the National Seal Sanctuary will use double sided tags to make identification easier. 4 (2; 0) yellow hatted seals were seen. Pauline (08) was seen again, as well as Blyth (10), Brant (42) and Lune (43.) All the seals, apart from Pauline had been released at Gwithian. 02/06/2005 5

6 One seal had a head scar as if it had previously worn a hat or transmitter. This adds to the current debate about their attachment. 72 (30; 12) seals were identified 5 or more times. Of these seals, 55 (2; 5) are male, 13 (6; 5) are female and 4 are pups. 6 (5; 4) seals seen more than 5 times are net ringed. Some seals spend more time than others at Godrevy. Seal visits could be classified as Semi resident (17 seals seen more than 20 times); Regulars (54 seals seen between 5 and 19 times) and Migrants (88 seals seen less than 5 times.) The most frequently identified seal was only seen on 20% of visits, so no seals can be classed as Resident. Of the identified seals seen more than 5 times, 55 are male, 13 are female seals and 4 are pups. This suggests that the males stay around longer and adds weight to the idea that this is a male dominated location. Number of times an identified seal was seen Number of seals to 4 5 to 9 10 to to to to to to to to to to 59 Number of observations of an individual seal Frequency of percentage of seals identified Frequency to 4 5 to 9 10 to 15 to 20 to 25 to 30 to 35 to 40 to 45 to 50 to 55 to 60 to 65 to 70 to 75 to 80 to 85 to 90 to 95 to 100 to /06/2005 Percentage of seals identified 6

7 The most frequent percentage of seals identified per visit remains at 0 to 4% (0 to 4%; 0 to 4%) of the total number of seals present, although on three occasions 100% (71%; 47%) of the seals were identified. The average percentage of seals identified during observations went up to 18% (15%.) Seal identification work demands skills that take a long time to develop, but these figures show significant progress is being made and all observers can now identify at least a few individual seals accurately. This slow process is supported by retrospective identification work from digital images by the most experienced member. As all observers get more confident and capable, these figures will continue to rise. Results : Purpose of beach for seals The small and infrequent number of pups born on this beach since 2000 has meant that the haul outs have been male dominated and the main function a non breeding one. This changed in December 2004 as 3 pups were born on the haul out beach between 29/11/04 and 01/01/05. As this beach had not previously been a breeding beach, dominant male behaviour had not been seen. On the day the second pup was born (04/12/04) a short, but loud, splashy fight took place in the water between two males. The victor (DP176) became the Beachmaster. DP176 seemed to be a recently mature male, perhaps dominating a location for the first time, and he kept all but a few females and immature seals off the beach between 04/12/04 and 21/12/04. Thereafter he mated with the second female (S164), after which she continued to feed her pup. The Beachmaster remained with this second mother on one side of the beach, whilst the haul outs increased at the other end of the beach. Pup growth and development could be observed throughout the period up to weaning, after which the pups disappeared. Neither of the first two mothers had been seen at this location before, but one of them (S163) has since been seen on the haul out beach. The third mother (S31) was identified as a known seal, who has been observed on a few visits each year since 17/11/01. This may have been her first pup. Results : Seal and human interaction Seal information for the public Godrevy Seal Group members have hosted 3 Seal Walks and Talks to raise public awareness about Grey Seals in Cornwall with the aim of increasing levels of understanding and support for the Seals. The National Trust have held 2 and Kehelland School : Official Guardians of Godrevy requested the third. 3 more events are planned : Cornwall Wildlife Trust s Marine Week - 11/08/05; National Trust 27/11/05 and March See website for details ( Godrevy Seal Group members give out Seal and Marine Mammal Emergency Rescue leaflets at Godrevy on a regular basis and a box of resources for the public to use is planned. Net entanglement The average percentage of net entangled seals remained at a very consistent 4% (4%; 4%.) A total of 13 (15; 11) out of 160, 5% (100, 15%; 66, 17%) seals identified had some form of net entanglement. The forms of entanglement included neck rings 11 (13; 8) seals, abdominal rings (belts) 2 (2; 3) seals. The real percentage for net entangled seals 02/06/2005 7

