The mass death of Razorbills in the Skagerrak, autumn 2007

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Marlene Thompson
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1 4 th Seminar Clarion Hotel & Congress, Trondheim April 2013 The mass death of Razorbills in the Skagerrak, autumn 2007 What did we learn? Tycho Anker-Nilssen NINA, Trondheim

The Razorbill Alca torda The least abundant pelagic auk in the Atlantic World population estimated at 610,000-630,000 pairs (Merne &

2006), all ssp. A. t. torda Skagerrak & Kattegat most important wintering areas (e.g. Skov et al.

2 The Razorbill Alca torda The least abundant pelagic auk in the Atlantic World population estimated at 610, ,000 pairs (Merne & Mitchell 2004) 94% breed in the NE Atlantic, including All 530,000 pairs of ssp. A. t. islandica (Britain, Faroes, Iceland) 25,000 pairs in Norway (Barrett et al. 2006), all ssp. A. t. torda Skagerrak & Kattegat most important wintering areas (e.g. Skov et al. 1995) Conservation status IUCN: Least concern (LC) Norway: Vulnerable (VU) Trends EN, but UK pop. stable Svalbard: Endangered (EN) Only pairs (Strøm 2006)

(2011) Mass mortality of adult Razorbills

3 This study published in Seabird vol. 24 Heubeck, M., Aarvak, T., Isaksen, K., Johnsen, A., Petersen, I.K. & Anker-Nilssen, T. (2011) Mass mortality of adult Razorbills Alca torda in the Skagerrak and North Sea area, autumn Seabird 24:

Initial weather during the 2007 wreck 14 th Sept: A deep depression entered the North Sea SW NW gales (up to 37 knots) SW gales in N Skagerrak (mean 35-36 knots, Svenner &

4 Initial weather during the 2007 wreck 14 th Sept: A deep depression entered the North Sea SW NW gales (up to 37 knots) SW gales in N Skagerrak (mean knots, Svenner & Færder) Next 10 days: Predominantly SW winds in the Skagerrak Mean 17 knots (Svenner) First boost of auks Oslofjorden: 14 th Sept N W Sweden: 17 th Sept SE Skagen, DK: 17 th Sept SE

Razorbills passing Møringa 2006-07 1400 Number of Razorbills observed 1200 1000 800 600 400 200 0 200 20-27 th Sept C. 15,000 auks, mostly Razorbills C.

5 Razorbills passing Møringa Number of Razorbills observed th Sept C. 15,000 auks, mostly Razorbills C. 7,000 entered Inner Oslofjord Inland reports > 100 Razorbills 200 km inland Møringa 1 st 2007 SEAPOP Seminar th Oct Date

6 Holmen Fjordhotell 17 th Oct 2007 Pocket camera snapshot during coffee break

7 Observations of auks in SE Norway Data from

8 Observations of auks in W Sweden Data from

9 Large nos. of auks were beached Oslo Opera House Kjell Isaksen

10 Large nos. of auks beached Kjell Isaksen

11 Thousands of dead razorbills At least several thousand, perhaps over 10,000 Razorbills died in the wreck (Isaksen & Bredesen 2007) Kjell Isaksen

12 North Sea-wide incident Beached Razorbills in regular BBS schemes German Friesian Islands ( ) Noord Holland and Wadden Sea Islands ( )

Shetland (1979-2010) North Sea-wide incident Beached

13 Shetland ( ) North Sea-wide incident Beached Razorbills in regular BBS schemes Orkney ( , )

Veterinarian examinations (n=9) Kjell Handeland Norwegian Veterinary Institute No signs of avian flue All severely emaciated Moderate parasite

14 Veterinarian examinations (n=9) Kjell Handeland Norwegian Veterinary Institute No signs of avian flue All severely emaciated Moderate parasite loads Moderately infected by stomach nematodes 1 Razorbill heavily infected by intestinal trematodes Similar results for common guillemots (n=5)

15 Not all birds suffered Four birds shot under license on 5 Oct. off eastern Jutland, DK Full of fish Apparently in good condition Pectoral muscles 2X as heavy as of those beached at Skagen

16 Post mortem studies at NINA (n=376) Starvation! All adults in extremely poor condition Average body mass 30% (females) and 34% (males) lower than those killed in Stylis oiling incident winter 80/81 Tomas Aarvak at work

