Friday, July 6, 2012

A Block Island Endangered Species

Since I just returned from a fun-filled vacation to MA and Block Island, RI, this week’s endangered species is the American Burying Beetle (Nicrophorus americanus) (photo from the SD Field Office of the FWS).  This nocturnal, orange and black beetle is the largest of the 32 species of burying beetles found in North America, usually 1 to 1.5 inches.  Talk about a unique lifestyle!  Here’s how the Center for Biological Diversity describes how the beetles mate and protect their young (activities that occur from April to September, but mostly in June and July, according to the NY Department of Environmental Conservation):  The American burying beetle is “uniquely dependant upon quail-size carrion weighing 100-200 grams [1, 15]. Males smell freshly dead mammals and birds (and occasionally even fish) within an hour of death and up to two miles away. Females arrive shortly thereafter, attracted by male pheromones. A competition ensues and is typically won by the largest male and female. Lying on their backs, the winning couple inches into an excavated burial chamber. During this time, orange phoretic mites borne by the beetles leap to the carcass, cleaning it of fly eggs and microbes. The buried carcass is relieved of its feathers, feet, tail, ears and/or fur. Now known as a "brood ball," it is coated with oral and anal embalming secretions to retard fungal and bacterial growth. The beetles then mate and within 24 hours lay eggs in the soil near the carcass. White grubs emerge three or four days later and are carried to the carcass. The parents also defend the grubs from predators and feed them regurgitated food. The American burying beetle is one of the few non-colonial insects in the world to practice dual parenting. In approximately a week, the grubs leave the chamber and pupate into adults.”  So cool!

The American burying beetle used to be found from Nova Scotia, through the midwest, and down to Florida and Texas.   Unfortunately, the population has declined by 90% from its historical distribution.  Scientists hypothesize that species decline is due to habitat loss and fragmentation, leading to a decline of the beetle’s carrion source. 

So what does this have to do with Block Island, RI?  Well it turns out that Block Island is the home to the only population of American burying beetles east of the Mississippi river.  These beetles can be found at Block Island National Wildlife Refuge, along with other endangered species, such as the piping plover, and the largest gull colony in Rhode Island.  We didn’t see any of the beetles while we visited the island, but maybe we’ll see them next time!


[1] U.S. Fish and Wildlife Service. 1991. American burying beetle (Nicrophorus americanus) recovery plan. Newton Corner, MA.

[15] Stevens, J. 2005. Conservation of the American burying beetle. CommuniQue, September, 2005:9-10.

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