Rat eradication from Monte Cristo Island: biodiversity conservation or ecological disaster?

They are numerous conservation projects annually activated with the aim of protecting a specific animal or plant species. However, this often happens to the detriment of others, or even to the detriment of the whole local biodiversity. This appears to have occurred in the context of the Life project, which was aimed at 2012 eradicating the black rat from Monte Cristo Island promote conservation less shear watera seabird that nests on an island.

Dr. Rosario Ficopresident of the Italian Society of Veterinary Forensic Sciences and then head of the National Reference Center for Veterinary Forensic Medicine of the Experimental Zooprophylactic Institute of Lazio and Tuscany, spoke about the conference “Management of the Italian Natural Heritage of the Last Decades” held last May with technical considerations of considerable importance that they help to understand across the spectrum what could have happened and how human intervention could have been destructive to ecosystems.

Montecristo Island

Monte Cristo Island

The island of Montecristo is one of the most important islands in the Tyrrhenian Sea and belongs to it Tuscan Archipelago National Park. The island is a protected area to protect its biodiversity, whose fauna is great naturalistic interest and which includes a species of wild goat whose population is only found on the island, the Montecristo goat. The bird population is also of great importance, among which are numerous species of songbirds, rock partridges, numerous pairs of herring gulls, common ravens, barn owls and other diurnal and nocturnal predators that occur mainly during migrations.

The large population is also of great importance less shear waterwhich represents one of the five most important in Italy and which (already before the Life project) was among 3 and 10% of the world population this animal. In addition to mammals and birds, there are various species of reptiles, including the rat and viper, and amphibians such as the discoglossus, and numerous species of invertebrates.

Life+ Montecristo 2010 project

On the island, black rat is considered a threat to the breeding success of the Shearwater colony. For this reason, the project was financed in 2010 Life+ Montecristo 2010aimed at preserving shear water through eradication of the black rat. In order to eradicate rodents, grain pellets containing Brodifacoumone of the most potent toxic anticoagulants known to be highly persistent in the environment.

Distribution affected the entire surface of the island (approx. 1,350 hectares) for a total of approx. 14 tons of pellets (on average 10.3 kg/hectare) distributed by air using helicopters. In a small populated area of ​​approximately 30 hectares, the pellets were instead distributed via special containers.

Areas where the pellets did not reach was a section including the main freshwater stream of the island and a fenced area of ​​25 hectares where a group of approx. 45-50 copies of Montecristo goats. Thus, the area not affected by the spread of Brodifaco was only 33 hectares out of a total of 1350. In order to establish an ex situ conservation core of feral goats, the project also relocated a group of five individuals to the Bioparco in Rome.

The catastrophic effects of toxic proliferation for Project Life

Monte Cristo Goat

Brodifacoum is technically classified as toxic, bioaccumulative and persistent substance. In fact:

  • is one of more toxic anticoagulants which when ingested in lethal doses causes internal and external bleeding leading to death and which can cause spontaneous abortions, fetal toxicity and impaired immune system efficiency in mammals when ingested in sublethal doses;
  • has a peculiarity stay in the organism victims, living or dead, for many months, even at sublethal levels, allowing it to bioaccumulate;
  • it’s extreme persistent in the ecosystem because its molecule, once released into the environment (also after the physical breakdown of the pellets), binds for a long time to numerous organic substrates contaminating its biological components.

The dispersion of thousands of kilograms of toxic substances into the environment by air inevitably causes the death of peoplen large number of non-target species intervention in both primary poisonings (direct ingestion of granules) and secondary poisonings (ingestion of prey, remains of dead or contaminated animals with sublethal doses and their droppings).

The victims of Brodifacoum in Montecristo were actually species of mammals, incl the Montecristo goat and the wild rabbit, birds, invertebrates and reptiles. At the level of the marine ecosystem, serious risks were also predicted, as Montecristo Island has high and steep walls that favorspilling into the sea unspecified quantities of pellets containing a toxic substance.

In fact Dr. Fico presents a hypothesis “which may seem bold” about the correlation between the unusual stranding of 122 cetaceans occurred on the Italian coasts in the first 3 months of 2013 (and never recurred), which, where tests could be carried out, was explained by a compromise immune system associated with an extraordinary parasite load and the presence of pathogens.

Did the eradication have the desired effects?

Red Shearwater in flight

Firstly, Dr. Fico makes us think about it possible project startup erroror the identification of rats as the main cause of the lack of reproductive success of shearwaters, «a conclusion that is not easy to draw without the use of a method that allows the loss of an egg or chick to be unequivocally attributed to predation».

“Insular seabird populations are actually subject to significant annual fluctuations as a result many factors, especially climatic and ecological, whose interactions are very complex. In addition, the island is characterized by steep cliffs, cliffs and poor vegetation cover, which offer nesting sites for seabirds in deep and winding hollows in almost vertical areas. not very accessible to rats» explains Dr. Fico.

The expert also underlines the frequency of project effectiveness studies critical points which can be summarized as follows:

  • the effectiveness of the interventions was assessed little tracking conducted on a small percentage of Shearwater nests, as well as only on nests located in areas accessible to researchers;
  • monitoring was done in limited periods of timewhile they were to be carried out on the total bird population for several years, before and after the eradication intervention.

Speaking of numbers, the estimated pairs of Red Shearwaters on Molara and Montecristo Islands after Project Life were cumulatively between 500 and 600 pairswhile before the intervention only on the island of Montecristo were estimated 400-750 pairs. Numbers that are difficult to interpret to demonstrate the true effectiveness of the rat eradication operation.

In addition to the effects on the population subject to protection, the effect achieved on the target species should also be analysed, black rat. In fact, not all rats present on the island could be affected by the bait, leading to gradual repopulation guaranteed by survivors of the spread of the toxic substance. In addition, the reappearance of rats is also possible due to many other factors, the main of which is whether people carry them accidentally or not.

And from an ethical, social and legal point of view?

During the project implementation period, the 2010 Ministerial Decree “Regulation on the Prohibition of the Use and Possession of Poisoned Bait or Bait” was in force, which provides absolute ban on rodenticides with high resistance to the environmentas well as Brodifacoum.

Furthermore, a possible violation of article 544 ter of the Criminal Code due to the death due to primary poisoning of many specimens of the Montecristo goat, as well as many others non-target animal speciesand violation of Article 452 bis of the Criminal Code for the crime of pollution.

Deaths caused by hundreds of animals and contamination that likely based on global bibliography researched it will inevitably affect the entire ecosystem for yearsas a side effect of an eradication operation of questionable efficacy, it raises an ethical debate that is not easy to interpret.

For this reason, the project aroused a series of social protests and legal actions. There have been numerous protests by animal rights associations and private individuals that have resulted in court filings, including a former spearfishing champion, a native of Elba. Carlo Gasparriand in parliamentary matters, including the latter.

As the literature and other documented cases show, this is not the first episode of interventions unethical and dysfunctional ecosystem management by a man who acts like a Deus ex machina in deciding what is good or bad for nature, it causes more harm and less good.

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