Nycticorax olsoni N. P. Ashmole, K. E. L. Simmons & W. R. P. Bourne

Ascension Island Night-Heron (Nycticorax olsoni)  

This species of night-heron was described in the year 2003 based on subfossil bones, which were found in guano deposits. In live this species was somewhat smaller than the Night-Heron (Nycticorax nycticorax (L.)), and it was most probably a weak flyer but not fully flightless.  

The Ascension Island Night-Heron may have stayed near the coast, where it searched the giant sea bird colonies, existing on the island at that time, for unattended fledglings, resp. fished for crustaceans at the shore.  

The species reached a length of about 50 to 60 cm.  

The circumstances of its extinction are not known, but introduced rats may well have played a role as they did in so many other cases of extinctions of birds on islands.  


In chapter 21 (D’une isle nommée l’Ascention.) of his book ‘Les singularitez de la France antarctique, autrement nommée Amérique, et de plusieurs terres et isles découvertes de nostre tems.’ from the year 1557 André Thevet describes a bird from Ascension Island which indeed could well be the Ascension Island Night-Heron.:  

Dauantage en ceste isle s’en trouue une espece de grands, que i’ay ouy nommer Aponars. Ils ont petites ailes, pourquoy ne peuuent voler. Ils sont grands et gros comme noz herons, le ventre blanc, et le dos noir, comme charbon, le bec semblable à celuy d’un cormoran, ou autre corbeau. Quand on les tue ils criênt ainsi que porceaux.”  


Furthermore in this Ilande there is a certayne kinde of greate birdes that I have heard called Aponars, they have little wings, and therefore they cannot flye. They are great and hye lyke hearnshawes, the belly white, and the backe blacke as cole, the byll lyke to a cormorant, or a different crow. When they are killed they crye lyke hogs.”  [1]


The Ascension Island Night-Heron very likely disappeared shortly after.  



[1] A. Thevet: The new found worlde, or Antarctike. London: Henrie Bynneman for Thomas Hacket 1568


edited: 20.10.2016