biodiversity conservation biology

Galápagos Hawk

Galápagos Hawk


“… the introduction of any new beast of prey must cause [extinction] in a country, before the instincts of the indigenous inhabitants have become adopted to the stranger’s craft or power.”

Charles Darwin


We had just seen a Galápagos hawk soaring overhead when we heard an incongruous sound; here were cats mewing beside the path. I caught a glimpse of a tabby kitten with the bluest eyes.

“I like cats” the guide said “but I’ll have to report these to the rangers. They will come here with dogs.”

We were returning from hiking on the tortured volcanic surface of one of the world’s largest active calderas, Cerro Negro, on Isla Isabela. We walked carefully along the border of the volcano’s crater; the path was narrow and muddy with a fatal drop-off. Fortunately there was a slender border of green between the sheer wall and us. This is where these feline invaders lived.

Cats are an exotic species in the Galápagos Islands, maybe introduced to catch the rats that were also introduced accidentally by man. Sometimes biocontrol (using one species to control another) works out well, but other times it is a disaster. Cats in the Galápagos are a disaster. Darwin recognized this danger almost two centuries ago.

Galápagos hawks only live on that isolated group of islands; they are endemic, meaning they are found nowhere else in the world. They nest in low trees and in the hollows of walls of the volcanic rock of which the islands are made. Formerly the hawks had no natural enemies but now their eggs, nestlings and fledglings are easy prey for cats.

A census of Galápagos hawks taken late in the 20th century estimated fewer than 1000 individuals. These magnificent birds have been eradicated from much of their former habitat so now this species is found on only four of the islands. The Red List of Threatened Species states that these hawks are vulnerable to extinction because of introduced predators and their small population.

Of the six ways that mankind sends other species to extinction, perhaps introduction of exotic plants and animals is the second most common.

Exotics may not seem so bad since our homes and gardens are filled with beautiful plants from other lands. Unfortunately they can cause problems in at least three ways. Exotics may outcompete natives. They often don’t have local pests to help control them, as is the case with cats in the Galápagos. Pollinators often find exotic plants unattractive so pollinators become scarce, but they are essential to native species.

Ecuadorians are doing a fine job of dealing with exotic species. We paid $100 for a permit to visit the Galápagos; that money helps fund the rangers and other efforts to protect the unique environment. Our small group of “adventure tourists” also was given an orientation urging us to respect this amazing place with its many endemic plants and animals.

Destruction of habitat and climate change are two other ways that humans are causing the mass extinction of species. As the numbers of humans has grown, and as we “improve” the landscape with more agriculture and construction, there is simply less space for other species. Not only do we use more and more of the land, but also we break up what there is so it is of less value to critters.

Climate change is also wreaking havoc with many plants and animals. Species that need cold, or whose pests are controlled by cold, are susceptible to our climate’s warming. A local example is the little pikas that live high in the mountains. They are happiest with cold winters and lots of snow. They can move up in altitude as the world warms, but our mountains only go so high. If the world gets too hot they will all “go to heaven”. Another example is the spruce bark beetle, which has killed so many of our spruce trees. Sub-zero temperatures and adequate moisture have controlled this pest in the past, but the beetles are thriving with climate change and drought.

There is hope for endangered species, at least in the Galápagos. Efforts to protect their endemic hawk have apparently been successful because I have heard that there are now almost 2000 members. There are even plans to reintroduce them to islands where they had been driven to extinction. I feel good that our small contributions paid for by the permits to enter the islands have been effective in helping to preserve one of nature’s many wonders.

© Richard Grossman MD, 2013

Carrying Capacity Environment

Stick to Humor, Dr. Black

Stick to Humor, Dr. Black

“…the first essential component of social justice is adequate food for all mankind.”

Norman Borlaug, in his 1970 Nobel Peace Prize acceptance speech


            I used to love to listen to Baxter Black on the radio. I admired his sense of humor and his human insight. Then I read an article he wrote.

“What is sustainable ag?” appeared in the March, 2013 issue of Western Farmer-Stockman. I am writing this as a response to my friend Al, who clipped the article for me. Al is a wise man and an experienced farmer. He wrote: “I thought this was a good article on sustainable agriculture. I hope you find it interesting.”

Indeed, it is interesting—not for what it contains, but for what Dr. Black left out. First, let me summarize the article.

Dr. Black writes that that most agriculturalists think that “sustainable farming” is a joke, and derides those who want to return to pre1950 farming methods. He makes fun of “hobby farmers” who have a garden and a few animals since they don’t produce enough food to feed their families for even two weeks.

Black then rightly recaps the history after World War II, when world population soared and people worried about food shortages. Megacorporations and scientists were able to increase food production remarkably, despite the creep of cities taking over productive ag land. He doesn’t mention the “green revolution” of Dr. Norman Borlaug and others, which is credited with saving over a billion lives by developing highly productive strains of crops.

This modern, industrial model of agriculture is sustainable according to Black, because it can sustain so many people. Great grandpa’s old-fashioned ways of producing food are laughable in today’s context, he writes. He would prefer the term “subsistence-level farming”.

Although I understand Al’s and Black’s viewpoint, I cannot agree. My concern is that, along with its good, the “green revolution” has had several dreadful unintended consequences.

Growing highly productive plants and animals requires the use of many chemicals that are made from limited resources, and are toxic. The chemicals include fertilizers, insecticides, fungicides and herbicides. They are all derived from fossil fuels, and all transported with fossil fuel. Unfortunately, supplies of carbon-based fuels are limited. We have probably already maximized the production of petroleum and soon will see its decline—and a rapid increase in prices.

We are starting to realize the subtle toxicity of many of the agricultural chemicals. The wonder insecticide of my childhood, DDT (which I was told was entirely safe) turned out to be an ecological disaster and now is banned in many countries. An amazing group of insecticides, neonicatinoids, is probably responsible for the die-off of our honeybees—colony collapse disorder. Since bees pollinate so many crops, this is an agricultural disaster.

We now realize that many agricultural chemicals have endocrine effects, even in minuscule concentrations. Just a pinch in all the water in an Olympic swimming pool can cause harm! Insecticide residues may decrease sperm counts. One common agrichemical, atrazine, has been shown to cause feminization of male frogs and has been implicated in reproductive cancers.

The seeds of highly productive plant strains must be bought from corporations that control their prices. In the past, seed grain was carefully preserved from the prior crop, but now farmers need cash—or credit—in order to buy seeds. This expense, along with the cost of the chemicals, has broken many farmers. In a good year they can make a living, but in a bad year their suicide rate climbs.

Finally, modern agriculture depletes our soil. The use of chemicals exhausts many components that help plants grow.

There is a subtle chicken-and-egg situation here. Modern agriculture has increased food supply, which allowed our population to swell. Borlaug outwitted Malthus, who predicted that human population would be limited by starvation from lack of food.

Here is the quandary: does modern agriculture only provide a short-term gain? As we deplete petroleum and as crop growing conditions worsen from climate change and drought, can the amazing technology of modern agriculture be sustained? Indeed, some scientists have a terrible vision of severe food shortages with bloodshed and more deaths than Borlaug’s green revolution saved.

In his Nobel Prize speech quoted above, Borlaug also said: ““Most people still fail to comprehend the magnitude and menace of the ‘Population Monster’.” Hopefully Herald readers are better informed than most. But only time will tell if Dr. Black is correct about sustainable agriculture, or if he should go back to being a humorist.

© Richard Grossman MD, 2013