RACING PIGEON DIGEST  

BIRD EXTINCTIONS INEVITABLE, OVER 4 MILLION BIRD DEATHS DAILY  

By Mark Almond  

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 break­down 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 will 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 they list 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 farm land is not a loss, but a tremendous gain, as far as most bird 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 warmi ng 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 poison' ing. 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 d isappearing . Of course, many of the professionals in this field know what' s going on, but this particular subject is a large and vocal elephant i n the room that creates a real dilemma for bi rd 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 speci es. 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, is 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 whose diet consists of other b irds , have been dramatically growing in number since the ban of DOT in the 1970$.  

It i s 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 worl dwide calculation. This is just the US mainland and Canada. Because of li m i ted 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 owl s. Red-tail Hawks, Broad-wing Hawks, and many other varieties that normally have difficulty catching adult birds, are death to 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 thei r size and diet, are not a major factor in bird mortali ty.  

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 al ready banded? If the number i s less than 1 % as some have indicated, then the currently published population estimates of these two species are ri diculously low. Continuing to underestimate the population of both the Cooper's and the Sharp-shin 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 kil l numbers are based on outdated population estimates which may be much too 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 four 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 whose populations continue to soar. The failure to make this simple distinction is leading quickly to a nightmare scenario that  

PA G E 45  

is potentiall y irreversible. For some of the more vulnerable bird species , w i th open-cupped nests in forested areas, it is probably too late. In or der to have any hope whatsoever of at least preventing some of the extinctions in the future it is critical that the back ground of certain beliefs and attitudes are understood.  

This is an informal study by an individua l. 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 duri ng 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 par t Sparrows, Robins , and Seagulls. Parrots , with thei r florescent coloring, were si mply toe:> 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 pr imarily by a saturation population of Red-tailed Hawks. Th i s was studied and confi rmed but nothing, to my knowledge, was ever done about i t. All bi rd 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 exti nction but the natural population was all but destroyed.  

. There is ?- 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 DOT. The i r eggs were thin shelled and oft en would not hatch. Implementing a ban on DOT 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 cul ture , but the process of watchi ng their recovery has added an entirely new di mension to thi s powerful, and yes, emotional bond. Try bringing up the subject of how the current population explosion of the various raptor~, or birds of prey, might be affecting other birds, and you. will quickly see w ~at I mean. You should also try asking for Information from bird exper ts after tell i ng them you are studying thi s subject! Be sure to keep a l ist of all the phone calls an~ e-ma i ls 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 beli ef that mor e and more falcons, hawks , and ow ls are glowi ng tributes to our great su ccess in savi ng them. In addi t i on , and most dangerous of all, everyone has t he gener al i mp r ession that all of the various raptor populations are always i n trouble. Nothing could be farther from the truth or more dangerous to the bird species that are in trouble.  

Our enti re nation, for good reason, has fall en in l ove wi th these magnificent " birds of prey." The books and documentaries are coming in an endl ess stream. From a personal standpoint , the more I study these birds, the har der it is ! o 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 wi th these bir ds continually. The examples are endless that illustrate the diffi culty that experts are having i n terms of being objective and impart ial. Here are ju st a f ew of the more striking illustrations. The main government agency In charge of protecting birds, the Fish and Wildl ife agency, publishes what appears to be a complete list of a ll causes of bird mortality. You will never guess what i s completel y  

 

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, whose di et , by the way, is made up of about 90% b i rds . Even though these two natural enemies often share the same habi tat , you will not be able to find anyone who is willi ng to stat e the obvious. Yes , if you throw Piranha i nto 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 t o how. this is being managed, keep in mi nd that millions of dollars In taxes a re bei ng spent annuall y to change the laws regardi ng the wind-turbines that generat e elect ricity . 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 kill s 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, wind­turbines , w i th 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 i nto. The relat ively few deaths that do occur are because of li mited visibil ity in fog or darkness. If saving b i rds was the real. concern , and. not collecting huge fi nes from power companies, W i nd-tu r bines would be the least of our worr i es . Household . and feral cats, on the other hand, are a major cause of bird death. Some of them have a regular routine of kil ling bi rds. Si nce there are wel l over 40 million cats in Nor th America alone, you would think that everyone would agr ee that wind-turbine kil ls ar e of f t he char t - the bottom of the chart. High tension electrical wir es , which are motionless and sometimes hard to see, kill thousands of birds every day. Glass windows in buildings and homes may be even worse. 

