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American Burying Beetle in South Dakota

american buryig beetle

What is a burying beetle?

Burying beetles are just one small group of beetles among the over 350,000 species of beetles known to science. Burying beetles are in the genus Nicrophorus and are among the most fascinating insects in the world. Nicrophorus beetles feed on dead animals (carrion). They also use carrion as a food source for their young. They are unique among the beetles in that they provide parental care to their young.

Nicrophorus beetles are strong fliers. During the breeding season, Nicrophorus beetles fly over large areas searching for carrion of the proper size for rearing a brood. When a carrion source is located, a male and female cooperate to bury the carcass, clean and prepare it with preservative secretions. Discovery and preparation of the carcass causes rapid hormonal changes in the female that trigger egg maturation. The female lays eggs in the soil in the brood chamber soon after the carcass is prepared. One or both adults will remain in the brood chamber to protect the carcass and the brood from competitors and predators.

Nicrophorus beetles have a symbiotic relationship with phoretic mites. The mites live on the beetles. Once the beetles enter the brood chamber, the mites eat fly eggs, preventing loss of the food supply to fly maggots. The mites also serve to keep the beetles clean when feeding on carrion. In return the mites benefit by being transported to sources of food.

In South Dakota, twelve different species of Nicrophorus beetles have been documented. Some species are very common, others are rare, and one species, the American burying beetle, is federally listed as endangered.

The American Burying Beetle

The American burying beetle, Nicrophorus americanus, is the largest Nicrophorus species in North America, with adults reaching lengths of 25-45mm. The species is easily recognized by its large size and orange-red pronotum and frons.

Historically, this once abundant species occurred in thirty-five states, the District of Columbia, and three Canadian provinces of eastern and central North America. The species has disappeared from over ninety percent of its former range, and until recently populations were known to exist only from Block Island off the coast of Rhode Island and eastern Oklahoma. On August 14, 1989, the American burying beetle (ABB) was placed on the federal list of endangered and threatened wildlife and plant species. Since federal listing, relatively large numbers of ABB have been reported from localized areas in western Arkansas and central Nebraska. It has also been documented in Kansas.

In South Dakota, records of seven ABB specimens deposited at South Dakota State University insect collection indicate that the species may have ranged from Brookings and Union counties in the east to Haakon county in the west. The last known collection dates were in 1945. Numerous surveys, specifically for ABB, have been conducted in various parts of the state since 1990. These collecting efforts did not detect ABB in the historic range in South Dakota. Map 1 shows the approximate locations of the areas surveyed.

The collection of a single specimen of ABB,near Jamison, Nebraska, just south of the South Dakota/Nebraska state line in August 1994 prompted South Dakota Department of Game, Fish and Parks to initiate extensive surveys of southern Gregory, Tripp, and Todd counties in 1995. A large population of the endangered beetle was discovered, ranging from southwest Gregory County through southern Tripp County. Map 2 shows the current distribution of the American burying beetle in those counties.

These links are excellent sources of additional information on the American burying beetle:

Center fro American Burying Beetle Convervation
Endangered American Burying Beetle Update
American Burying Beetle (ABB) Texas
US Fish & Wildlife Service - SD Field Office -American Burying Beetle

The Recovery Plan

The U. S. Fish and Wildlife Service published the American Burying Beetle Recovery Plan in 1991 {U.S. Fish and Wildlife Service. 1991. American burying beetle (Nicrophorus americanus) recovery plan. Newton Corner, MA. 80 pp.}. The recovery plan lists recovery objectives that must be met before the species can be downlisted or delisted. The recovery plan is in the process of being rewritten to reflect more current information on the status of the species.

Under the current recovery plan, reclassification will be considered when:

a. Three populations of N. americanus have reestablished (or additional populations discovered) within each of four broad geographical areas of its historical range: New England, the southeastern states, the midwestern states, and the Great Lakes states.

b. Each population contains a minimum of 500 adults as estimated by capture rates per trap night and blacklight effort.

c. Each population is demonstrably self-sustaining for at least five consecutive years

d. Ideally, each primary population contains several satellite populations to which beetles disperse and from which new habitats are colonized.

Since the recovery plan was written, genetic research has shown that there is little genetic variation between populations on the east coast, Oklahoma, Arkansas, Nebraska or South Dakota {Szalanski, Allen L., S. S. Sikes, R. Bischof, and M. Fritz. 2000. Population Genetics and Phylogenetics of the Endangered American Burying Beetle, Nicrophorus americanus (Coleoptera: Silphidae). Annals of The Entomological Society of America 93 (3): 589-594}. The requirement for populations in four geographical areas may no longer be necessary since there is no genetic divergence among existing populations.

