Birds in North America are in trouble. There is no question, at this point, that we must have a complete analysis of what is causing the rapid decline in bird populations. The current explanations of this problem are incomplete and misleading.
The Audubon Society released the results of a major study in 2007. This comprehensive study shows that even common birds are in rapid decline and now on the path to extinction. As a follow up to the Audubon study and other alarming reports, this is a brief about one of the major causes of this disaster. Included in this study are clear explanations why entrenched attitudes and assumptions, flowing from an important event in our nation's history, are playing such a decisive role in the current crisis.
The numbers and break-down at the end of this report are so shocking that the public is not going to believe that the biggest, by far, cause of bird mortality is not being adequately studied or managed. It is all but certain that we wi ll need new museums with wax figures and recorded vocalizations so our children can enjoy the sights and sounds of the bird species that appear to be destined for extinction. If you consult the prominent bird experts in America, you will find that there are just two main causes of the dramatic decline of bird populations.
The two main problems are believed to be the loss of habitat and global warming. The problem with this analysis is that bird populations are falling much faster than the loss of habitat can explain. Statistics on habitat loss can be quite misleading. Replacing a large area of desert Sage Brush with irrigated farmland is not a loss, but a tremendous gain, as far as most birds species are concerned.
This will still be categorized as "human encroachment" regardless of the actual impact on birds. In addition, there is the glaring fact that there are many more birds and more bird species, not fewer, in much warmer latitudes where average temperatures soar dramatically higher than any possible global warming scenario could ever produce in regions farther north or south. There must be another major factor, but there is no evidence to date of a deadly new pesticide or some other cause of widespread poisoning. Birds are simply vanishing. What causes birds to just disappear?
This study is about the bird species that have been rapidly increasing in population while other species are disappearing. Of course, many of the professionals in this field know what's going on, but this particular subject is a large and vocal elephant in the room that creates a real dilemma for bird experts. There are obvious reasons why this subject is difficult to deal with.
The main cause of the frightening decline in the populations of some bird species is a thirty year population increase of certain predator bird species. The next decade will confirm this analysis with heartbreaking finality. This report is an invitation and challenge to all bird experts to improve on this study with more extensive research on raptor populations. As you can see in the chart, even estimates based on the most conservative numbers possible, are beyond shocking.
Since this subject is abhorrent to the vast majority of professionals in the field, and to be avoided at all costs, it is important to know what is behind the prevailing attitude that has led to this unfolding disaster. Surely, behind the scenes, there must be at least a few experts trying to come to grips with this problem, but there is certainly no attempt, at this point, to honestly communicate critically important information to the public. There is a fascinating historical and social reason why the inclination to ignore this aspect of the decline in bird populations is so powerful and so prevalent.
There is, of course, widespread agreement that there has been a population explosion of many varieties of hawks, falcons, and owls for the last thirty years. The only thing the public usually hears about, however, are the very few raptor, or "birds of prey" species, that are in trouble. As you will see in this report, many of the other raptor species, especially the ones who's diet consists of other birds, have been dramatically growing in number since the ban of DDT in the 1970s. I
t is very easy to demonstrate the level of public awareness on this issue. Ask anyone you run into a simple question. How many birds are killed by other predator birds, on a daily basis, just in the United States and Canada? You will find that the low answers are around "50 birds," and the high answers are around "2000." The actual number of daily bird kills by birds of prey, hawks, falcons, and owls, just on the North American Continent, is almost impossible to comprehend. Based on conservative numbers, that include all of the major factors, the low end estimate is well over 4 million birds killed every day.
During the breeding season in the summer, the daily bird kills are well over 7 million per day - at a minimum. This is not a worldwide calculation. This is just the US mainland and Canada. Because of limited knowledge of current populations, especially of the illusive bird eating Accipiter varieties, the high end estimate of daily bird kills could easily be double for both of these staggering figures. Baby birds, still in the nest, and fledglings just out of the nest, are a primary food source for virtually all varieties of hawks, falcons, and owls. Red-tail Hawks, Broad-wing Hawks, and many other varieties who normally have difficulty catching adult birds, are death on nestlings and fledglings all through the spring and summer.
The percentage of birds in their diet skyrockets during these months. Eagles, on the other hand, because of their size and diet, are not a major factor in bird mortality. I am hoping there will be growing pressure to conduct well funded studies that will produce official estimates based on research in areas that have been incomplete and sketchy up to now. Raptor population estimates available to the public are from the 1990s!