8 is likely to fall somewhere between these 3 sets of figures, which is in line with the 8.3% calculation of net entangled seals made between 25/06/00 and 12/02/05. Another 2 rescues (1; 2) of net entangled seals were attempted, only one of which was successfully carried out on 22/05/05, as a collaboration between our group, the British Divers Marine Life Rescue and the National Seal Sanctuary. Here a young female had monofilament line cut from her neck before she was released back into the wild. On 30/01/05, 2 net entangled seals one with trawl net and the other with monofilament were too close to the sea to make a rescue attempt worthwhile. Sadly neither seal was seen again. Disturbance The National Trust, erected a sign on 18/02/04 requesting visitors not to descend the path to the beach, appears to have been a great success. People were seen going down the path on only 2 occasions representing 1% of visits. (7, 10%; 6, 7.5%.) However, the general level of disturbance continues to be of concern. Seals hauled on the beach were observed to be disturbed on 29, 10% of occasions (7, 10%; 17, 24%.) Disturbance was caused by onlookers moving or making a noise on the cliff top 12 times (4). Perhaps we could encourage people to be aware of the need to be reasonably quiet on the National Trust signs on approaches to the cliff top. Low flying aircraft and helicopters disturbed the seals 3 times (3; 5.) A new cause of disturbance comes from the sea. Jetskis disturbed large numbers of seals on 4 occasions, boats on 2 and ocean kayaks once (on this latter occasion, the kayakers were seen feeding the seals around them with fish. Experience from Newquay Harbour has shown the problems this kind of behaviour can lead to.) The other 7 incidents of disturbance were caused by unknown factors. It is anticipated that this kind of disturbance is likely to get more frequent, especially with the possible development of Hayle Harbour. An action plan needs to be drawn up before the seals are disturbed away from this location for good. Dead Seals Dead seals have been rare at Godrevy, about 3 having been seen between June 2000 and August 2004 and all were white coat pups. During the 9 months of observation for this report, 5 dead seals were reported to Seal Group members, none of which were white coat pups. One young seal had lost its head, leaving a clean, smooth neck wound. We are keen for members of the public to report all dead seals, so this can be monitored closely. Seal Release 4 (1) seal releases of 13 (2) seals have taken place from a site at Gwithian, close to the haul out locations. These took place in January, March and 2 in May of the 13 released seals have been seen amongst the haul outs or with other seals in the sea. 02/06/2005 8

9 Comparative Analysis across all reports Volumes 1 to 3. Overall 8 different observation teams submitted records for the 3 volumes of reports and 5 submitted records for this report. Volume 3 has the highest percentage of days covered, despite being over a much longer period. Credit for this goes to Terry Hocking who has painstakingly photographed and recorded his very frequent visits to study the seals. Seals were seen on 90% to 100% of visits and were hauled out on between 78% and 91% of the visits in all 3 volumes. 20 or more seals were seen on 50% to 60% of all visits. This indicates the considerable consistency of seal visits to this location. This is one of the few places where it can be said that seals can be seen all year round. Godrevy also represents perhaps the most accessible seal haul out site in the UK. For most of the year their proximity to the car park means they can almost be described as roadside. This brings its own benefits and problems, making the need for strategic planning more important than in most places. The seals haul out at 2 sites. Between October (August in 2004) and May they haul out on Mutton Cove. Between May and October (August in 2004) the seals preferred haul out site moves to the ledges on the south east or landward of the island. The average number of seals observed has remained very constant between 31 and 33 seals. This is surprising as the raw data suggests that seal numbers are increasing at this location, though not across the South West in general (Source SMRU 2004.) This consistent average number is linked to the fact that no seals were seen on 10% of occasions in Volume 3, whilst peak haul out numbers increased to over 100 on 4 occasions for the first time ever. It is also linked to the greater range in seal numbers and the presence of a Beachmaster in December The range in the number of seals seen on one visit has increased. It is now 0 to 112. Vagrant seals were only reported in volume 1, as sightings of vagrant seals are not a common occurrence on this coast. The number of seals that were identified by observers has increased steadily from 66 in the first Volume to 160 in this Volume. This is very encouraging and reflects the increasing skills of the observers and the relative success of our observation methods. It is very satisfying to hear members of the group identify seals independently! The percentage of females reported ranges between 31% and 37% of all seals seen. The percentage of males reported ranges between 63% and 67% of all seals seen, confirming that this is a male dominated location. The percentage of pups reported in Volume 3 was 3% of all seals seen. This figure had not been included previously, reflecting the fact that this beach became a breeding beach for the first time since The presence of the Beachmaster had some effect on average haul out figures. The range in the number of seals identified in one visit is 0 to 25 seals and shows the developing identification skills of observers. Considerably more tagged and hatted seals were reported in Volume 3. This could be because interest and awareness levels of observers have been raised. The National Seal Sanctuary have used Gwithian 4 times for releases, increasing the density of hatted and tagged seals in the locality. A lot more seals were identified more than 5 times in volume 3 (72) than in Volume 2 (30) and Volume 1 (12.) This is a significant increase possibly due to the longer observation period, partly to seals staying around longer and partly because more teams were able to identify certain seals. 02/06/2005 9

