American Burying Beetle larvae. Photo © Marian Brickner taken from this blog.

An Endangered Species Update

The American Burying Beetle: A Success Story?

Were they ever really endangered?

Rich Sobel
Sep 26, 2019 · 11 min read

It’s touch and go for many of our endangered species.

Lierre Keith

But maybe not for the American Burying Beetle.

Almost 2 years ago, Scientific American published an article by Hannah Nordhaus entitled “Beetle Resurrection” that made the American Burying Beetle (Necrophorus americanus) a poster child for how the oil industry and other political and economic interests regarded an endangered species that most Americans didn’t know about and previously never cared about in the first place.

As is often the case, there was a rash of articles, posts and blogs in all the top media outlets talking about the American Burying Beetle and then it was business as usual and the issue seemed to disappear.

Or was it and did it?

In this article, we’ll look briefly at the history that led to the beetle’s endangered status. To better understand our endangered friend, we’ll talk about some of the beetle’s biology. Finally, we’ll see how recovery efforts used that biological knowledge to attempt repopulation of the beetle in selected areas and we’ll see how they are faring.

(And just to alert you, dear readers, occasionally I’ll use ABB as shorthand for the full name, American Burying Beetle)

Endangered Status

Here’s a summary of the facts Nordhaus presented and a few others to bring us back up to speed.

A hundred years ago, the ABB could be found in 35 eastern states and parts of Canada. They started seriously declining some time around the 1920s.

In July of 1989 it was added to the US Fish and Wildlife Services (abbreviated henceforth as USFWS) endangered species list. At that time there were only 2 known populations; one in eastern Oklahoma and one on an island off the coast of Rhode Island.

It’s important to stress here the words “known populations”. That doesn’t mean there weren’t other populations. There might have been and probably were; they just weren’t known about at the time.

It was designated as extirpated in Canada in November 2011.

In 2015 in Oklahoma, the oil companies, fossil fuel industry groups and congressional representatives were pushing to have it downgraded (official term is delisted) on the Endangered Species Act list from “endangered” to “threatened”. To put it mildly, they found the endangered status inconvenient.

In areas where they wanted to build roads, use water resources and find more oil, the beetle’s endangered listing was causing restrictions on how the land could be used. Thus, it was an impediment to the economic growth and profits that oil production and other land uses could bring to the area.

These interests contended that the beetles were not actually endangered anymore and that if they did some habitat rehabilitation and reconstruction for them elsewhere, and ensured other appropriate habitat was preserved, that the beetle would take care of itself.

They also contended that the information that had led to the placement of the ABB on the endangered species list was no longer correct, that the beetle could be found in many locations and was not actually endangered.

That’s a pretty strong assertion!

Is their information correct?

And really, why do we care about the ABB, anyway?

A Bit of American Burying Beetle Biology

To understand the difficulties we face regarding its endangered species status and whether recovery of this creature is actually taking place or was ever even necessary, we need to know a little bit about its biology.

The beetle is quite large; actually the largest carrion beetle in North America. Adults often reach a length of 1.5 inches. They are also quite colourful; a dark shell or carapace with bright orange or red spots.

taken from National Geographic

The beetles can live in a variety of habitats; forests, wetlands, woodlands and others. The main requirement in all cases is the environment needs to be moist.

They eat all kinds of small animal carcasses. The critical factor is its weight. It must be between 4 and 10 ounces (~100 to 300 grams).

If it’s too big and heavy, they can’t move it and process it. Too small and it won’t provide enough food for themselves and their larvae.

How many new beetles can a reproductive pair produce in a year? To answer this question, we need a few more facts.

After parents mate, the female lays about 15 eggs in the tunnel adjacent to the carcass the mating pair has buried and prepared. The eggs hatch and the larvae emerge after a few days.

And now something very unusual for insects happens; the male and female feed their larvae from the buried cache by regurgitating pre-chewed mouthfuls for them to eat. Kinda like momma and poppa birds do with their newly hatched baby birds.

Not as cute, though, for sure!

New adult beetles emerge from the larvae in 45–60 days. Let’s be conservative and say on average it takes 50 days.

The new beetles are immediately ready to begin the cycle all over again.

Adult beetles live for about 1 year. Their distribution is also limited by how cold it gets in winter. They overwinter by burrowing into the soil and waiting for the warmth of spring and summer but if the winter is too cold, they die.