Since 1991, large populations of ABB have been discovered in Arkansas, Oklahoma, Nebraska, and South Dakota. A population estimate of over 3000 individuals was made for one large population along the North Platte River in Nebraska (Peyton, M.M. Range and Population Size of the American Burying Beetle (Coleoptera:Silphidae) in the Dissected Hills of South-central Nebraska. Great Plains Research 13(1): 127-138). The sandhills country of Nebraska also supports a large population that is scattered throughout the sandhills wherever the water table is close enough to the surface to support trees. The South Dakota population is probably an extension of the large sandhills population.

Population Estimate for South Dakota

The South Dakota Department of Game, Fish and Parks is conducting a population estimate of the South Dakota population. A sampling area of approximately 100 square miles was intensively sampled for 9 days from June 17-25, 2005. American burying beetles were marked with numbered tags and released. Over the sampling period, 168 ABB were marked and released. Thirty-seven were recaptured once and eight were recaptured twice. Table 1 lists the recapture results for the June sampling period.

In the August 10-19 sampling period, 323 ABB were captured, marked and released in the same study area. Sixty-six ABB were recaptured once, ten were recaptured twice, and one ABB recaptured 3 times.Table 2 lists the results for the August sampling period.

Based on past sampling efforts (Map 2) there is approximately 500 square miles of core habitat and 800 square miles of potential habitat where ABB have been captured. One hundred sixty-eight individual ABB were taken within 100 square miles in June, all of these were adult beetles. Three hundred twenty-three ABB were marked in August, 96% of these were freshly emerged teneral beetles. Based only on raw data from the sampling a minimum population of over 500 ABB has been demonstrated. The final population estimate, using standard mark and recapture population estimate equations, will be higher than the estimate from raw data.

The South Dakota population has been self-sustaining since its discovery in 1995. South Dakota Dept. of Game, Fish and Parks has been monitoring the population annually. The South Dakota population meets the requirements of the recovery plan for a sustainable population. This information will be provided to the U.S. Fish and Wildlife Service when the study is completed.

Update: Population estimate research has been published

Citation: Backlund, D. C., G. M. Marrone, C. K. Williams, and K. Tillman. 2008. Population Estimate of the Endangered American Burying Beetle, Nicrophorus americanus, Olivier (Coleoptera: Silphidae) in South Dakota. The Coleopterists Bulletin 62(1): 9-15.

Abstract: Annual monitoring surveys for the endangered American burying beetle, Nicrophorus americanus Olivier, have been conducted in south central South Dakota since 1995. The population has been stable in abundance and distribution. Two mark and recapture surveys were conducted in June and August, 2005 in southern Tripp County, South Dakota, USA. Using baited pitfall traps, we captured and marked 168 specimens of N. americanus during 410 trap-nights in June. In August, 323 specimens were captured and marked in 450 trap-nights. We estimated the population size of N. americanus in an area of approximately 220 km2. Estimates were obtained using a family of models (program CAPTURE) that incorporate several sources of variability in probability of capture. The June population estimate ( 1 SE) was 442 73 and a 95% confidence interval of 333-624 adults. The August population estimate ( 1 SE) was 901 117 with a 95% confidence interval of 714-1,177 tenerals and adults combined.

How do we catch American burying beetles?

Burying beetles are rarely seen by people unless they check dead animals for their presence. The most efficient method of catching and detecting different species of burying beetles is to use pitfall traps baited with aged meat. Burying beetles can detect the odor of dead animals up to two miles and will fly in to investigate. They will land on the ground near the source of the odor then walk to the source. If a pitfall trap is baited with aged meat, the burying beetles will fall in and be unable to escape. By using pitfall traps, biologists can capture large numbers of burying beetles. Some species are nocturnal while others are diurnal. To catch the nocturnal species, like the American burying beetle, pitfall traps are baited overnight. The following morning biologists can check the traps and document the species captured.

A pitfall trap is simply a container that is buried with the top even with the surface of the ground. The bait is prepared a few days ahead of time by placing chunks of meat in baby food jars, then holes are punched in the lid to allow the odors to escape. The bait is aged for 4-5 days. A wooden cover on two-inch legs is staked over the trap to keep rain and sunlight out.

Gary baits trap

trap

Pitfall trap ready to be buried

 

Gary Marrone baiting a trap

beetle trap

Pitfall trap in the ground in American burying beetlehabitat

 

beetles ready to mark

 

 

 

 

 

 

Four American burying beetles ready to be marked

tagging beetle

Micah Reuber
tagging an American burying beetle




Tagged American burying beetle ready to be released

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