Largest rat eradication in South America - ever!

(from the Galapagos National Park News service)

The Galapagos National Park Service, with the support of the organization Island Conservation, Charles Darwin Foundation, The Raptor Center at the University of Minnesota, Durell Wildlife Trust and Bell Laboratories, began implementing a massive ecological restoration project by removing introduced rodents.

This ambitious plan, developed for the first time in South America, in a first phase, focuses on the total eradication of introduced rats and mice on small and medium-sized islands of the Galapagos.   In a pilot project in 2008, all rodents were successfully eradicated from the 184 ha North Seymour island, a popular visitor site where frigates can be seen nesting, and large land iguana's roam.    

Next on the Park's target list are Rabida, Bartolome, Sombrero Chino, North Plaza islands (all visitors sites). 

Successfully getting at every last rat and mouse on a large island is not easy.   Poisoned baits will be distributed aerially via a helicopter mounted mechanical bait dispersal mechanism.  Lessons learned in the pilot project will be applied - such as distributing baits at 7 day intervals, to ensure that rats too young to consume them in the first dispersal, are old enough to do so at the second dispersal. 

The helicopter is equipped with a high precision GPS, allowing the pilot adequate control of the flight and therefore ensuring that no square metre of an island is left out.

Rat eradication helicopter

Before applying the product, as part of this plan, risk analysis was performed on non-target species such as hawks, finches and mockingbirds, to determine possible effect on these species.   The Park learned that the species at highest risk was the hawk, as it may capture and feed on rodents that have consumed the bait.   Adequate measures to avoid this eventuality were needed.   These consisted of live capturing hawks, and keeping them in cages specifically designed to hold them under optimal conditions, during the rat baiting periods.  

Rodents in Galapagos

  • In the Galapagos there are 3 types of introduced rodents: the black rat, Norway rat and house mouse.
  • Rodents have caused adverse effects on reproduction of tortoises, iguanas, land and sea birds, especially on the Galapagos petrel, which nests in the wetlands of the larger islands.
  • Unless rodents are completely exterminated, their negative effects can never be sufficiently controlled, and vulnerable Galapagos wildlife will remain at risk.

Because native animals of Galapagos arrived only by successfully crossing 1,000 km of open ocean, very few mammals are native to the islands.  Only 2 bat species and one native "rice rat" .