American burying beetle

Historically, the American burying beetle ranged from the southern fringes of Ontario, Quebec, and Nova Scotia through 35 eastern and central U.S. states, including New Jersey. Based on dated collections specimens, the beetles became quite rare east of the Appalachians between the late 1800s and the 1920s, with the last known historic locations documented in the early 1940s.

In New Jersey, the most recent record was a specimen collected in the Hightstown, Mercer County, in 1919. Between 1896 and 1910, beetles were also recorded in Camden, Glouster, Ocean, and Sussex Counties, with two undated records attributed to Essex County (Raithel 1991).

Today, the beetle is found in only seven states and is absent from more than 90% of its historic range. East of the Mississippi River, the only known naturally occurring population exists on Block Island, Rhode Island. Reintroduced populations of captively breed beetles are present on Penikese and Nantucket Islands in Massachusetts. Other populations, mostly small ones, exist to the west of the Mississippi River in Oklahoma, Arkansas, Kansas, Nebraska, and South Dakota.

Whether it is coastal grassland/scrub in the East or prairie or savannah-like oak-hickory forests with open understories in the Midwest, American burying beetles require landscapes that are open enough to allow a large beetle with limited flight maneuverability to be active at night.

American burying beetles consume a wide range of food, from vertebrate carrion of varying size to insects. The antennae of American burying beetles have receptors capable of detecting chemicals emitted by dead vertebrates. From as much as two miles away, they can locate a dead mouse within an hour of its death (Ratcliffe 2001). When not brood rearing, adults may also feed on live insects.

Adults are active between late April and September, most breeding activity occurs in June and July. Airborne only at night, usually only when nighttime temperatures exceed 60oF, the adults fly about seeking odors of recently deceased vertebrates (Raithel 1991). If the carcass of the right size, about the size of a mourning dove or young cottontail rabbit, a male and female pair up (Amaral and Prospero 1999). The pair buries the carcass, usually before dawn. They clean the carcass of feathers and fur and cover it with secretions to preserve it. Then the female lays 10 to 30 eggs in a brood chamber next to the carcass. The carcass will provide food for the larvae (Ratcliffe 2001). The larger the carcass, the more larva that survive.

The American buying beetle is remarkable and is known to exhibit parental care over its young. Female beetles stay with the young until the carcass is completely consumed and larval development is completed. Males guard the larva and carcass from other beetles and intruders (Raithel 1991). Larvae crawl into the soil to pupate. After 48 to 60 days from carcass burial they emerge as adults. The beetles overwinter as adults to breed the following year, their parents can breed again during the warm summer months; however, both will die soon.

The prevailing theory indicates habitat fragmentation was largely responsible for the American burying beetle’s decline (Raithel 1991). Such fragmentation reduced or eliminated prey species favored for breeding carrion, such as passenger pigeons, wild turkeys and prairie chickens. Meanwhile, the resulting increase in “edge” habitat increased the number of scavengers competing with the beetles for the carrion, such as the American crow, raccoon, fox, opossum and skunk (Amaral, pers. comm.).

The American burying beetle was listed as federally endangered in 1989. Even though it apparently has been extirpated from New Jersey, as a result of the federal listing the state listed the beetle as threatened in the same year.

At the time of the federal listing, the beetle was known to occur naturally on only Block Island, R.I. and in one Oklahoma County. Subsequently, the U.S. Fish and Wildlife Service required surveys during environmental planning for proposed developments in eastern Oklahoma and western Arkansas. As a result of these surveys, several additional populations were found. In the East, attempts have been made to expand the population by breeding adults captured on Block Island and reintroducing their offspring on two Massachusetts islands, Penikese and Nantucket. Building on the early experience of Boston University, zookeepers at the Roger Williams Park Zoo in Providence, R.I., have since raised more than 25 generations of American burying beetles. Like Block Island, both Penikese and Nantucket islands are free of predators, which would compete with the beetles for carcasses. As of 2001, it was still unclear, however, whether the reintroduced populations had become self-sustaining. Eight years after the end of a four-year reintroduction program on 70-acre Penikese Island, beetles could still be found.