Age and sex distribution Mainly adults were hit 4% juveniles (bursa, 0 bill grooves) 9% immatures (1-2 grooves) 87% adults (no bursa, 3-4 grooves) Mainly females were hit Juveniles: 60% female (n=15,

17 Age and sex distribution Mainly adults were hit 4% juveniles (bursa, 0 bill grooves) 9% immatures (1-2 grooves) 87% adults (no bursa, 3-4 grooves) Mainly females were hit Juveniles: 60% female (n=15, ns) Immatures: 58% female (n=33, ns) Adults: 71% female (n=327, p<0.001) Females arrived first? The male accompanies the flightless young at sea after leaving the colony No skewed sex distribution in winter (e.g. 49% females, Anker-Nilssen et al. 1988) Molecular sex was determined for 77 birds based on primers P2 and P8

18 18% of adults had 2 white bill grooves Lavers et al. (2005) found 34% 2W-birds in a Newfoundland sample from Aug-Nov (n=29) Edge of white groove apparently peeling off? An autumn phenomenon? Moulting outer white groove? i.e. transitional 2W1+ 1W2+?

19 Origin based on (clinal) size variation Barrett, R.T., Anker-Nilssen, T. & Krasnov, Y.V Can Norwegian and Russian Razorbills Alca torda be identified by their measurements? Marine Ornithology 25:

(1988) Age, sex and origins of auks (Alcidae) killed in the Skagerrak oiling incident of

20 Origin of birds; former experience Stylis oil spill incident, Skagerrak Dec-Jan 1980/81 Anker-Nilssen, T., Jones, P.H. & Røstad, O.W. (1988) Age, sex and origins of auks (Alcidae) killed in the Skagerrak oiling incident of January Seabird 11: Sub-species A. t. torda (Baltic, Norway, Russia) Sub-species A. t. islandica (British Isles, Faroes, Iceland)

21 2007: Adults still in active moult Hard, transparent shaft - End sealed Longest primary Soft, opaque shaft End open

) in Dec-Jan (1980/81) Mean wing length 8.

22 Origin of birds killed in 2007 Adults (Sept-Oct) were still in active wing moult Mean wing length 6.9 mm shorter than in juveniles Adults (islandica ssp.) in Dec-Jan (1980/81) Mean wing length 8.8 mm longer than in juveniles (Anker-Nilssen et al. 1988) Remaining wing growth estimated to be approx = 15.7 mm mm

23 Origin of birds killed in 2007 Sub-species A. t. islandica (British Isles, Faroes, Iceland)

24 Only Scottish birds involved? All ringed birds (26) originated from Scottish colonies (10) No juveniles Mean age 11y+ (range 1 19y+)

25 All ring recoveries in Oslofjorden Bakken & Anker-Nilssen (2012) Origin of seabirds on the Norwegian coast outside the breeding period. Report to the Norwegian Oil an Gas Association (In Norwegian)

26 All ring recoveries in W Skagerrak Bakken & Anker-Nilssen (2012) Origin of seabirds on the Norwegian coast outside the breeding period. Report to the Norwegian Oil an Gas Association (In Norwegian)

Population trend in Scottish colonies Significant

2006 Effect expected to show in 2008 when survival

Monitoring programme Was the incident part of a

27 Population trend in Scottish colonies Significant decrease with increasing inter-colony variation after 2006 Effect expected to show in 2008 when survival rate dropped on Isle of May Courtesy of JNCC Seabird Monitoring programme Was the incident part of a longer-term problem initiating before the 2007 breeding season?

Razorbill genetics; samples stored Moum & Árnason (2001) Molecular Ecology 10: 2463-2478 Muscle tissue

28 Razorbill genetics; samples stored Moum & Árnason (2001) Molecular Ecology 10: Muscle tissue sampled from 371 individuals by Arild Johnsen Stored at the DNA archive, Natural History Museum, Univ. Oslo

29 Thanks to Martin Heubeck and the other co-authors to the Directorate for Nature Management for funding the autopsies at NINA to YOU for listening!

30 Time for lunch!

Mass mortality of adult Razorbills Alca torda in the Skagerrak and North Sea area, autumn 2007

Mass mortality of adult Razorbills Alca torda in the Skagerrak and North Sea area, autumn 2007 Heubeck, M. 1*, Aarvak, T. 2,3, Isaksen, K. 4, Johnsen, A. 5, Petersen, I. K. 6 & Anker-Nilssen, T. 2 *Correspondence