General Overview

South Jason is situated in the NW of the Falkland Islands archipelago. The island is approximately 7 km in length and 1km wide at it's widest point. There is a steep central ridge running the length of the island which reaches a maximum height of 315m. At the eastern and western ends the ridge flattens to form plateaux. Much of the terrain is difficult to cross.

The South Coast Looking East Showing Burnt Tussac

The inspection and ground survey of South Jason Island was carried out on Monday 12th February. Five fieldworkers were involved; Becky Ingham - Conservation Officer, Nic Huin - Albatross scientist, Aidan Kerr- Senior Agronomist at the Department of Agriculture and Falklands Conservation Trustee, Alan Henry - local ornithologist and Falklands Conservation Trustee, accompanied by Ben Ingham, Military Press Officer. The team were taken to South Jason Island, in a Sea King helicopter courtesy of 78 Squadron, to assess damage following the recent fire. The trip was carried out later than originally intended, following delays due to bad weather.

The group departed Stanley at 1030 hours and arrived South Jason at 1225. On reaching the island, the helicopter flew along the coast for a general overview. Fires were still burning on the north-eastern coast and those that have reached the far point at the north-east end appear to be burning deep into the peat. Several smaller sporadic fires were seen along the south-east coast, still smoking. In particular a large area near the albatross colony was burning steadily into the peat.

Upon landing, the team split into two groups, one aiming to assess damage to the Tussac grass and inspect prion and petrel burrows, whilst the other focussed on the Black-browed albatross and Rockhopper penguin colonies.

On each pedestal 50% of the tussac stalks were burnt and will probably die

From the landing site at the south-western end of the island at approximately 100m above sea level, both teams made their way along the south-eastern coast. The assessment was limited to two hours due to helicopter logistics and therefore was concentrated in the fire-damaged areas. The north-western slopes appeared to have received very little damage as a result of the fire. Only very small scorched patches were visible at the top of the ridge where the fire had spread over from the south and where the fire had initially started. Unfortunately this unaffected area is also the least ecologically valuable, being thin soils and grassland cover and shale slopes with little or no tussac grass (Strange 2001). The majority of the island's tussac was formerly found on the eastern and burnt south-eastern slopes.

The majority of the south-eastern side is blackened and parched, however there is evidence that the fire swept quickly along in some places, leaving almost intact tussac stools but removing both green and dead leaves. Many pedestals were very fragile and easily broke away, where the fire had burnt in and weakened the surrounding peat.

Aidan Kerr estimated that 90% of the tussac on the south-eastern side of the island had been destroyed. This comprised the majority of the tussac cover on the island. The remaining 50% had 10-30cms stalks of green leaf, but were not showing any sign of re-growth (1 month after the fire). Most leaf tips were singed. The only untouched area of tussac was found to the flatter, south-west end of the island, around the pond and below the 50m contour.

Some wild celery was growing on the bare peat in between the Tussac pedestals. These were small seedlings and may have regenerated since the fire. Some ferns, both small and tall fern, were showing signs of re-growth, however the majority of ferns were burnt down to the trunk beyond any chance of recovery.

Further along the south coast, the fire is still steadily burning within 100m of the albatross colony. This has produced 3-4 metre high banks, which have already burned in 5-10 metres, producing the same width of ash and leaving hot pits of ash up to 3 metres deep. The peat at these points has been completely destroyed and may be prone to erosion.

Breeding bird assessment

These fires are likely to burn for months or even longer

A full count of the Black-browed albatross Diomedea melanophris was carried out at the colony on the south coast. In November the albatross census covered this colony and 1745 nesting pairs were present (N. Huin pers comm). In this survey we estimated the total chicks remaining in the colony to be 845 (Actual counts 830 (Becky Ingham) and 860 (Nicolas Huin), directly comparable to those figures found by Strange (2001). Birds at the site appeared healthy and chicks were well developed. There were no traces of dead birds or chicks around the colony. Around the edge of the colony, breeding failure was higher. This occurs naturally within colonies, however may have been accentuated by the effects of the fire. The 71% success rate quoted by Strange (2001) is likely to be far higher than that actually achieved, as the nests examined were from inside the colony and did not take into account the effect of this lower success rate achieved on the perimeter. From the actual counts obtained in November and the number of chicks still alive within the colony, it would indicate that the breeding success is 49%, within the expected range for this species, although lower than that found in the islands in the previous 2 years.

