 |
 |
 |
 |
||
 |
||
 |
 |
|
 |
Rosa Pires & Henrique Costa Neves We wish to thank all those who, in any way, contributed to the development of this project, including the Nature Wardens of the Parque Natural da Madeira, and also the European Community for their financial support. Bareham, J.R. & S.J. Furreddu. 1975. Observations on the use of grottos by Mediterranean Monk Seals (Monachus monachus). Journal of Zoology, London 175: 291-298. Trotignon, J. 1982. Les derniers phoques sahariens. Courrier de la Nature 77: 14-20.
DESERTAS ISLANDS – MADEIRA ARCHIPELAGO
Parque Natural da Madeira
Caminho do Meio, Quinta do Bom Sucesso, 9050 Funchal, Portugal
The Mediterranean monk seal has been persecuted by humans for centuries, forcing the species to change some of its habits and behaviour in order to survive. This is particularly evident in its choice of habitat. Looking for security, the seals started to use only the beaches inside of caves to rest and to breed, instead of open beaches (Bareham & Furreddu 1975, Sergeant et al. 1978, Machado 1979, Trotignon 1982, Marchessaux 1989, Brasseur et al. 1997, Johnson & Lavigne 1999).
Nevertheless, observations of monk seals on open beaches have recently been made on the Desertas Islands, nine years after the start of monk seal protection efforts.
The Desertas Islands belong to the Madeiran archipelago and are located 11 miles SE of the main island (Madeira). Ilhéu Chão, Deserta Grande and Bugio comprise this sub-archipelago.
Most of the 37 km of its coastline is composed of steep inaccessible cliffs. In addition, there are numerous beaches and caves that provide ideal habitat for monk seal resting and breeding.
On the island of Madeira, the monk seal originally used open beaches and easily-accessible caves to rest and to breed (Machado 1979). However, this natural behaviour made the species vulnerable to human pressure. As a result, the population began to decline and eventually it disappeared from the island. Nowadays it is likely that only a few animals survive on the Ponta de São Lourenço, located on the extreme east of Madeira.
In practice, the Desertas Islands became the last part of the Madeiran archipelago with suitable conditions for monk seal survival. In addition to the excellent food resources, the seals found security in these uninhabited and isolated islands. Indeed, old fishermen would talk about the use of Desertas Islands beaches and caves by seals, a behavioural trait that was once also seen on the island of Madeira itself.
Sadly, this behaviour disappeared with the increase in fishing activity around the Desertas Islands during the 1970s. In particular, the fishermen became increasingly hostile towards the seals. It is unlikely to be coincidence that the seals were rarely seen again on open shores where they would have been at the mercy of fishermen.
As a result of both direct and indirect harassment, the population went into steep decline. In 1978, the estimated population size was 50 animals (Sergeant et al. 1978) but, by 1988, the numbers had dwindled to only 6-8 individuals.
Given these circumstances, there was clearly an urgent need to develop and implement a strategy to preserve the monk seal. A programme to protect this species was initiated in 1988 and, by 1990, the Desertas islands were legally protected.
The strategy developed to protect the monk seal was a combination of management actions and scientific initiatives. On the management side, the main approach was to patrol the islands by boat, in order to ensure effective protection of both the seals and their habitat. Simultaneously, a monk seal monitoring programme was established in order to determine the status of the population and to obtain a much better understanding of the biology and ecology of the species. Such knowledge is essential to find the best strategies to conserve the monk seal in a real situation.
With such an endangered population it is very important that the monitoring methodology be as non-intrusive as possible.
Fortunately, the geography of the island enabled us to establish lookout sites along the 3 islands. From here observations can be documented and photo-identification studies conducted.
During last 8 years, almost 4000 hours have been spent patrolling the islands by boat and just over 5000 hours occupying the lookout sites. In other words, we have averaged about two and half hours of observation effort per day.
As a result of the work that has been done, we have managed to eliminate the major direct impact on the population – fishing activity. In fact, there is now very little human disturbance on the Desertas Islands. In addition, we have made some 670 sightings of monk seals over the period, which is very significant for a population so small, and which is providing a sound basis for monitoring the status of the population.
One of the most exciting developments was that in 1997, we saw monk seals on the shore of the Desertas Islands for the first time in many years. For almost 20 days, two females, "Bi-risca" and "Desertinha" used Tabaqueiro beach to rest and to suckle their pups (Fig. 1 & 2).
Fig. 1
Fig.2
This beach, on the extreme SE of Deserta Grande, is very close to the cave in which most of the births have occurred. This seems to be the primary area used by monk seals during the reproductive season.
Monk seals were seen on shore again in July 1999, also on the SE of Deserta Grande. However, this time the sighting was on Areias beach, where a juvenile, recognised as "Bi-risca´s son", and an immature seal were observed at rest. During recent years we have noted that activity associated with monk seal breeding behaviour has mainly taken place in this area (Pires 1997).
A few months later in December, the same reproductive females with new pups again used Tabaqueiro beach in addition to the cave, and this time for a longer period. They used this site to rest and suckle for almost 2 months. In general, the animals sporadically use this as a place to rest.
It is significant that the seals only started to use open beaches 9 years after the start of the protection programme, in other words, 9 years after the cessation of human persecution on the islands.
Although it has taken a long time, the seals are now beginning to use the open beaches during the breeding period when they are at their most sensitive. Last year the time spent on the shore by the seals increased considerably. In addition, new individuals are showing a tendency to use the Desertas Islands’ open beaches.
We view this as exceptionally positive news. It demonstrates that the seals are gradually reacquiring a sense of security on the Desertas Islands and consequently returning to their natural and original habitats and behaviour. This and the recovery of the population that we are assisting is a promising sign for the future of this species in the Madeira archipelago.
Acknowledgements
References
Brasseur, S.M., P.J. Reijnders, & G. Verriopoulos. 1997. Mediterranean Monk Seal, Monachus monachus, pp.12-26 in: Status of Pinnipeds relevant to the European Union (eds. P.J. Reijnders, G. Verriopoulos & S. M. Brasseur). IBN Scientific Contributions 8. DLO Institute for Forestry and Nature Research (IBN-DLO), Wageningen: 1-195.
Johnson, W.M., & D.M. Lavigne. 1999. Monk seals in antiquity. The Mediterranean monk seal (Monachus monachus) in ancient history and literature. Mededelingen 35: 1-101. The Netherlands Commission for International Nature Protection.
Machado, A. 1979. Os Lobos marinhos (Género Monachus, Fleming 1822): Contribuição para o seu conhecimento e protecção. Câmara Municipal de Cascais, Museu do Mar: 1-237.
Marchessaux, D. 1989. Recherches sur la biologie, l'écologie et le statut du phoque moine, Monachus monachus. GIS Posidonie Publ. ISBN Nº2-905540-13-3, Marseille, France: 1-280.
Pires, R. 1997. Estado actual e aspectos da biologia e ecologia da colónia de lobos marinhos, Monachus monachus, das Desertas Islands. Relatório de estágio para ingresso na carreira técnica. Secretaria da Agricultara Florestas e Pescas, Parque Natural da Madeira, Funchal.
Sergeant, D., K. Ronald, J. Boulva, & F. Berkes. 1978 The recent status of Monachus monachus, the Mediterranean monk seal. Biological Conservation 14: 259-287.
Copyright © 2000 R. Pires, H.C. Neves, The Monachus Guardian. All Rights Reserved