PAG E 46  

  

Th e purpo se of th is bri e f , however , is not to li st t he com mo n causes t hat every one else l is t s regular ly . In li ght of r ap i d decli nes i n bi rd popul a t io n s , it is i nescapab l e , regard l ess of ho w unpleasant , that we mu st i mprove ou r un de r sta n ding of t he num be r of bi rds t hat are being kil led by pr e d ator bi rds. Even conservati ve esti mates show that no other ca u se of bird mortalit y comes remotel y close to 4 mil lion dail y bird kills. If it helps to make things a lit t le less upsetting, pictur e a pile of 100 ten nis ball s that represe n t the dail y ki l l s from wind-turbines. Now picture, if you c an , a pile of 4 milli on t enn i s balls. You wou ld have no t roub l e stor ing 4 milli on tennis ball s as long as you have 50 extr a bedr ooms in you r home - packed from floor to ceili ng . It wou ld tak e 87 bedr ooms t o stor e 7 mill ion t ennis balls. Yes, enough to fi ll your average Hol lywood home.  

Exactly how far from realit y i s publi c awar eness on t h i s subj ec t ? I am recommendi ng t hat an off ic i a l na ti on-w i de poll be taken to highli ght thi s shocking di sconnec t . A f acility t ha t rescues 2, 000 wounded birds will des t roy al l of thi s work if they save just one Cooper ' s hawk in the process. My personal opinion is that there will be a number o f extinct ions before there are any significant changes in attit udes or p o li cies.  

The urgency in all of this is driven by simp le facts of nature. Rapt ors , for many reasons, dominate i n t he wil d . Fo r some r aptor species, the onl y major fact or th at seems to li mi t the i r popul ation increase is t he avail abi li ty of food. This has al a r m i ng i mp li cat i ons b ecause th e r e are a f ew pred ator bi rd speci es wi t h h u ge popul a ti ons that liv e primarily of f of ot h e r bi r ds. It is certai n l y t rue that there are many peopl e who care mu c h more about hawks, falcons , an d owls t han they care about song bir ds or any other kind of bird. The r e is, however , a terrible irony i n all of this if att itudes stay the same as they are now . As bi rds continue to disappear in large numbers , the main food supply for some raptors w ill also disappear. The very same raptor species we rescued i n the past will starve to death in mi nd-boggling numbers. There i s also th e possibil i t y of a maj o r swing of the pendul um in publi c opi n i on if we lose t oo many bird speci es .  

I n E n g l and , the Red Ki te w as gov e rn men t p r o t ec t ed for tw o hundr ed years. The r esu ltin g ov e r- pop u lat i o n o f t h is hawk became su c h a ni g ht ma r e t hat t he wh ole country turned against t hem an d compl ete l y wi ped th em out . Only a few pai r survi ved off of the island in Wales. Can too many wolves wi pe ou t the populations of other animal s? The answer is well known. Can too many raptors wipe out bird popu lations to the poi nt of exti nctions? The experts cannot tell you because they refuse to consi der the pr oblem. Let' s avoi d , at all costs, blind assumptions and extr eme positions t hat wi ll i nevi t ab l y lead to a major cat ast r ophe .  

The ch a r t below is based on the " La n d - based Pop u l at i on Esti mat i on Database." T h e esti ma t e , on th e Cooper ' s h a w k onl y , has been updated based pri mar i ly on FWS and Cor n e l l stu dies . Co r ne l l U n i ve r s it y has don e ext e n s i ve resear c h on all North Ameri can bi rd speci es. I high l y recomme nd membership for thei r webs it e " The Bir ds of North Amer i ca Online. " The esti mates below, in relati on t o si zes and di e t ary habi ts, are reasonable averages combi n i ng st udies and insights fr om different sou rces. The most ext e n s i ve r esearch reli ed u pon is from Cornell Universi ty , F i sh and Wildlife, and the fantastic book by Noel and Helen Snyder " Raptors of North America. " Th i s book makes a real contr i but i on in te r ms of research and balanced objecti v it y . No one, h o w eve r , seems wi l l i n g to ventu re ball -pa rk ave r ages i n th e ar ea of di e t a r y habit s . The esti ma t es below a r e off ered as a place t o b eg in . W h ile a fe w of the aver ages may tu rn out to be a littl e hi g h based on more research, the over a ll s tru ct u re of thi s c ha r t is desi g n ed to keep the kill es ti mates on th e l o w s i de . To pr event this topi c from being bogged down i n technicaliti es , minor factors, like bi rd ki lls due to f ata l inju r ies ( un s uccessfu l capture) and prey abandonment, have been excluded. There are plenty of bi rd experts out there with t he moti vat i on to find clever ways of di scred i ting thi s kind of stu dy. That is wh y the  

cha rt be l ow i s r ed u ce d to jus t the essenti al cor e element s f o r peop l e wh o can think for the m selves .  

