Having spent close to three months on Nightingale and then Tristan da Cunha Islands last year I was struck by the incredible seabird diversity on the uninhabited and much smaller island of Nightingale. As many as 13 different seabird species breed on the 3 square kilometre volcanic island with a highest point of 400 m above sea level.
Not too far away is the massive island of Tristan at over 200 square kilometres in size and a highest elevation of 2000 m above sea level yet almost no seabirds breed there except for the ubiquitous Yellow-nosed and Sooty Albatrosses. Tristan is inhabited and has rats. Nightingale is uninhabited and has no mice or rats. Most of us are aware of the damage done by mice on Gough Island. It is therefore vitally important that Nightingale and Inaccessible remain rat and mice free islands. What these islands show is the harsh reality of one system in an almost pristine state (Nightingale) compared to another that has undergone so many significant changes and impacts (Tristan) that it may never return to any near its original state of affairs.
Nightingale may seem small but it has as many as 3 million pairs of Great Shearwaters alone that breed there every year. Add to this 100 000 Broad-billed Prions and a few thousand pairs of the Endangered Atlantic Yellow-nosed Albatross and one immediately realises the significance of the island from a seabird conservation perspective. Possibly of most importance is the largest Northern Rockhopper Penguin colony in the world that can also be found there.
Nightingale provides us with some insight into what Tristan may well have been like before humans settled. The size of Tristan and the massive change in altitude from the coast to the highest point would suggest that almost every species of seabird that breeds in the Southern Atlantic on Gough, Nightingale and Inaccessible may well have occurred and bred on Tristan historically. Of course the critically endangered Tristan Albatross is just one example of a species that is extinct on the island and currently Atlantic Petrel breeds only in very low numbers!
I for one hope that if I have the privilege of ever visiting Nightingale again that the many thousands of seabirds will still be there without the significant risk of predation by introduced mammals such as mice and rats that have devastated so many island species communities around the globe.
To illustrate the impact of rats I have added a link below to a recently published video of a Black Rat feeding on a Scopoli’s Shearwater chick courtesy of Francesco Di Pietro: http://www.youtube.com/watch?v=y0BeiWJeOPo The footage is taken from Pianosa Island (Tuscan Archipelago, Italy).
Below: Soft plumaged Petrel on Nightingale Island
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