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Yellow Crazy Ants

USFWS

Coastal Program and biologists at Marine Corp Base Hawaii teamed up to identify the effects of the invasive ant Anoplolepis gracilipes (also know as the Yellow crazy ant) on ground nesting seabirds.  

Sheldon Plentovich

  • There are no ants native to the Hawaiian Islands and although ants are known to cause harm to native invertebrates, their effect on vertebrates is less understood. Half the area used by ground-nesting seabirds on the Marine Corp Base in Kaneohe Bay was invaded by yellow crazy ants before 2010, thus providing an opportunity to carefully examine how the ants affect breeding success and chicks condition. The number of active burrows plummeted from 126 to 3 following invasion by yellow crazy ants but increased when yellow crazy ants were controlled in 2011. To assess chick condition, we measured length of bill, wing, tarsus, eye diameter, and weight. Chicks surviving in invaded areas exhibited mild to severe developmental abnormalities and had shorter bills, smaller eyes, and lighter weights than chicks outside invaded areas. It is clear that yellow crazy ants constitute a significant risk to ground-nesting seabirds and may lead to dramatic reductions in seabird numbers by reducing available nesting habitat and causing significant injuries and developmental problems in surviving chicks. Loss of nesting colonies and injuries due to yellow crazy ants are likely undetected in many areas and will occur more often as the species spreads due to human commerce and climate change.

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