American Burying Beetle Recovery Program

Most people tend to think about conserving big fluffy animals, but preserving the web of life requires so much more. In the words of Aldo Leopold, renowned scientist and environmentalist, it’s about “Saving all the pieces.”

One of the pieces Roger Williams Park Zoo is trying to save is the American burying beetle (Nicrophorus americanus), an endangered two-inch-long black insect with red-orange markers. Known as nature’s most efficient and fascinating recyclers, burying beetles are important scavengers responsible for recycling decaying animals back into the ecosystem.

Once residing in 35 states, the American burying beetle has drastically declined in numbers and range. In fact, Block Island, Rhode Island, is the home of the last known naturally occurring population of the ABB east of the Mississippi River. These beetles are now found to naturally occur only in Rhode Island, Arkansas, Oklahoma, Nebraska, Kansas, South Dakota, and Texas.

In the early 1990s, the U.S. Fish & Wildlife Service (USFWS) and Roger Williams Park Zoo established a breeding program for the American burying beetle (ABB). The initial project was 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 the captive ABB were developed at Boston University by Adrea Kozol during the first years of the project.

In 1994, RWPZ became the sole breeding facility for the American burying beetle recovery program. Since 1995, RWPZ has successfully reared over 5,000 ABBs over multiple generations, starting with 19 male and 11 female beetles taken from Block Island. To date, the program has released over 3,000 beetles to their historic habitat in Nantucket, MA. The RWPZ continues to monitor the reintroduced population, and supplements it annually with captive-raised beetles.

In 2006, the Association of Zoos & Aquariums (AZA) created a Species Survival Plan for the American burying beetle, the first for a terrestrial invertebrate. Lou Perrotti, Director of the Zoo’s Conservation Programs, was selected to direct this program, which has now expanded to 3 other participating zoos.

Why is the American Burying Beetle Endangered?

There are 15 species of burying beetles in North America, but only the American burying beetle (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, northeastern 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. As a result, scavenger predators such as foxes, raccoons, and skunks multiplied in greater numbers, leaving them to compete for food sources that the ABB and other carrion eaters also needed, thus greatly decreasing the availability of this food source. Passenger pigeons were plentiful in the 19th century, but their numbers declined significantly at about the same time as the American burying beetle declined in numbers. 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. The common use of nighttime lighting, bug zappers, and pesticides also may have a significant impact on ABB populations.

American Burying Beetle: 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 – A Closer Look

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 ABBs 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 ABBs to be active and we were trapping across their known range on Nantucket, yet did not catch a single beetle. This strongly suggests there was no successful reproduction on natural carrion sources.

The 2014 results are relatively similar to that of 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 descendants from provisioned broods.

As of 2015, the project 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. The following are some key points we discovered:

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 success. Site selections should avoid dry sandy soils and provisioning should occur early enough in the season to avoid the dry conditions of midsummer.

2016 Field Season Summary

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.

2021 Field Season Summary

For the first time in nearly 56 years, American burying beetles are back in New York State. In early September, 2021, Lou Perrotti, the Zoo’s Director of Conservation Programs, met with Dr. Brandon Quinby, Research Scientist & Conservation Biologist at SUNY Cobleskill, to deliver 40 beetles. These would act as the founder population in New York. The reintroduction efforts wouldn’t be possible without our amazing partners, including SUNY Cobleskill’s Environmental Management program.

Long Term Recommendations & Goals

Increase the population and gather data on how effectively ABBs recruit to the supplied carrion.
Introduce captive-reared beetles.
Based on conclusions from careful and early provisioning, begin a program to supply carrion by distributing it within all the ABB range on Nantucket.
Continue to conduct early summer monitoring and provisioning. Aim to provision all captured beetles and all of those re-introduced annually.
In late summer, conduct a monitoring session to trap the young that the provision broods produced. This will mark as many beetles as possible to efficiently assess an overwintering cohort.
Focus research on carrion availability, dispersal, overwinter survival, and predation.

The ABB SSP Focus & Goals

Standardize and replicate the husbandry and field techniques used across the species’ range.
Initiate and conduct research initiatives regarding natural history, biology, and physiology of americanus.
Continue to maintain genetically diverse captive populations.
Create and maintain an ABB studbook.
Continue to supply captive-reared ABB individuals for reintroduction and research efforts approved by U.S. Fish & Wildlife Service.
Initiate and conduct surveys to monitor existing populations, and look for additional populations.
Develop and distribute a strong universal conservation education component.

Roger Williams Park Zoo’s ABB Project Honors

2021

Louis Perrotti awarded the Endangered Species Recovery Champion Award, the U.S. Fish & Wildlife’s highest honor

2020

AZA North American Conservation Award

2006

AZA Top Ten Conservation Success Stories

AZA Edward H. Bean Award

Selection as leader of the ABB SSP

2009

Jane Goodall includes a chapter on the ABB in her book, Hope for Animals and Their World

2010