Mariana Crow Recovery (David Gordon)

 

The mariana crow, also known as the Aga Crow (Corvus kubaryi), were originally found in Guam and Rota, however the last native crow from Guam is believed to have vanished in the early 2000’s. The crow tends to live in mature limestone forest, but can also be found around coastline, ravine, and agricultural forests as well as coconut plantations. 

Mariana Crow on Rota

This bird nests in the drier season, from September to March. The construction of their nest resembles a large platform supporting smaller “cups” made from sticks and vines found throughout the forest. Their nests have only been found in trees native to Guam and Rota. Mariana crows typically eat small invertebrates and fruit as their diet. 

Mariana crow chicks - Photo credit Mike Lusk/USFWS

As of May 2005, Ten crows are known to survive in the wild on Guam, however all of the individuals are known to have originated from Rota. As far as populations on Rota, there were believed to be 85 pairs of crows but with expectations for this number to decline.

Brown Tree Snake

The priority number for recovery for the Mariana Crow is 5C. This is measured on a scale of 1 to 18. This rating was found based on the fact that the Mariana Crow faces a “high degree of threat, low potential for recovery, and high potential for conflict with human activities (U.S. Fish and Wildlife Services).” The species was listed as endangered on January 11, 2006. In 2008 the species was reclassified as Critically Endangered. 

The reason for listing was a result of many external factors working against the Mariana Crow as a species. Habitat loss played a large role, however it was also accompanied by human persecution, diseases from introduced species like cats and rats, as well as nutritional factors. The leading cause however is believed to be the brown tree snake that was introduced to Guam. Rats are blamed as the leading cause for the eradication of this species on Rota. The main continued threats are the tree snake and predation from other species such as rats and cats. 

The current plan in action to help the species recover consists of several actions that need to be taken. The main priority is to reduce the number of tree snakes that are present in the habitats of the mariana crow. The second priority is to protect and conserve the habitats that Mariana crows can be found within. The 3rd and final main recovery action plan is to begin detailed research on the species so as to better monitor its numbers and condition in the future. The estimated date of recovery, assuming that all goes well and the species begins to heal according to the action plan, is in the year of 2055. 

Works Cited:

"Rota Avian Behavioral Ecology Program." The Birds. University of Washington, n.d. Web. 28 May 2015.

U.S. Fish and Wildlife Service. 2005. Draft Revised Recovery Plan for the Aga or Mariana Crow, Corvus kubaryi. Portland, Oregon. x + 147 pp.

Photo Citations in Order of Appearance:

"Rota Avian Behavioral Ecology Program." The Birds. N.p., n.d. Web. 02 June 2015.

"Mariana Crow - Pacific Islands Fish and Wildlife Office." Mariana Crow - Pacific Islands Fish and Wildlife Office. N.p., n.d. Web. 01 June 2015.

"THE REPTILES OF AUSTRALIA." BROWN TREE SNAKE Night Tiger Boiga Irregularis. N.p., n.d. Web. 02 June 2015.