Once there were billions

September 1, 2014 • 6:10 am

JAC: Yesterday I mentioned that today is an anniversary of note. I forgot that it was the 75th anniversary of the invasion of Poland by the Germans, and thus the beginning of World War II. But it’s also a biological anniversary, and Greg has volunteered to tell us about that one:

by Greg Mayer

Exactly 100 years ago today, on September 1, 1914, the passenger pigeon (Ectopistes migratorius) became extinct. We rarely know when a species becomes extinct with such precision, even in those cases, like the passenger pigeon, when the species succumbed at the hands of man. We know for the passenger pigeon, though, for by this date 100 years ago it had been many years since a passenger pigeon had been seen in the wild, and the only remaining birds were in captivity. And on this date, Martha, the last passenger pigeon, died at the Cincinnati Zoo at the age of 29.

Martha, the last passenger pigeon, by Carl Hurlbert, USNM.
Martha, the last passenger pigeon, photo by Donald Hurlbert, USNM.

Her demise marked the end of a sad chapter in the history of human exploitation of nature. In the first half of the 19th century, flocks of passenger pigeons darkened the skies of eastern North America, and could take days to pass by. Their numbers were estimated to be in the billions. A few decades of remorseless market hunting more than decimated them, and, once below a certain number, the intensely social species seemed unable to successfully reproduce. The last few pigeons in captivity stemmed mostly from the efforts of Charles O. Whitman, one of Jerry’s predecessors in biology at the University of Chicago, and an expert on pigeons. Whitman’s attempts at breeding, including sending Martha to the Cincinnati Zoo, did not succeed. Martha outlived Whitman, who died in 1910, so he did not live to see the ultimate passing of the pigeons.

The National Museum of Natural History at the Smithsonian has a temporary exhibit commemorating this sad milestone, “Once There Were Billions“, which opened in June and will be up till October of next year. I got a chance to see it just a few days after it opened. It’s a small exhibit—just two cases—but dense with specimens, objects, and information, a fine example of the style of museum exhibition that I call the “cabinet” style, which we’ve praised before here at WEIT.

Once There Were Billions, first case, at the USNM, 26 June 2014.
“Once There Were Billions”, first case, at the USNM, 26 June 2014.

After Martha’s death she was sent to the Smithsonian, where she still resides, and she is a highlight of the exhibition.

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Three specimens, including Martha herself (11). Martha and number 10 are mounted for exhibition, while 12 is prepared as a standard”study skin”. (Almost all bird specimens in a research collection are prepared in this fashion.)
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Martha signage from “Once There Were Billions”.

A number of classic illustrations are included from the Smithsonian Library, including from Mark Catesby’s Natural History of Carolina from the 1700s.

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A passenger pigeon from Mark Catesby’s Natural History of Carolina.

The exhibit also features 3 other once abundant species which were driven extinct largely by hunting: the great auk, the Carolina parakeet, and the heath hen.

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The second case in the exhibition at the USNM.

The great auk is shown in an illustration from Walter Rothschild’s Extinct Birds (which also has a passage on passenger pigeons on pp. 167-170),

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Great auk from Rothschild’s Extinct Birds.

as well as by a preserved specimen.

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Great auk at the USNM.

And the Carolina parakeet is represented by two specimens; note the passenger pigeon illustration from Alexander Wilson’s American Ornithology to the left of the parakeets.

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Carolina parakeets. Note Wilson’s passenger pigeon illustration to the lower left.

On the exhibit web page, there are links to a fine collection of illustrations and books about all four species from the Biodiversity Heritage Library.

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Signage for “Once There Were Billions”.

The Smithsonian is also showing a set of sculptures by by Todd McGrain from the Lost Bird Project; his passenger-pigeon sculpture is displayed on the USNM’s ‘front lawn’.

Passenger pigeon sculpture at USNM.

The Lost Bird Project sign at USNM.
The Lost Bird Project sign at USNM.

For further reading on passenger pigeons, I recommend A.W. Schorger’s The Passenger Pigeon: Its Natural History and Extinction (University of Wisconsin Press, Madison, 1955). Two new books have been published this year, A Feathered River Across the Sky: The Passenger Pigeon’s Flight to Extinction (Bloomsbury USA, New York) by the noted Chicago naturalist Joel Greenberg, and Mark Avery’s A Message from Martha: The Extinction of the Passenger Pigeon and its Relevance Today (Bloomsbury Natural History, London), but I have not read them.

h/t  Mark Joseph

House cats as predators

January 29, 2013 • 3:01 pm

by Greg Mayer

It’s long been known that house cats, which are introduced to most of the places they occur (the wild members of the species are found in Europe, North Africa, and western Asia), can wreak havoc on native wildlife, perhaps the most infamous case being that of the Stephens Island Wren (Xenicus lyalli). It has often been said that the wren was exterminated by the lighthouse keeper’s cat, but the story is both a bit more complex, and much more tragic: many cats were involved, not just one, and not just the Wren, but the entire Stephens Island land bird fauna was decimated.

Stephens Island Wren (from Ibis, 1895).
Stephens Island Wren (from Ibis, 1895).

A new study by Scott Loss, Tom Will and Peter Marra in Nature Communications makes new estimates of total mortality of wildlife due to house cats, and they are quite high: median estimates of 2.4 billion birds and 12.3 billion mammals annually in the United States. Money quote:

We estimate that free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually. Un-owned cats, as opposed to owned pets, cause the majority of this mortality. Our findings suggest that free-ranging cats cause substantially greater wildlife mortality than previously thought and are likely the single greatest source of anthropogenic mortality for US birds and mammals. Scientifically sound conservation and policy intervention is needed to reduce this impact.