A careful study at banding stations could produce valuable population estimates. We know that over 50,000 Cooper's Hawks, and 38,000 Sharp- shin Hawks have already been banded in the past. How many of the hawks trapped for banding purposes each year are already banded? If the number is less than 1% as some have indicated, then the currently published population estimates of these two species are ridiculously low.
Continuing to underestimate the population of both the Cooper's and the Sharp-ship hawks will prove to be catastrophic. There were States that warned the Federal Government about protecting the hawks that live off of song birds. These two varieties are bird killing machines responsible for a minimum of 1,215, 000 bird kills per day in North America alone.
It is more than double this number for the breeding months of June and July while they are feeding their young. Again, these kill numbers are based on outdated population estimates which may be much to low. The number of breeder pairs per square mile could be checked in different regions to help us assess the total.
Since the average clutch size is about 4 eggs per nest for these two species, we simply cannot afford to underestimate their populations. While there are still a few predator species that are themselves in trouble, there are other varieties who's populations continue to soar. The failure to make this simple distinction is leading quickly to a nightmare scenario that is potentially irreversible. For some of the more vulnerable bird species, with open-cupped nests in forested areas, it is probably too late. In order to have any hope whatsoever of at least preventing some of the extinctions in the future, it is critical that t he background of certain beliefs and attitudes are understood.
This is an informal study by an individual. I have been a passionate bird lover since age five. I started checking out all the bird books in the library at a very young age, and have never stopped. Collecting the books and documentaries is even better. Managing a loft of homing pigeons during my teen years was a life-changing experience that contributed greatly to my successes later on. Even though my degree is in philosophy and my career is music education, my love of birds has been life-long. The first time I saw pictures of parrots as a child, I simply could not believe they were real.
My frame of reference at the time was for the most part Sparrows, Robins, and Seagulls. Parrots, with their florescent coloring, were simply too beautiful to be real. There is actually a direct connection to this childhood experience and why I am publishing this study. I did not enjoy, to say the least, finding out that the complete destruction of the beautiful Puerto Rican Parrot was caused primarily by a saturation population of Red-tailed Hawks.
This was studied and confirmed but nothing, to my knowledge, was ever done about it. All bird lovers of course love Red-tailed hawks, but on the other hand, we do not like the total destruction of a magnificent Parrot species. In this case, a few parrots in Puerto Rico were taken into captivity to prevent total extinction but the natural population was all but destroyed. There is a clear cut and understandable reason why this tragic scenario in Puerto Rico has turned out to be a prophetic picture of what is now happening on the North American Continent.
During the late 1960's we took dramatic action as a nation to save Bald Eagles, Peregrine Falcons, and a few other raptor species from the damage that was being done by DDT. Their eggs were thin shelled and often would not hatch. Implementing a ban on DDT eliminated the problem that was damaging the reproductive process. Saving these majestic birds from possible extinction was a national triumph and an example for the whole world. These awesome birds have been admired throughout history by almost every culture, but the process of watching their recovery has added an entirely new dimension to this powerful, and yes, emotional bond. Try bringing up the subject of how the current population explosion of the various raptors, or birds of prey, might be affecting other birds, and you will quickly see what I mean.
You should also try asking for information from bird experts after telling them you are studying this subject! Be sure to keep a list of all the phone calls and e-mails that are ignored. There is an all pervasive assumption in our culture that there cannot possibly be too many birds of prey. We don't even question our belief that more and more Falcons, hawks, and owls are glowing tributes to our great success in saving them. In addition, and most dangerous of all, everyone has the general impression that all of the various raptor populations are always in trouble. Nothing could be farther from the truth or more dangerous to the bird species that are in trouble. Our entire nation, for good reason, has fallen in love with these magnificent "birds of prey."
The books and documentaries are coming in an endless stream. From a personal standpoint, the more I study these birds, the harder it is to deal with the subject of what they do for a living. Imagine how hard it must be for professionals in the field who work directly with these birds continually. The examples are endless that illustrate the difficulty that experts are having in terms of being objective and impartial.
Here are just a few of the more striking illustrations. The main government agency in charge of protecting birds, the Fish and Wildlife agency, publishes what appears to be a complete list of all causes of bird mortality. You will never guess what is completely missing. Yes, the biggest cause of bird mortality. Also, there are various studies of the decline of the Band-tailed Pigeon, right next to studies of the annual population increase of the Cooper's Hawk, who's diet, by the way, is made up of about 90% birds. Even though these two natural enemies often share the same habitat, you will not be able to find anyone who is willing to state the obvious.
