Saturday, October 22, 2016

The Extinction of a Tool User

There are many reasons to prevent the extinction of species, and one of them is that we have a lot still to learn about plants and animals. My last blog covered three species that have been brought back from the brink of extinction thanks to concerted human effort. Cross your fingers with me that the same can be done for this fascinating one.

U.S. Fish & Wildlife Service
The Hawaiian crow (Corvus hawaiiensis) - known in Hawaiian as the ʻalalā - is a tool user. It can clutch a stick in its bill and use it to dig food out of a crevice. That already puts it in a unique group of bird species that have been found to use tools in this way. But the Hawaiian crow is a bit exceptional even within this group: it not only uses tools, it manufactures them. The crow can pry off a twig and shape it into just the tool it needs. Watch the process in this video: the crow realizes it needs a tool, makes the tool, and then figures out the best place to use it!

Unfortunately, Hawaiian crows became extinct from the wild in 2002 as a result of disease, predation, habitat encroachment, and shooting by farmers who saw them as a threat to their crops. They have been bred in captivity since then in hopes of reintroducing them to the wild. The success of reintroduction is not assured, especially since rising temperatures have allowed mosquitoes that carry bird malaria to thrive in the higher altitudes of Hawaii where the crows once lived. Nevertheless, six fledglings will be released into the wild this November, and you can read about and follow the process here.

There are many reasons to care about the Hawaiian crow and its survival, and one of them is that the species can help us understand something very interesting about the relationship between humans and nature. One of the many early assumptions about the differences between humans and animals was that only humans use tools. Over the last few decades, scientists have discovered tool use among a diverse set of animals: from sea otters that use stones to open abalone shells to bonobos that use leaves as umbrellas to elephants that use branches to swat flies. There is much to learn about the parts of the brain that allow such complex abilities as tool use and when, where, and how tool use is taught rather than instinctive.

And for those of us who aren’t scientists, there is the simple sense of awe that comes from learning what animals can do and how much like us they can be. I hope someday to watch a video of wild Hawaiian crows using tools and showing us their genius, adaptability, and determination.

Monday, October 17, 2016

Back from the Brink

I was just skimming over my nature notes from this time last year and recalled an amazing week. It was a busy week, and I couldn’t have spent more than 40 minutes total walking outside. But in those 40 minutes walking up and down my country road, I saw three amazing things: a bald eagle, a mink, and an eight-point white-tailed buck deer. Why is that so amazing? Because all three species have been pulled back from the brink of extinction thanks to concerted human effort.

"Bald Eagle Head 2" by Tony Hisgett CC BY 2.0.
The sight of a bald eagle is still a thrill for me because I remember a time when it was such a rare sight. Now the bald eagle is listed as “least concern” and “population increasing” and has been taken off the endangered species list, with over 6,000 breeding pairs in the lower 48 states. Their endangerment was caused by a whole host of factors: habitat encroachment; poisoning by DDT, lead shot, mercury, and other toxins in the prey eagles consumed; and shooting by ranchers and others who considered them a pest. Some of these explanations are considered controversial, as are all claims by environmentalists that threaten an industry or way of life, but what is clear is that a combination of efforts taken over the last decades has worked well. Federal and state agencies and individuals have worked hard to protect habitat, outlaw the shooting of eagles, and reduce use of toxins, and will continue to do so in order to ensure the bald eagle survives.

"An American Mink in Capisic Pond, Portland,
ME" by Chuck Hemler CC BY-SA 3.0
By the early part of the 20th century, wild mink were in trouble because of the demand for their fur. This conservation story is a mixed-happiness one: the wild population was saved because of the increase in mink farming. Mink farming is not a nice industry, and the animals are subject to a great deal of cruelty. Mink were farmed in the U.S. and then exported to Europe, what was then the U.S.S.R., and South America to fill the high demand worldwide for mink fur coats. Escapees from mink farms outside the US are now an invasive species, out-competing other native small mammals and reducing bird populations through egg predation. In the U.S., mink farm escapees, bred to be smaller and have thicker pelts, are changing the genetics of the wild population, which may have important long-term effects. But for now, this story shows that, when we stop over-hunting a wild population of animals for whatever reason, the population has the potential to rebound quickly and stabilize.

"Whitetail Deer" by Garett Gabriel CC BY-SA 3.0
And the white-tailed deer. It is hard to believe today, but that population was in severe decline by the end of the 19th century due to hunting for meat and buckskin by Native Americans and settlers of what was then a relatively small population, as well as the removal of food sources through heavy logging in forests. There is historical evidence of concern for deer populations; one New York locale had deer laws as early as 1788 that established a season for deer hunting! Throughout the first half of the 20th century, feeding of deer combined with limits on both season and numbers brought the population back. The clearing of forests ultimately aided the deer, as it provided edge habitat - the meeting of forest and field - that deer prefer. Now, of course, the white-tailed deer population is too big, and they have become pests: harming agriculture and private gardens, destroying new growth in forests, and decimating the habitat of birds and other animals, not to mention causing car accidents. Now many forest and wildlife conservation efforts include the hunting of white-tailed deer.

"American Bald Eagle" by rightclicks
CC BY-SA 3.0
What seems to me to be the most important common denominator in these stories is a change in culture. Conservation efforts are the nuts and bolts of the rebounding of endangered populations, but most important of all, they change our mentality about the importance of animals. Eagle poaching began to decline in part because of stiff financial penalties, but today I’m certain it is kept in check because people have come to see the bald eagle as a somewhat sacred symbol of our national identity. Trapping of minks, beavers, and other animals have declined as the demand for furs and pelts have declined; even mink farming is on a downward trend. And hunters have become some of the best conservationists over the course of the 20th century, realizing that animal populations and their habitats must be managed carefully in order to ensure that the sport of hunting can continue. (In fact, I would argue that we need to encourage more of a hunting culture in this country.) Now we must turn this concerted human effort toward other species facing extinction, and that will be the subject of my next blog.