RESEARCH PUBLICATIONS

TABLE 1: Breeding success over the last 8 years (2000 to 2007)

Data source: © Mike Bingham, Organization for the Conservation of Penguins, 

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Comparison of nests alongside the tourist path, with nests in the study plots which are away from tourists (Table 1), shows a slightly higher breeding success for nests close to tourists (near to tourists = 1.17 chicks per nest / not near tourists = 1.10 chicks per nest). With only eight years of data, such a small difference may not be statistically significant, or it may be that predators of the penguins' eggs and chicks, principally skuas, tend to stay away from tourists, reducing the amount of predation on penguin nests near to the tourist path. What is apparent is that these penguins readily adapt to the presence of tourists, and are comfortable with the current level of tourism on Magdalena. Comparing the weight at fledging between the chicks raised within the tourist area and those raised in areas not visited by tourists, our data over a six year period (2002 to 2008) show tourist path chicks to be slightly heavier (average weight over six years = 3.34 kg) than non tourist areas chicks (average weight over six years = 3.31 kg), although the difference is so small that it is not statistically proven.
With respect to the effect of human disturbance on the behavioural pattern of penguins, our study indicated that Magellanic penguins show a differential behavioural response according to their exposure to people. Magellanic penguins on the tourist trail and in the tourist area allowed a closer approach to their burrows before responding than birds nesting in undisturbed areas where tourists do not visit. Some penguins nesting close by the tourist trail were almost indifferent to people approaching them to within 0.5m, and remained resting with their eyes closed after seeing the visitor. Rarely penguins fled their burrows in close human presence (distance <2m). Only when many penguins were gathered together did they flee when being approached, which is probably due to the high level of group stress. In addition to group stress, another factor of relevance in their flight response is that the birds are not protecting nests. Even single birds not on nests will run, whilst penguins on nests (including open nests) generally do not. In contrast to the tourist areas, penguins nesting in undisturbed areas responded at a greater distance and with more pronounced behaviour. Penguins fled their burrows at a distance of 25m, or moved very nervously within the nest site; penguin alarm calls signalled the presence of an intruder at > 30m distance. These behavioural patterns suggest that penguins that are not used to people are more stressed by occasional visitors.
In essence, penguins breeding in the tourist areas showed a significantly weaker behavioural response to approach then penguins nesting in undisturbed areas. The variation observed in the behavioural response of Magellanic penguins according to the amount of human disturbance is similar to observations made in other Magellanic penguin colonies in Patagonia (Yorio et al., 1998; Cevasco et al., 2001) and among other penguin species, e.g. Jackass penguins in South Africa (van Heezik & Seddon 1990).
Annual monitoring of breeding success did reveal one area of concern for the future of penguins on Magdalena Island. During the 2002/03 season, breeding success was very low indeed, averaging just 0.42 chicks per nest, which would be insufficient to maintain the population if such conditions persisted. During the summer of 2001/02 virtually no rain fell on Magdalena Island, and as a result most of the grass on the island died. As a result by the 2002/03 season the island had lost most of its vegetation and was mostly covered in bare earth. The strong winds which always prevail in this area blew the loose earth across the island day after day, and by December 2002, most of the penguins' nests had been abandoned as a result of eggs and small chicks being buried in these dust storms. Fortunately 2002-03 was a fairly wet season, and by 2003-04 much of the vegetation had returned. However this incident does show just how fragile the penguins are to any climate change that reduced rainfall on Magdalena.
Comparison of breeding success of nests in burrows and nests out in the open revealed surprising results. Most penguins on Magdalena Island nest in burrows, but a few penguins lay their eggs out in the open without the protection of any burrow. Most of these open nests become abandoned, suggesting that they are much less successful than nests in burrows, but that was not the case. Most open nests survive during the egg incubation period, and whilst the chicks are small and well protected by the parent, only to become abandoned when the chicks are left alone by both parents. However these nests mostly become abandoned not through the chicks being taken by predators, as had been assumed, but by the chicks leaving their open nest in search of a neighbouring unoccupied burrow.
During 2001/02 breeding success for nests in burrows was 1.38 chicks per nest, and 1.06 chicks per nest for open nests, even though virtually all open nests had been abandoned (Table 1). This was largely the result of chicks seeking out the protection of nearby vacant burrows, rather than actual chick loss. Whether open nests are less experienced pairs, pairs that arrived late, or simply pairs that are cheating the system, is unclear. However only a small proportion of the colony can make use of this system, since they rely on occupying burrows built and subsequently abandoned by other penguins in order to avoid loosing their chicks.
Annual counts of juveniles on the island conducted between 2000/01 and 2006/07 show that only a small proportion of Magdalena's juveniles return to the island prior to reaching maturity. Annual counts average around 3,000 juveniles per year, which is considerably fewer than would be required to maintain a stable population. Assuming a population of 60,000 breeding pairs, an active breeding duration of 15 years (aged 5 to 20 years), and a juvenile phase of only 3 years duration, a total of 24,000 juveniles would be expected on the island each year in order to provide a stable population. Since the population on Magdalena Island is actually increasing in size, the total number of juveniles surviving must be even greater, and yet the number actually counted on the island is very much less. Therefore it must be concluded that the great majority of surviving juveniles do not return to Magdalena until they reach maturity and begin breeding.