Th e f orm ul a u sed in t hi s chart is desi gned t o pr ov i de a gen era l p i ctu r e of dai ly bird kill s by the predomi na nt p r e d ator bi rd species i n North A m e ri ca.  

( 1 ) ave r age si ze bet ween male and femal e  

( 2) dail y food intake based on 28% of body mass for raptors i n t he wil d  

(3) analysis of diet with the aver age per ce n tage of birds consumed  

( 4) aver age bir d oz. consumed multi pl i ed by the esti ma t ed popu lat i o n  

(5) total bir d ou nces consumed dail y di v i ded by th e aver age pr ey si ze  

( 6 ) S umm e r kil l s u rge based on 2.5 nestli ngs and 70%  

o f adu lt s br eed i ng  

Da ily n u mbe r o f b i rds k i l led by Hawks, Fa l con s,  

a nd Ow ls in the USA and Canada = 4, 308 , 100 BI RDS Duri ng June and Jul y = 7 , 537 , 005 Bi rds Killed Daily  

No r thern Goshawk - Pop. 200, 000 - Aver. Size 35 oz - Dail y Ki lls 86, 2 4 0 Birds  

S i ze 35 oz X dai ly i n t ake 28% = 9.8 oz X 55% b ir d di et = 5.39 bi rd oz  

5.39 bir d oz X pop. o f 200 , 000 = 1 , 078 , 000 bir d oz - div . 1 2 . 5 oz pre y = 86 , 2 4 0  

 

S h a rp -s h in Hawk - Pop. 1, 100 , 0 0 0 - Aver . Si ze 7 oz - Da il y Ki l ls 4 95 , 000 Bi r ds  

S i ze 7 o z X daily intake 28% = 1 . 96 oz X 92% b ir d diet = 1. 8 bi rd oz  

1 . 8 bir d oz X pop. of 1, 100 , 000 = 1 , 980 , 000 bir d oz - div . 4 oz pr ey = 4 95 , 000  

Coope r ' s Hawk - Pop. 1, 200 , 000 - Aver. S iz e 1 4 . 8 oz - Dai ly Kill s 7 20 , 000 Birds  

S i ze 14 .8 oz X daily inta k e 28% = 4 . 1 oz X 87 % b ir d diet = 3 . 6 bi r d oz  

3 . 6 bird oz X p op . o f 1, 2 00 , 000 = 4 , 3 2 0 , 000 bird o z - d i v. 6 oz pre y = 720 , 000  

pe re gr in e Falcon - Po p . 300 , 000 - Aver. S i ze 20 oz - Dail y Kil ls 14 2 , 500 Bi r d s  

Ave r siz e 20 oz X 2 8 % = 5.6 oz int ake X 95 % bi r ds = 5 . 3 2 bi rd oz  

5.32 bi rd oz X pop. of 300, 000 = 1, 4 25 , 000 bird oz - div. 1 0 oz prey = 142, 500  

Mer l in - Pop. 600 , 0 00 - Av e r . Siz e 7 oz - Da il y Kills 3 4 0 , 0 0 0 Birds '  

A v e r size 7 oz X 28 % = 1 .75 oz i n take X 95 % b ird s = 1 . 7 bird  

o z  

1 . 7 bird oz X pop. of 600 , 000 = 1, 0 2 0 , 000 bir d oz - div . 3 oz pre y = 3 4 0 , 000  

Kestrel - Pop. 4, 300 , 000 - Ave r . S i ze 4. 3 oz - Da i ly Kills 64 5 , 000 Birds  

S ize 4. 3 oz X dai ly int ake 2 8 % = 1 . 2 oz X 2 5 % bird diet = .3 bir d oz  

. 3 bird oz X pop. 4,3 00 , 000 = 1 , 290 , 000 bi r d oz - div. by 2 oz ave r . p r ey = 6 4 5 ,0 00  

G yrfalc o n - Po p . 50 , 000 - Aver. S iz e 40 o z - D aily K ills 16 , 8 0 0 Bi rds  

S ize 40 oz X daily intake 2 8 % = 11 . 2 o z X 60% b ird d iet = 6 .7 2 bir d oz  

6.7 2 bi r d oz X pop. of 50 , 000 = 336 , 000 bird oz - di v . by 20 oz aver. prey = 16 , 800  

  

  

P AGE 47  

P r a i r i e Fal con - Pop. 30 , 000 - Aver. S ize 27 oz - Dai l y Kil ls 7, 500 Birds  

S i ze 27 oz X dail y i ntake 28% = 7 . 56 oz X 40% bird di et = 3 bir d oz  

3 bird oz X pop. o f 30 , 000 = 90 , 000 bir d oz - di v . by 12 oz aver . p r ey = 7 , 5 0 0  