They are particularly incensed by programs that trap feral cats, but then return them to the wild after neutering them. I must say this seems to be a crazy idea– why in the world would you put the offending predators back into the ecosystem?

The most striking thing to me was their estimate that well over 2/3 of the mortality was due to “un-owned” (i.e. feral or some slight variation thereof) cats, so that cat owners taking steps to insure that their pets do not become destructive predators, while helpful, would leave most of the problem unaddressed.

Media coverage of the study can be found at the New York Times and the BBC.

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Buller, W.L. 1895. On a new species of Xenicus form an island off the coast of New Zealand. Ibis 7:236-237.

Galbreath, R. & D. Brown. 2004. The tale of the lighthouse-keeper’s cat: Discovery and extinction of the Stephens Island wren (Traversia lyalli). Notornis 51:193-200. (pdf)

Loss, S.R., T. Will & P.P. Marra. 2013. The impact of free-ranging domestic cats on wildlife of the United States. Nature Communications (pdf)

Medway, D.G. 2004. The land bird fauna of Stephens Island, New Zealand in the early1890s, and the cause of its demise. Notornis 51:201-211. (pdf)

Extinct frog rediscovered– sort of

June 21, 2011 • 12:25 pm

by Greg Mayer

Since I first read about them when I was about 12 years old, I’ve been intrigued by the somewhat mysterious Vegas Valley leopard frogs. Known from a handful of springs, all in what is now more or less metropolitan Las Vegas, they had disappeared before the middle of the 20th century, and had been poorly known before apparently slipping out of existence. But now they’re back– sort of.

Chiricahua leopard frog from Coconino National Forest, Arizona, by Jim Rorabaugh/USFWS.

Evon Hekkala of Fordham University and her colleagues have a paper in press in Conservation Genetics in which, using DNA extracted from specimens of Vegas Valley frogs in the collection of the California Academy of Sciences, they find that Vegas frogs are closely related to the Chiricahua leopard frog of Arizona and nearby areas. In fact, the Vegas frogs are nested within the many samples of Chiricahua frogs they studied. From this they conclude that the Vegas frog is conspecific with the Chiricahua frog, and thus the Vegas Valley leopard frog is not extinct.

That the Vegas frogs (Rana fisheri) are conspecific with the Chiricahua frogs (Rana chiricahuensis) is a not unreasonable inference. North American leopard frogs, once thought to be a single widespread species, have proven to be a complex of several biological species, and although the situation is modestly clear in the eastern United States, there is much work yet to be done in the southwestern US and especially Mexico to figure out what’s going on. The Vegas frogs are not genetically identical to the Chiricahua frogs (contrary to some media reports), and, with only about 1200 base pairs examined at three loci, more differences are sure to be found.

So is the Vegas frog not extinct anymore? This isn’t just a biological species vs. amount-of-difference species concept question. One could accept, under various species concepts (and we know which one is right!), that the Vegas and Chiricahua frogs are conspecific, but still ask, is the Vegas Valley frog still extant because similar, but not identical, frogs continue to exist 100’s of kms away? I’m not sure. The US Endangered Species Act recognizes that population segments, even if they lack nomenclatural recognition or distinction, can be endangered, and be worthy of protection. And if a segment can be endangered, it can, of course, go extinct. So, while I’m glad we’ve learned who the Vegas Valley frogs’ closest relatives are, and that they’re quite similar, and that, due to the rules of nomenclature they will bear the name fisheri, I’m afraid the Vegas Valley frogs are still extinct.

The great herpetologists Albert & Anna Wright and Robert Stebbins summarized most of what will ever be known about the Vegas Valley frogs, and wrote, movingly yet scientifically, of their unsuccessful searches in the Vegas area in the 1940’s (they were last collected in January 1942, and last reported seen in the summer of ’42).  The Wrights concluded:

Our R. fisheri may go with the old springs gone, the creek a mess.

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Fisher, J., N. Simon, and J. Vincent. 1969. Wildlife in Danger. Viking, New York

Hekkala, E.R., R.A. Saumure, J.R. Jaeger, H.-W. Herrmann, M.J. Sredl, D.F. Bradford, D. Drabeck, and M.J. Blum. 2011. Resurrecting an extinct species: archival DNA, taxonomy, and conservation of the Vegas Valley leopard frog. Conservation Genetics in press. pdf

Moore, J.A. 1944. Geographic variation in Rana pipiens Schreber in eastern North America. Bulletin of the American Museum of Natural History 82:345-370. pdf

Pace, A.E. 1974. Systematic and biological studies of the leopard frogs (Rana pipiens complex) of the United States. Miscellaneous Publications, Museum of Zoology, University of Michigan 148, pp. 140. pdf

Stebbins, R.C. 1951. Amphibians of Western North America. University of California Press, Berkeley.

Wright, A.H. & A.A. Wright. 1949. Handbook of Frogs and Toads of the United Sates and Canada. Comstock, Ithaca, New York.

David Hillis of the University of Texas (who Jerry just mentioned) has done much of the work that has more recently both clarified, and pointed out the lacunae in, our understanding of leopard frogs. Many of his papers (on leopard frogs and many other subjects) are available here.

Update. David Hillis has kindly commented below, and quotes one of his papers (Hillis and Wilcox, 2005); here’s a link to the pdf of that paper.