CONCLUSIONS

Annual monitoring shows that penguin populations on Magdalena Island are healthy and increasing, and that Contramaestre Island is being colonised by penguins spilling over from Magdalena Island. Breeding success is high, egg and chick losses are low, and chicks are healthy and very well fed, suggesting high juvenile survival after leaving the nest.
Tourism appears to be having no negative effect on penguins at the present level, penguins breeding in the tourist areas are accustomed to people walking among their nests, and tourist visitation did not decrease breeding success. Penguins breeding in the tourist area show a significantly weaker behavioural response to approach than penguins breeding in undisturbed areas. Tourism seems to be compatible with penguin reproduction provided that tourists remain within a set path. Given the rising number of tourists visiting the colony, careful management of tourist areas in the penguin colony on Magdalena Island must continue, allowing the development of tourism whilst protecting the Magellanic penguin colony. Further data are needed to continue evaluating the effects of tourist visitation. Tourism may possibly be having a slightly negative effect on skuas.
Oil spills from passing maritime traffic through the Straits of Magellan, and the Cabo Negro facility, is a constant threat that could seriously damage the colony at any time in the future without warning. There is also strong evidence that if annual rainfall were to become reduced on Magdalena Island, as a result of climate change, that it is likely to have a serious effect on the penguins on Magdalena Island.

ACKNOWLEDGMENTS

Our special thanks go to the Chilean National Forestry Corporation (CONAF) and the rangers of Magdalena Island (Domingo, Floridor, Louis, Neftali, Roberto, Luis) for their continuous help. We are very thankful to the crews of Melinka, Fueguino, Mare Australis, Tierra Australis, Via Australis, Don Jorge, Hundy, Mandamiento and Solo Expediciones for their logistical support. Mike Bingham would like to thank his research assistants Nidia Mendez, Elena Mejias, Cici Legoe, Christopher Burney, Jennifer Rock, Jon Philipsborne and Joseph Brandt . Financial support was kindly provided by the Darwin Initiative (British Government), ENAP, the Canada Research Chair in Ethnoecology and Biodiversity Conservation, and members of the OCP's penguin adoption programme.

LITERATURE CITED

Bertea, L. & Herrmann, Th.M. (in press) El Pingüino de Magallanes: Colonias del Estrecho de Magallanes - Magellanic penguins: Colonies in the Strait of Magellan - Der Magellanpinguin: Kolonien in der Magellanstrae - Le manchot de Magellan: Les colonies du d‚troit de Magellan. Editorial Patagonia Interactiva, Chile, 120 p.

Bingham, M. 1998. Penguins of South America and the Falkland Islands. Penguin Conservation 11(1): 8-15.

Bingham, M. & E. Mejias 1999. Penguins of the Magellan Region. Scientia Marina Vol:63, Supl. 1: 485-493

Bingham, M. 2002. The decline of Falkland Islands penguins in the presence of a commercial fishing industry. Revista Chilena de Historia Natural 75: 805-818

Bingham, M. 2004. Seabird Monitoring Instruction Manual for Magdalena Island. Organization for the Conservation of Penguins, 22pp.

Cevasco, C., E. Frere & P. A. Gandini 2001. Intensidad de visitas como condicionante de la respuesta del pingüino de Magallanes (Spheniscus magellanicus) al disturbio humano. Ornitologia Neotropical 12:75-81

Gandini P., E. Frere & D. Boersma 1998. Status and conservation of Magellanic Penguins in Patagonia, Argentina. Bird Conservation International.

Hiscock, K. 1993. A manual for marine biological inventory surveys. Joint Nature Conservation Committee Report MNCR/OR/19

van Heezik Y., & P.J. Seddon 1990. Effect on human disturbance on the breeding behaviour of Jackass Penguins. South African Journal of Wildlife Research 20: 89-93

Yorio P. & D. Boersma 1992. The effects of human disturbance on Magellanic Penguin Spheniscus magellanicus beahaviour and breeding success. Bird Conservation International 2:161-173