Killer mice: rodents threaten the largest colony of albatrosses

Killer mice: rodents threaten the largest colony of albatrosses

Population of Laysan albatrosses in Midway Atoll is rapidly declining due to mice.

The Midway Atoll National Wildlife Refuge and Battle of Midway National Memorial is the home for more than 3 million seabirds of 30 various species. Most notably, this is the place where world’s largest population of Laysan albatrosses nest.

Employees of the U.S. Fish and Wildlife Service working in the Pacific region have spent three years to find out who was attacking the birds nesting on the atoll for decades. Since 2015 they started noticing terrible open wounds on the heads, backs, and wings of the albatrosses. More than a thousand birds have died from these injuries, while many birds were forced to leave this dangerous atoll.

At first, experts assumed that albatrosses were attacked by hawks or owls. The situation was resolved as soon as 24-hour video surveillance of nesting areas was established. It turned out that ordinary mice declared war to “neighbors”. The footage showed rodents climbing on the backs of sleeping birds and biting them.

Landscape view of colony

Employees of the U.S. Fish and Wildlife Service are now puzzling over the reasons of such an aggressive behavior. The fact is that mice and black rats are living in Midway Atoll for 75 years already. Previously, researchers recorded only isolated cases of attacks on albatrosses on the part of omnivorous rodents. However, following the 2015 hatching season, mice look like becoming mad and their attacks became regular and massive.

It shall be noted that this situation is posing a serious threat to the population as a whole. A total of 73% of all the Laysan albatrosses are nesting in Midway Atoll. Researchers believe that every bird is priceless, since it plays an important role in preservation of entire colony of birds. After all, one pair of albatrosses have one egg every two years. Another factor is that birds are vulnerable to external threats, since they devote almost all of their time to raise their offsprings. For these very reasons, safe nesting place is the prerequisite for survival of species. What is more, mice breed very quickly and in large numbers, and it is obvious that they will win this battle if no timely actions are taken.

As of today, the U.S. Fish and Wildlife Service have received more than 500 proposed projects on how to resolve this problem.

 

Photo: Duncan Wright


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