American Burying Beetle

American Burying Beetle

Roger Williams Park Zoo (RWPZ) is the national headquarters for the Association of Zoos & Aquariums’(AZA) American Burying Beetle (ABB) Species Survival Plan (SSP). RWPZ Director of Conservation Programs, Lou Perrotti, leads the national SSP.

In the early 1990s, the United States Fish and Wildlife Service (USFWS) initiated a project to capture ABB mating pairs from Block Island and attempt to rear them in captivity, with the aim of repopulating them in a former habitat. Husbandry and breeding techniques for captive ABB were developed at Boston University by Adrea Kozol during the first years of the project.

RWPZ joined the project in 1994 and in 1995 became the sole breeding facility for the American burying beetle recovery program. Since then we have continuously contributed a breeding facility and expert keeper staff, husbandry and breeding data, and field support to the project. We have reared over 5000 ABB’s at our facility and released over 2800 in Nantucket, MA. The ABB population has stabilized, and is growing so it appears that our reintroduction efforts have successfully established an ABB population on Nantucket Island.

In 2006, the Association of Zoos & Aquariums created a Species Survival Plan for the ABB, the first for a terrestrial invertebrate. Lou Perrotti, Director of Conservation Programs, was selected to direct this program which has expanded to 2 other participating Zoos.

Questions? Contact Louis Perrotti, Director of Conservation Programs at Lperrotti@rwpzoo.org or call (401) 785-3510 ext. 335.

Details & Results to Date
Why is this beetle endangered?

There are 15 species of burying beetles in North America, but only the ABB (Nicrophorus americanus), has experienced a drastic decline in population.
In the 19th century, ABB populations covered the entire eastern half of the United States and neighboring Canadian provinces. By the 20th century, spotty populations remained only in Arkansas, Oklahoma, Kansas, Nebraska, extreme southern South Dakota, and north eastern Texas, and in the east only on Block Island off the southern coast of Rhode Island. In 1989 the United States Fish & Wildlife Service declared the ABB endangered.

Human beings are most likely the major cause for the near extinction of the ABB. Hunting and development destroyed and fragmented wildlife habitat, eliminating the top tier of animal predators such as wolves, bears and wild cats.  Scavenger predators like foxes, raccoons, and skunks then multiplied in greater numbers, now competing for and affecting the availability of food for carrion eaters. Passenger pigeons were plentiful in the 19th century, but their numbers declined significantly at about the same time as the American burying beetle. Scientists think that the ABB, because of its relatively large size and the need for carrion weighing between 80 and 180 grams on which to rear its young, depended on the carrion of these larger birds while other carrion beetles can utilize carcasses of smaller birds and mammals.

Our use of night time lighting, bug zappers and pesticides also may have a significant impact on the ABB.
 

Why does it matter?

When a species is lost, the fragile balance of a habitat is disrupted, sometimes permanently. The American Burying Beetle, like all species, has its own important role in the ecosystem. All carrion beetle species require a vertebrate carcass to rear their brood. Known as nature's most efficient and fascinating recyclers, these burying beetles are important scavengers that recycle decaying animals back into the ecosystem.  They return nutrients to the earth which in turn stimulates the growth of foliage. By removing carcasses from the ecosystem, the ABB also helps keep fly and ant numbers from reaching epidemic proportions. 

This beetle and other invertebrate species act as “indicator species,” alerting scientists about the health of the environment. If this insect cannot survive it is a sign that the habitat has changed in an unhealthy way. Over time, this can have a ripple effect. According to the USFWS, over 500 species of animals have become extinct, suggesting North American habitats are becoming significantly diminished. We are wise to pay attention.
 

The Cooperative Conservation Project: Results to date

Maintaining an ABB population on Nantucket may require augmentation of natural carrion resources. Providing several hundred quail carcasses at the appropriate time could maintain a population of several hundred beetles. Monitoring the population could be reduced in scope to trapping in late June with the large grid for four to five days to capture a snap shot of the reproductive population. Beetles captured in this time could be provisioned in a central area. Late summer trapping around that provisioning area would be a very efficient way of marking an overwintering cohort.