Yes, if you throw Piranha into the fish pond, the Goldfish will disappear. Increasing the number of appeals to the public for more donations in order to study global warming might be just a little bit off course. As a backdrop to how this is being managed, keep in mind that millions of dollars in taxes are being spent annually to change the laws regarding the wind-turbines that generate electricity. Wind-turbines kill birds. The estimates vary dramatically, depending on how hysterical the source, but it is realistically somewhere around an average of 50 to 100 bird kills per day in the USA.
If this is discussed in isolation, without any perspective whatsoever, people get very upset at the thought of losing 100 birds a day. However, wind-turbines, with moving blades, will forever be one of the most insignificant causes of bird deaths. Birds are always alerted by movement. A moving object is the very last thing a bird will fly into. The relatively few deaths that do occur are because of limited visibility in fog or darkness. If saving birds was the real concern, and not collecting huge fines from power companies, wind-turbines would be the least of our worries.
Household and feral cats, on the other hand, are a major cause of bird death. Some of them have a regular routine of killing birds. Since there are well over 40 million cats, in North America alone, you would think that everyone would agree that wind-turbine kills are off the chart - the bottom of the chart. High tension electrical wires, which are motionless and sometimes hard to see, kill thousands of birds every day. Glass windows in buildings and homes may be even worse.
The purpose of this brief, however, is not to list the common causes that everyone else lists regularly. In light of rapid declines in bird populations, it is inescapable, regardless of how unpleasant, that we must improve our understanding of the number of birds that are being killed by predator birds. Even conservative estimates show that no other cause of bird mortality comes remotely close to 4 million plus daily bird kills. If it helps to make things a little less upsetting, picture a pile of 100 tennis balls that represent the daily kills from wind-turbines.
Now picture, if you can, a pile of 4 million tennis balls. You would have no trouble storing 4 million tennis balls as long as you have 50 extra bedrooms in your home - packed from floor to ceiling. It would take 87 bedrooms to store 7 million tennis balls. Yes, enough to fill your average Hollywood home. Exactly how far from reality is public awareness on this subject? I am recommending that an official nation wide poll be taken to highlight this shocking disconnect.
A facility that rescues 2,000 wounded birds will destroy all of this work if they save just one Cooper's Hawk in the process. My personal opinion is that there will be a number of extinctions before there are any significant changes in attitudes or policies. The urgency in all of this is driven by simple facts of nature.
Raptors, for many reasons, dominate in the wild. For some raptor species, the only major factor that seems to limit their population increase is the availability of food. This has alarming implications because there are a few predator bird species with huge populations that live primarily off of other birds. It is certainly true that there are many people who care much more about hawks, falcons, and owls than they care about song birds or any other kind of bird. There is, however, a terrible irony in all of this if attitudes stay the same as they are now.
As birds continue to disappear in large numbers, the main food supply for some raptors will also disappear. The very same raptor species we rescued in the past will starve to death in mind-boggling numbers. There is also the possibility of a major swing of the pendulum in public opinion if we lose too many bird species. In England, the Red Kite was government protected for two hundred years.
The resulting over-population of this hawk became such a nightmare that the whole country turned against them and completely wiped them out. Only a few pair survived off of the island in Wales. Can too many wolves wipe out the populations of other animals? The answer is well known. Can too many raptors wipe out bird populations to the point of extinctions?
The experts cannot tell you because they refuse to consider the problem. Let's avoid, at all costs, blind assumptions and extreme positions that will inevitably lead to a major catastrophe. The chart below is based on the "Land-based Population Estimation Database." The estimate, on the Cooper's Hawk only, has been updated based on FWS and Cornell studies.
Cornell University has done extensive research on all North American bird species. I highly recommend membership for their website "The Birds Of North America Online." The information below, in relation to average sizes and dietary habits, is from various Fish and Wildlife and Cornell University studies. The formula used in this chart is designed to provide a general picture of daily bird kills by the predominant predator bird species in North America.
(1) average size between male and female (2) daily food intake based on 28% of body mass for raptors in the wild (3) analysis of diet with the average percentage of birds consumed (4) average bird oz. consumed multiplied by the estimated population (5) total bird ounces consumed daily divided by the average prey size (6) Summer kill surge based on 2.5 nestlings and 70% of adults breeding Daily number of birds killed by Hawks, Falcons, and Owls in the USA and Canada = 4,308,100 BIRDS During June and July = 7,537,005 Birds Killed Daily
Statistics Table Removed Due To Excessive Lenght...Publisher