109 species of flowering plant that used to grow on the Maltese islands are thought to have become extinct in the last century.

And another 80 flowering plants are endangered, 44 are vulnerable, 136 are rare and the status of 38 others is as yet to be determined.

These details are contained in a list of extinct and threatened species of the Maltese islands which includes beetles, butterflies, moths, birds and mammals.

The list forms part of the Malta national report submitted by the government to the World Summit on Sustainable Development being held in Johannesburg.

The list is based on an update of the first Red Data Book for the Maltese Islands edited by Patrick J. Schembri and Joe Sultana and published by the Department of Information in 1989.

Prof. Schembri, a biologist, said the listed flora and fauna were threatened in Malta and some were also in danger elsewhere.

The list is based on criteria devised by the International Union for the Conservation of Nature and Natural Resources, now called the World Conservation Union.

"The list is an international benchmark on how to rate the level of threat faced by flora and fauna.

"There are various levels of threat: from the highest to the lowest. The lowest refers to 'indeterminate', which means that although biologists suspect there is a threat, not enough data are available to quantify the threat.

"'Endangered' means the species will become extinct if it remains subjected to the current adverse conditions.

"We adapted this international benchmark for Malta which means that where we are saying a species is extinct we mean it is extinct from the Maltese islands," he said.

But how does one arrive at the conclusion that a plant, an insect or a mammal is extinct?

"In most cases, we base this on the reports of experienced field naturalists. For example, in the case of plants, one would rely on botanists who have been studying local flora for years and who know where to search for rare plants.

"If such botanists tell you they have not come across a particular plant, let's say for the past 20 years, then there is a good chance that it has become extinct.

"Technically, such a conclusion would be arrived at by carrying out scientific surveys in the wild but one cannot do such a thing for all the species unless one has huge resources.

"We conduct such surveys only when we find out that a particular species seems to have died out over the past few years.

"For example, we have carried out surveys in the habitats where the freshwater crab, il-qabru, used to live. We know that the crab has disappeared from several valleys where it used to be found previously."

Il-qabru (plural qwabar) is the crab appearing on the 5c piece.

An example of a vulnerable species is the Maltese top-shell, a sea snail known as Gibbula ta' Malta. The snail is endemic. A lot of its shells can be found in many bays but the live species has recently only been found in two places and it is becoming even rarer.

"While we know that the freshwater crab is threatened because of the loss of its habitat, we do not know the reason behind the disappearance of the top-shell."

The whole exercise is carried out so that the authorities in charge of the protection of the environment can take the measures necessary to mitigate the negative impact on such species.

The list is a tool, not an end in itself, which would help the authorities decide where to place their priorities depending on the scale of the threat.

"The Maltese wall lizard is endemic, that is, it only exists in the Maltese islands and nearby Linosa and Lampione but over and above this, islands within the Maltese archipelago, such as Filfla, il-Gebla tal-General and St Paul's Islands, have their own endemic race.

"While the Maltese male lizard is green with yellow under its neck, the Filfla lizard is black with blue spots. These races of lizard are endangered because they live in an extremely limited space. For example, if a catastrophe, such as a fire, breaks out on one of the smaller islands such a race could die out," Prof. Schembri explained.

Another endangered species is the endemic Maltese door snail, a land snail known as Dussies ta' Malta -dussies means spindle.

"It is found in only one habitat that covers an area of just a few square metres with an extremely small population. If that habitat is destroyed, then the snail would be wiped out from the face of the earth forever," he said.

What does this all mean for the man in the street?

"If we are proud of our prehistoric temples, of our architectural heritage and of our language because they give us our identity, then we should be proud of the species that are only found in these islands and which also form part of our national patrimony.

"Apart from this, such species form part of one ecosystem. In nature they have a function, even if we do not exactly know what that function is. The main threat is the destruction of habitat.

"Another threat is the introduction of alien species, a prime example of which is the cape sorrel - the Haxixa Ingliza. Originally, the sorrel was brought into Malta as a botanical specimen for the Argotti Gardens, in Floriana, from where it has spread all over the islands. The same applies to other plants that propagate easily," Prof. Schembri said.

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