So if we start with one couple at the beginning of the warm “burying season”, how many beetles could we wind up with if everything goes perfectly over the year? No competition, lots of dead animals the right size, great weather, equal numbers of males and females for mating, etc.

Let’s give the beetles an 8–9 month active breeding season or about 270 days. That will be about 5 generations and that’s being generous. So let’s do the math and see how many bugs we get in 5 generations using ideal conditions and sex ratios.

The 1st generation from our original breeding pair is 15 bugs (7 new breeding pairs). These 7 breeding pairs produce 15 bugs each, or 105 new beetles (52 breeding pairs) which produces 780 beetles (390 breeding pairs). The 3rd generation is 5,850 beetles or about 2900 breeding pairs. The 4th generation is 43,875 beetles or 22,000 breeding pairs. 5th generation is about 330,000 beetles give or take a few.

Wow! That’s pretty spectacular if it was a perfect world for the beetle.

But it’s not.

So what’s the problem? Why aren’t there lots of ABBs?

No one knows for sure but here are some of the best ideas.

One important contention is that as the human population increased and its activity altered the landscape, ABB habitats became fragmented and less suitable.

There is also speculation that in their heyday, one of their primary foods was the passenger pigeon which became extinct at about the same time the beetles started to seriously decline.

Also, they are mostly active at night and outdoor lights may be disorienting them. This is probably also another reason why most people never saw them or knew about them.

They have not been found in row crops and portions of their habitat were converted to large scale agriculture.

Also, just think about it for a minute. 330,000 ABBs means 150,000 mating pairs give or take a few and that requires 150,000 carcasses. Umm, that’s a lot of dead rats and other small animals.

So to figure out how many ABBs you can reasonably expect, you need to know how many appropriate dead creatures might be found in a given sized area.

(Too bad they don’t live in sewers and subway tunnels! Lots of food there.)

But I digress.

What recovery efforts did we try?

We can raise the beetles in captivity and then release them into the wild just like we do with fish like trout and salmon.

And as a result of all the buzz a few years back, several private organizations initiated such programs. Several zoos got on this band wagon.

One of these was the Cincinnati Zoo. Let’s use them as an example.

The zoo actually has an insect care department and their staff had been preparing for a release day in June of 2019.

In collaboration with US Fish and Wildlife Service, a local nature preserve, and local volunteers which they trained, they took beetles that had been bred and “released” them.

Taken from Cincinnati Zoo blog. With the gloved hand as reference, you get a better idea of how large these critters are.

The release consisted of digging a small hole, placing a rat carcass and a breeding pair of beetles into the hole and then covering the hole with dirt.

Fairly simple.

The sites were marked so that they would be easy to find and see if they had any success.

The insect care staff returned several weeks later and found over 100 larvae produced by the beetles! Although they don’t tell us how many beetles were released, if we look at our math above, then probably about 7 mating pairs were released.

Whether or not they are truly successful in reintroducing the beetles into the area remains to be seen.

Future monitoring is necessary to see if a wild, sustainable population has developed over the course of several years.

But it is a wonderful start! And there are others so there’s cause for optimism in breeding and restoration programs.

“It’s a long-term goal, but now there’s no reason to think we can’t get them re-established all over the state of Ohio someday.” Stephen Spear, director of The Wilds in Columbus, Ohio.

The Petition to move the American Burying Beetle from Endangered to Threatened status

When a species has been officially listed as endangered by the USFWS, as the ABB was in July of 1989, it can only be removed by further legal processing. Either the agency itself conducts a review without any outside prompting or any one can submit a petition requesting review for listing or delisting.

In the ABB’s case, a formal petition was submitted on August 18, 2015 by The American Stewards of Liberty, the Independent Petroleum Association of America, the Texas Public Policy Foundation, and Dr. Steven W. Carothers.

The petition requested that:

“the beetle be delisted under the Act due to error in information such that the existence or magnitude of threats to the species, or both, do not support a conclusion that the species is at risk of extinction now or in the foreseeable future.”

Those are pretty strong words and allegations! Are they true?

Seven months later, in March, 2016 the USFWS responded and posted the following on their website:

“Based on our review of the petition and sources cited in the petition, we find that the petition presents substantial scientific or commercial information indicating that the petitioned action (delisting) may be warranted for the American burying beetle (Nicrophorus americanus), based on a lack of threats under any of the five listing factors. However, during our status review, we will thoroughly evaluate all potential threats to the species, including the extent to which any protections or other conservation efforts have reduced those threats. ”

And that’s where things stood in early 2016.