The Rockhopper penguin Eudyptes c. chrysocome numbers were estimated at between 100-200 chicks, all nearly fledging. The large variation was due to the rocky nature of the colony and the tendency for creched chicks to gather together in hollows, however it is not considered that more than 200 Rockhopper chicks were present, lower than that found by Strange (2001). This reflects a breeding success of 0.25 chicks per breeding pair at best, and 0.11 chicks per breeding pair at worst, significantly lower than that found for other colonies in the Falklands this year (0.45 - 1.03, A. Clausen pers comm). This is, however, still better than the complete failure that could have occurred as a result of the fire. Twenty breeding King cormorant pairs were also seen in the main colony.

Burnt and blackened nests were common around the periphery of the colony

Many dead prion and petrel chicks were found in the burnt tussac pedestals all along the south coast. One badly burnt chick (possibly a storm petrel) was found in the top of a tussac pedestal, while other dead prion chicks were found lower down in the pedestal, probably having died of starvation rather than burning as they were down-covered and remained intact. This may have been as a result of abandonment due to extreme disturbance by the fire and fire-fighting activity or the death of the parent birds. Another unidentified nest containing two burnt eggs was also found toward the western end of the south coast. This was found in an area where it would appear the fire had passed through quickly leaving the tussac pedestals intact though blackened - in other areas there would be no chance of finding remains as the entire habitat including nests had been destroyed, leaving only the black trunks of tussac plants.

Many scorched bones of small birds were seen throughout the tussac along the entire southern coast of the island, as previously noted by Strange (2001). These may not have been a result of the fire, but equally this can not be ruled out, as not all these bones appeared to be old.

No Magellanic penguins were seen on the south coast, however there was evidence of burrows that had been occupied this season. It was not possible to estimate the damage to the population of Magellanic penguins at the eastern end due to time constraints. No other types of live burrowing species were observed on the southern slopes. Whilst no dead birds were seen either, this is not surprising a month after the event, with scavenging birds such as the Striated caracaras and Turkey vultures present on the island. Many juvenile Striated caracara Phalcoboenus australis were seen, approximately 12 concentrated on the southern coast around the observers and also 2 adults which may have been the breeding pair referred to in Strange (2001). Several Tussac-birds Cinclodes antarcticus were noted, as was a Cobb's wren Troglodytes cobii near to the albatross colony. Some Snipe Gallinago gallinago were also seen.

Summary

Compared to the state of the island before the fire, the loss of Tussac grass is undoubtedly dramatic and although re-growth is possible, it has not yet begun. The albatross colony was clearly extremely fortunate that the fire did not burn into the centre of the colony, probably because of the naturally damper and barren conditions prevailing there. There was much evidence that many nests surrounding the colony in the Tussac fringe had been burnt - these were empty. Some chicks had been clearly killed around the edges, but this is relatively minor. Breeding penguins also appear to have suffered minimal losses in numbers, but a very low breeding success. Rockhopper breeding success has been very low across the entire archipelago this year however, and it is likely that the low success rate seen here is not purely a result of the fire.

The major environmental impact to the island was the loss of un-quantified numbers of prions, petrels and other species within the Tussac such as Snipe, Cobb's wren, Grass wren, Falklands thrush and petrel species, which would have been burned as the fire passed through the tussac. It would seem that some chicks of these species died both during the fire and afterwards as a result of abandonment.

The main concern is now the steadily burning banks of Tussac peat on either side of the colony on the south coast. Even if these are extinguished naturally by bad weather in the winter months, the damage to the leaf cover has been done and soil erosion will probably occur, particularly where ash is unstable on steeper slopes.

It is recommended that the fires still burning on the island are checked regularly to ensure that the peat banks burning in the centre of the south-eastern slopes and the extreme north-eastern tip of the island do not spread to other areas.

Acknowledgements

Our thanks to the Sea King crew from 78 squadron and Commander Colin Martin, Head of Operations, who enabled us to get to the island and to the Falkland Islands Government for permission to visit.

R. Ingham
A. Kerr
A. Henry
N. Huin

14 Feb 2001