2014 Field Season Summary

  • Results from the summer of 2014 further support the premise that ABB’s on Nantucket are dependent on human intervention in the form of provisioning to maintain a healthy population. The lack of ABB captures during the first late summer trapping interval was especially telling. The nightly temperature was within the range for ABB’s to be active and we were trapping across their known range on Nantucket, yet did not catch a single beetle.  No captures strongly suggests there was no successful reproduction on natural carrion sources.
  • This year’s results are relatively similar to previous years’ except for colder nightly temperatures. The cooler temperatures may be the cause for delayed maturation in the broods. We excavated broods expecting to find 3rd instar larvae but consistently only found 1st and 2nd instars. This delay may also explain why we caught so few teneral beetles in the second trap interval, which was timed to coincide with the teneral emergence had it been on schedule. Beetle size was larger than in 2013 and more comparable with pre 2013 sizes. The over winter survival rate was similar to previous years as was the distance moved between 2013 and 2014 (about 2Km). 

2015 Field Season Summary

  • We captured more beetles than expected in 2015, and had the highest provisioning success rate recorded for this project in more than ten years. Based on a decreasing population trend since 2011, we expected to catch about half the number of beetles seen in 2014. However, it appears that our provisioning effort is now maintaining a small population. As in 2014, we did not catch any teneral beetles produced by natural pairing and reproduction so we assume a majority of beetles currently in the population are direct descendents from provisioned broods.
  • This project has now collected five years of data on how a reduced provisioning regime affected the established ABB population on Nantucket. It is clear that the monitoring and provisioning effort is responsible for maintaining this population. Key points that we have learned:
    • Trapping over the entire local range of the ABBs through the reproductive season is effective in catching most of the adults. This is partly due to the fact that ABBs disperse several kilometers between their emergence as tenerals in the late summer and their reproductive season in the early summer the following year.
    • Selecting a successful site for traps is difficult. When possible, sites with very low capture rates should be moved to nearby areas in case vegetation or topography are inhibiting trap effectiveness.
    • Careful provisioning can greatly increase provisioning success. Sites selection should avoid dry sandy soils and provisioning should occur early enough in the season to avoid the dry conditions of midsummer.

2016

  • Continue trapping using the grid arrangement.
  • Consider tethering carrion in transects to determine effectiveness of just providing quail to maintain the population. Seeding the ABB range on Nantucket with vertebrate carcasses could be an efficient way of increasing the reproductive resource.

Long term recommendations

  • Use 2017 and 2018 to increase the population and gather data on how effectively ABBs recruit to supplied carrion left on the ground surface.
  • Based on conclusions from careful and early provisioning, begin a program of supplying carrion by distributing it within the ABB range on Nantucket.
  • Begin shortened early summer monitoring and provisioning. Aim for provisioning 25 broods. In the late summer trap near the broods to efficiently mark an overwintering cohort.
  • Focus research on carrion availability, dispersal, overwinter survival, and predation.
     
Species Survival Plan for the American burying beetle

In 2006, the AZA established a Species Survival Plan (SSP) for the American burying beetle, the first terrestrial invertebrate to be included in the program. RWP Zoo Director of Conservation Programs Lou Perrotti was named as the national SSP coordinator for the species.

The ABB SSP focuses on these goals

  • Standardize and replicate the husbandry and field techniques used across the species’ range.
  • Initiate and conduct research initiatives looking into the natural history, biology, and physiology of N. americanus.
  • Continue to maintain genetically diverse captive populations and create and maintain a studbook.
  • Continue to supply captive reared ABB individuals for U.S. Fish & Wildlife Service approved reintroduction and research efforts.
  • Initiate and conduct surveys to monitor existing populations and look for additional populations.
  • Develop and distribute a strong universal conservation education component.
     
Honors for RWP Zoo’s ABB Project

2006

  • AZA Top Ten Conservation Success Stories
  • AZA Edward H. Bean Award
  • Selection as leader of the ABB Species Survival Plan

2000

  • AZA North American Conservation Award