10 This appears to be a male dominated population (2/3 males and identified males are seen more times than identified females.) In December 2004, this became a breeding location with a dominant male for the first time since June The percentage of net entangled seals seen on any one occasion ranges between 5% and 17%, although the overall average percentage of net entangled seals seen throughout the period has been very stable at 4%. An accurate figure probably lies between all these figures. The most frequent percentage category of seals identified remained at 0 to 4% in both Volumes. Identification work is still in its infancy and remains very challenging. The highest percentage of seals identified on a single visit increased a lot in Volume 3 rising to 100% for the first time - this was achieved on 3 occasions. This compares to 71% in Volume 2 and 47% in Volume 1. This could reflect the increasing identification skills of observation teams and the use of digital imagery for retrospective identification. The methods of net entanglement remained roughly the same. In total, 4 successful rescues took place during the study period, plus one that had to be abandoned. There was a significant drop in the percentage of occasions when people were seen going down the path (1%), a drop from 10% is excellent. Overall disturbance has dropped from 24% of occasions to 10%. This too is great news. Disturbance of hauled seals by aircraft has decreased from the start of the observation period from 5 times to remain stable at 3 occasions. Disturbance, however, remains a significant concern. The number of times disturbance took place by onlookers and their dogs from the cliff top has increased from 4 to 12 times and the number of times the seals were disturbed by sea craft increased from 0 to 7. A strategic management plan is needed to prevent further increases. Evaluation Early volumes of reports needed to be more frequent to encourage observers to invest their energy in the time consuming and slow process of seal identification work. Each volume covers a significantly different amount of time, which is far from ideal. Observations take place when volunteer members have time to go out to observe the seals. Considerable time and effort is needed to make records whilst on the cliff top. Identification work requires expensive equipment that volunteers pay for themselves. Identification skills take years to develop and require a considerable degree of patience and perseverance. Photos have to be transferred to computer and records have to be written up and submitted for collation. It takes about 30 hours to collate and compile a report, so it is miraculous that the Godrevy Seal Group members have achieved 3 reports in 15 months! It is anticipated that future reports will be annual. Circulation of this report Parties that have an interest in the seals at Godrevy will be provided with a copy of this report. Feedback is welcomed. Anyone wanting to join the Godrevy Seal group is encouraged to look at the Godrevy Seal Group website at Copies of this report can be downloaded from the Downloads section of the website. You can contact the Godrevy Seal Group by ing ssayer@suesseals.eclipse.co.uk. Seal observers contributing records : Huge thanks to you all! Tim Bain, Caroline Curtis, Gary Hawkins, Terry Hocking, Kate Hockley, Dan Jarvis, Dave Jarvis, Lesley Jarvis, Yvie Oxley, Sue Sayer, Sue Waterhouse, Trevor Waterhouse 02/06/