Assessing the extinction risk of the great bustard Otis tarda in Africa

Palacín, C., Martín, B., Onrubia, A. & Alonso, J. C. 2016. Assessing the extinction risk of the great bustard Otis tarda in Africa. Endang Species Res 30: 73–82. doi: 10.3354/esr00726 (Open Access)

Abstract:

We studied the dynamics and trend of the last extant population of great bustards Otis tarda in Africa. Moroccan great bustards are the southernmost population of this species, and thus show the characteristics of a peripheral population: small size, isolation and low gene flow. Available counts indicate a severe population decline (62% in the last 15 yr), as well as a contraction of the species’ distribution. We used a population viability analysis (PVA) to evaluate the quasi-extinction risk and to identify the most important threats. The estimated geometric growth rate of the more realistic of a set of possible scenarios was 0.87 (95% CI: 0.85, 0.89). This implies a 13% annual decline over 50 yr. However, projections derived from these results should be interpreted with caution, because models have a great deal of uncertainty and vital rates from Iberian populations may be different from those of the Moroccan population. PVA showed the negative consequence of human-induced mortality. According to the model that best fits our census data and if present threats remain in the coming years, this peripheral population could go extinct in ca. 20 yr. Agricultural intensification, infrastructure developments and new power lines in rural areas where the species occurs are causing habitat destruction and fragmentation and increasing artificial mortality. Urgent conservation measures, especially to reduce human-induced mortality, are needed to save African great bustards from extinction. We suggest that these findings can be generalized to other peripheral great bustard populations living in highly humanized landscapes.

Great Bustard (Otis tarda): a vulnerable species
Great Bustard (Otis tarda): a vulnerable species (Andrej Chudý, via Wikipedia Commons)

100 years after ‘Martha’, The Last Passenger Pigeon: reflexions

Never to Be Repeated: Lessons From the Passenger Pigeon, published in the Cornell Lab of Ornithology website about the centennial of the death of Martha, the very last Passenger Pigeon (Ectopistes migratorius):

“A hundred years after they went extinct, Passenger Pigeons are suddenly everywhere you look on the Internet. Scientists and historians, newspapers and blogs alike are revisiting what is likely the starkest conservation lesson we’ve ever learned. That’s because Monday, September 1, 2014, marks the centennial of the death of Martha, the very last member of what was once the most abundant bird on the planet.

In an op-ed for the New York Times today, Cornell Lab director John Fitzpatrick remembers the extinction of the Passenger Pigeon and then looks ahead, wondering, “What can we tell Martha we’ve learned since her passing?”

We learned the main lesson quickly, Fitzpatrick argues: that extinction is forever, unless we do something about it”.

Continue reading at the Cornell Lab of Ornithology website.

Martha, The Last Passenger Pigeon. Image from Smithsonian Institution Archives

Martha, The Last Passenger Pigeon. Image from Smithsonian Institution Archives.

Read also at the Smithsonian Institution website:

“Martha” a passenger pigeon named after George Washington’s wife, was the last of her kind. Immediately following her death in 1914 at the Cincinnati Zoological Gardens, she was packed in an enormous 300-pound block of ice and shipped to the Smithsonian.

The passenger pigeon, Ectopistes migratorius, was once the most common bird in the United States, numbering in the billions. Passenger pigeons lived in enormous colonies, with sometimes up to 100 nests in a single tree. Migrating flocks stretched a mile wide, turning the skies black. Bird painter John James Audubon, who watched them pass on his way to Louisville in 1813, described “the continued buzz of wings,” and said “the air was literally filled with pigeons; the light of noon-day was obscured as by an eclipse…” When he reached his destination, 55 miles away, the birds were still passing overhead, and “continued to do so for three days in succession.” The passenger pigeon, a wild bird, is not to be confused with the carrier pigeon, a domesticated bird trained to carry messages.

With such abundance, it seemed unimaginable that the passenger pigeon could ever become extinct. But due to overhunting, habitat loss, and possibly infectious diseases that spread through the colonies, they became increasingly rare by the late nineteenth century. The last confirmed sighting of a wild passenger pigeon was in 1900. After that, only a few survived in captivity. “Martha,” who lived her whole 29-year life in the Cincinnati Zoo, was the last.

The photograph from the Smithsonian Institution Archives.

More reading:

Post-pigeon: 100 years since most common bird’s extinction in The Guardian. Mark Avery on the lessons we need to learn from the loss of the passenger pigeon – billions once flew across the US.