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I was one of those boys who became an adult during the 1960s. Looking back, we think of those as turbulent times because of Vietnam and all the demonstrations and disruptions associated with an unpopular war. As a college student during the end of that decade, I had to deal with whether or not I felt strongly enough about things to participate in antiwar demonstrations, and when I graduated from college in 1971, I had to live through several uncomfortable months as I waited to see if my draft lottery number would force me to become part of a war effort that by then was obviously winding down. (Fortunately, it didn't.)
As someone who started birdwatching while in elementary school and got a banding permit while still in high school, the 1960s were an exciting and turbulent time for other reasons. In 1962, Rachel Carson published her book Silent Spring, which suggested that the use of persistent pesticides such as DDT would lead to environmental devastation if continued at the levels common at that time. The importance of this single body of work in the development of the environmental movement is hard to estimate. I remember reading it first as a 12-year-old when parts of it appeared in the Des Moines Register; I certainly cannot remember anything else I read at that age that affected me as much.
Although numerous attacks on both the detail and the tone of Silent Spring occurred, and some of them were justified, too many pieces of evidence supporting Ms. Carson's thesis were appearing in the news to make Silent Spring go away. Bald Eagle (Haliaeetus leucocephalus; note that scientific names for Neotropical migrants are listed in the Appendix), Peregrine Falcon, and Osprey populations were declining rapidly, apparently because they were laying eggs with thin shells as a result of high DDT residues in their bodies. In the Midwest, where DDT was used to try to control the beetle that spread Dutch elm disease, many towns were losing not only their elms but their populations of American Robins as well. I will never forget the ritual of spring on the Iowa State University campus during the late 1960s. The robins would appear all over campus, set up territories, then start to die. By the end of the decade, only a few nests could be found, where literally hundreds had occurred before DDT.
So many observations suggested that something was wrong in the environment that many people did not believe those representatives of governmental agencies or big business who said that DDT was at best harmless or at worst a positive and cost-effective insecticide. I have often wondered how much the war-related turmoil of the 1960s aided the developing environmental movement; if government and big business would lie to us about how and why a war was being fought thousands of miles from home, why would they hesitate to lie about something as trivial to them as potential side effects of a pesticide?
The use of DDT in the United States was banned in 1972 (but it is still produced in the United States and exported in vast amounts). The recovery of those birds that were most obviously affected by DDT has been phenomenal. Despite warnings about the long-term effects of something with a half-life of around 10 years, robins are thriving throughout the Midwest, and the large raptors are coming back in impressive numbers. The Bald Eagle is off the endangered species list, and Ospreys are abundant. Peregrine Falcons are recovering more slowly (perhaps because they are still accumulating DDT on their tropical wintering grounds), but with the help of extensive restocking programs they are much more abundant than during their nadir.
Although all was not rosy on the environmental front during the rest of the 1970s and 1980s, for people whose focus was bird conservation in North America, this period seemed to be one of quiet progress. Those species that suffered the most from DDT seemed to be recovering rapidly, while most everything else seemed to be doing fine. There were species of concern, particularly those with limited populations and/or habitats; for these the Endangered Species Act was developed, which seemed as effective an approach to saving an endangered species as one could get.
This feeling that things were going well in the North American bird world was broken in the late 1980s. Several scientific discoveries that were counter to an "all's well" approach to avian populations appeared, and the patterns suggested by these studies were expanded in several articles, written for popular audiences, that painted a dire future for many North American bird populations.
The biggest scientific discovery that fueled a sense of doom was that of Chandler Robbins and his colleagues, who analyzed Breeding Bird Survey data for the period 1966-1988 and found that numerous species showed significant national declines during the period 1979-1988 (Robbins et al. 1989b). Most important, the species showing the most pronounced declines were those that winter in the Tropics of Central and South America and the West Indies. About this same time, numerous studies of so-called habitat fragmentation were appearing, nearly all of which showed that many species did not occur in remnant patches of habitats that at one time were more widespread, even when these patches were relatively large. Nearly all these studies agreed that the birds most affected by fragmentation were those that wintered in the Tropics. Concurrently, numerous studies detailed the loss of forest in the Tropics, with emphasis on loss of rain forest.
It didn't take a genius to start seeing a pattern in the above. Birds that wintered in the Tropics were declining at the same time that tropical habitats were disappearing. Soon, popular articles appeared, suggesting that the loss of the Tropics was causing declines in those birds that breed in North America and winter in the Tropics and featuring titles such as "Silent Spring Revisited," "'Future Shock' for Birders," "Empty Skies," "Death of the Dawn," and "Birds over Troubled Forests." The most complete discussion suggesting a bleak future for migrant birds was John Terborgh's book-length treatise Where Have All the Birds Gone? (Terborgh 1989).
It did not take long for the conservation community to take note of such dire predictions and to respond. An international symposium of scientists in December 1989 was followed by an international gathering of both governmental and nongovernmental conservationists in December 1990. At the latter meeting, the Neotropical Migratory Bird Conservation Program (also known as Partners in Flight) was started to ensure survival of migrant birds while there was still time. By 1996, Partners in Flight was calling itself "the most comprehensive bird conservation program ever launched."
Were things really this bad? Did we face an imminent disaster? Even in 1997, popular articles appeared that showed how confusing the situation could be. Just one day apart, the New York Times published "Something to Sing About: Songbirds Aren't in Decline" (Stevens 1997), and the Christian Science Monitor published "Requiem for the Songbird: Perilous Decline Puzzles Scientists" (Schneider 1997).
The truth is that understanding migrant birds in enough detail to understand what regulates their populations well enough to save them is a complex task, one whose details do not fit easily within the confines of a newspaper article or an environmental organization's pitch for funds. In this book, I give an overview of how our concern about migrant birds came to be, what we need to know in order to save migrant birds, and what is currently being done. Although it is hard to fault an international conservation plan that is now focusing on virtually all birds, Partners in Flight is not without its controversies. The people who believe that breeding-season problems are at the root of declines argue with those who favor wintering-ground limitation, while those who think migration habitat may be critical feel they are being ignored. Managers want to manage now, while researchers (myself included) often argue that we don't know enough. At the extreme, we must ask if the evidence regarding declines of migrant birds is compelling enough to merit the most comprehensive conservation plan in history? Do we truly face a future of empty skies and silent springs? Are all migrant birds facing a similar future, or is our future one of different skies and different-sounding springs? Even if the evidence for declines is compelling, do we know enough about how migrant bird populations are regulated to design meaningful, effective conservation plans for them, recognizing that these may require multinational efforts?
I discuss these and other questions in this book, in many cases pointing out where the knowledge we need is missing and how it can be gathered. Along the way, I hope to provide insight into how science works (and sometimes doesn't work) and how the transition from science to management is not always a smooth one. The many ways that dedicated biologists work so hard trying to figure out how to save birds are also noted. Finally, and important, I hope to introduce the reader to many of the wonderful adaptations that characterize migrant birds; they truly are an amazing group of birds, without whom springtime in the New World Temperate Zone would not be the same.