IUCN threat status:

Critically Endangered (CR)


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Range Description

Corvus kubaryi inhabits Guam (to U.S.A.) and Rota in the Northern Mariana Islands (to U.S.A.). On Guam, it was formerly common but, since the 1960s, declined in numbers and area inhabited, with an estimated 350 birds in 1981 (Engbring and Pratt 1985), fewer than 40 in 1995 (Fancy et al. 1999), and 7 in 1999. Following introduction of birds from Rota the population rose to 16 in 2001 (G. Wiles in litt. 1999), but had declined again to two (both male) by 2008 (R. Berry in litt. 2008). The most recent sighting on the island was in 2011 and the species may now be extinct on Guam (F. A. Amidon in litt. 2012). On Rota, the population was thought to be stable at 1,318 birds in 1982 (Engbring et al. 1982), but has since declined to 592 in 1995 (Fancy et al. 1999), and then to 234 in 1998 (Morton et al. 1999, Plentovich et al 2005); in 2007 there were c. 50 confirmed pairs and a few more suspected (G. Rodda in litt. 2007), and the population in 2008 stood at around 85 pairs (Amar et al. 2008). One bird remains in captivity (J. Morton in litt. 2000, F. A. Amidon in litt. 2012). Surveys on Rota between 1982 and 2004 indicated a decline of 93% (Amar et al. 2008). Apparent survival analysis of birds ringed between 1990 and 2010 revealed that the rate of first-year survival fell from 70% to 40% over that period, roughly equivalent to a doubling in the rate of mortality; this was accompanied by a slight decrease in adult survival over the same period. Population modelling using the most recent estimate for apparent survival in first-year birds predicts extinction of the species in 75 years, with models that incorporate the removal of birds for captive breeding and the impact of catastrophic events projecting more rapid declines (Ha et al. 2010).


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© International Union for Conservation of Nature and Natural Resources

Source: IUCN


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