In the following 3 years the USFWS reviewers found the ABB successfully breeding in ten states: Arkansas, Kansas, Nebraska, Oklahoma, South Dakota, and Texas, on Block Island off the coast of Rhode Island, and reintroduced populations on Nantucket Island off the coast of Massachusetts and in southwest Missouri.

Thus, they are tentatively recommending delisting from endangered to threatened. As the issue is still undecided, any person has the opportunity to submit a comment here. You have until Oct 9th, 2019 to do so.

They note that the primary dangers to the ABB at the current time are increasing temperatures due to climate change and changing land usage in parts of the range.

They also note that the combined efforts of states, zoos, federal agencies, private landowners and others are what has made this delisting recommendation possible.

In addition, the USFWS is working with several zoos and associations to reintroduce the ABB in Massachusetts, Missouri and Ohio.

Did you know that there is an Association of Zoos and Aquariums comprising more than 200 members that has as one of its primary missions the protection and conservation of animals throughout the world?

I didn’t and now you do, too!

One of their programs is called the Species Survival Program and it’s the one that both the Cincinnati and Columbus zoos sought help and funding from in establishing their beetle efforts.

Always nice to give efforts like this a little plug.

And I always like to support crowd science efforts done by lay people such as members of the Audubon Society and many others.

Here’s a map from BugGuide, another citizen science site, showing where American Burying Beetles have been sighted and identified by contributors as of 2019.

BugGuide map of where Necrophous americanus has been reported. The information is based on images submitted and identified by contributors….information may be incomplete, over inclusive, or just plain wrong.

The contributors have also posted lots of pictures of the ABB and its larvae on the site.

An admission and prospects for the future

I have to say that when I started out to write this article, I thought the ABB might actually be on it’s way to extinction. But as I delved further into its story I was heartened by what I read.

As a confirmed skeptic, I was sure all the oil interests and politicians were slanting the facts to suit their economic needs. And maybe they were a little bit. But it looks like this time, they might have been right on the money (pun intended).

Maybe in our ignorance, it was mistakenly listed as endangered in the first place. We’ll never know the answer to that for sure.

So I’ll go on record here and say I still think we should do everything we can to help this insect thrive and earn the delisting action. I believe that restoration to its former range IS possible with the right effort.

And just because it’s been found in more places than before is no reason to slack off on the restoration efforts. It’s sustainability is not proven yet.

Like I asked at the beginning of this article, how many of us even knew there was an American Burying Beetle and even cared one way or the other about it?

Maybe now you do?

Now, to digress, dear reader, into a bit of fun biology.

Well, there is one thing I care about for sure and that’s its name. See my post about naming things. The American Burying Beetle aka Giant Carrion Beetle genus and species names are Necrophorus americanus.

The genus name is derived from the Greek nekrophoros which meansburying the dead”. Which comes from the roots nekr- necr- + -phoros bearing, burying (from pherein to bear, carry to burial). americanus- well you know that’s where it comes from!

And that’s what it actually does. It carries the dead animals to the holes it digs for them!

I couldn’t resist that bit of taxonomic trivia. And I think it’s fun to know where a creature’s scientific name comes from.

Also, I didn’t go very deeply into the ABB’s biology in this post.

One interesting thing is how it preserves the carcass and keeps other carrion feeders away from it by coating it with a repellent substance.

The substance they use to do this might be a possible source of antibiotic compounds we don’t know about. More research about this fascinating carrion feeder is needed, that’s for sure!

Until next time,

Rich

Hey! Are you interested in biology news and fascinating/ cool stories — for yourself or to share with your friends or kids? Then grab my “3 Fascinating Creatures” ebook here and sign up to get my weekly newsletter.

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Rich Sobel

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Rich uses plain language to explore in-depth biology topics | fascinating plants and exotic creatures | www.biology4everyone.com | indulge your curiosity!

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Rich Sobel

Written by

Rich uses plain language to explore in-depth biology topics | fascinating plants and exotic creatures | www.biology4everyone.com | indulge your curiosity!

The Startup

Get smarter at building your thing. Follow to join The Startup’s +8 million monthly readers & +794K followers.

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