R e d-t a il e d Hawk - Po p . 2, 000 , 000 - Aver . Size 38.5 oz - Da i ly Kil ls 595, 00 0 Birds  

Size 38. 5 oz X dai l y intake 28% = 1 0 . 8 oz X 22% b i rd di et = 2 . 38 bi rd oz  

2.38 bi rd oz X pop . of 2, 000 , 000 = 4 , 760 , 000 bir d oz - div . by 8 oz p r e y = 595 , 000  

Broa d - w in g e d Hawk - Pop . 1 , 700 , 000 - Aver . Size 14 oz - Dail y K i lls 1 65 , 7 50 Bir ds  

S ize 14 oz X dai ly intake 28% = 3.9 oz X 1 0 % b ir d di et = . 39 bird oz  

. 39 bird oz X pop. of 1, 700 , 0 0 0 = 663 , 000 bir d oz - div . by 4 oz !J r e Y = 165,750  

Red-shouldered Hawk - Pop . 800 , 000 - Aver. S i ze 22 oz - D aily Kil l s 1 22 , 667 Bi rds  

Si z e 22 oz X dail y intak e 28% = 6 . 16 oz X 15% bird di e t = . 92 b i r d oz  

. 9 2 bird oz X pop. o f 800, 000 = 7 36 , 000 bi rd o z - div. by 6 oz ave r . p rey = 1 22 , 667  

Swa in son ' s H awk - Pop . 4 60 , 000 - Aver. S i ze 35 oz - Da i l y K i l l s 112, 700 Bi r d s  

S i z e 35 o z X dail y intake 28% = 9 . 8 oz X 20 % bird diet = 1 . 96 bird oz  

1 . 96 bird oz X pop. of 4 60 , 000 = 901 , 600 bir d oz - div. by 8 oz av e r. pr e y = 112 , 700  

N o r t h e rn Har r i e r - Pop. 400, 000 - Aver. Size 16 oz - D ai l y K i lls 53, 333 B irds  

S i ze 16 o z X da ily i nt ake 2 8 % = 4 oz X 20% b i r d di e t = . 8 bi rd  

OZ  

. 8 bird oz X pop . o f 400 , 000 = 320 , 000 bi rd oz - di v . by 6 oz aver . prey = 53 , 333  

R ough- l egged Hawk - P op . 300 , 000 A ver . S iz e 37. 7 oz - D a i l y Ki l l s 57 , 375 birds  

3 7 . 7 oz X da i l y intak e 28% = 10 . 5 oz X 14 . 5 % b ir d diet = 1 . 53 bird oz  

1 . 5 3 b i rd oz X pop . o f 300, 00 0 = 4 59 , 00 0 bird o z - div . b y 8 oz aver . p r ey = 57 , 3 75  

Har r is ' s Hawk - Pop . 40 , 000 Aver. S ize 34 oz - D a i ly Kill s 8, 4 44 b i rds  

3 4 oz X daily i ntake 28% = 9 . 5 oz X 20% bird diet = 1 . 9 bi rd  

OZ  

1 . 9 bird oz X pop. of 40, 000 = 76 , 000 bird oz - div. by 9 oz aver. prey = 8 , 444  

        __ ____ ____ _________ OWLS ___________________ _  

Great H o rn ed O wl - Pop . 2 , 000 , 00 0 - A ve r . S iz e 64 o z - D ai l y Kil ls 1 7 9 , 000 B i rds  

S ize 64 oz X d aily in take 28% = 17 . 9 oz X 1 0 % b ird diet = 1 . 79 bird oz  

1 . 79 bird oz X pop. 2 , 000 , 000 = 3 , 580 , 000 bi rd oz - di v . by 20 oz pr ey = 179 , 000  

Nor th e r n Saw - w het Ow l - Pop. 2, 000,000 - Aver. Size 3. 5 oz - Dail y Ki l l s 49 , 000 Birds  

Size 3. 5 oz X dai ly i n t a k e 28% = . 98 oz X 5% bird di et = . 049 bi rd oz  

. 049 bi rd oz X pop. of 2,000, 000 = 98,0 0 0 b i r d oz - div . by 2 oz aver . prey = 49,750  

Barn O wl - P op . 300 , 000 - A ver. Si ze 18. 6 oz - Da i ly K il l s 26, 000 B i rds  

S i ze 18.6 oz X dail y intake 28% = 5 . 2 oz X 1 0 % b i r d di e t = . 52 bir d oz  

. 52 bir d oz X pop. of 300, 000 = 156 , 000 bird oz - di v. by 6 oz a ve r . prey = 26 , 000  

B a r re d O w l - Pop . 600 , 000 - Aver . S ize 27 oz - Dai ly Kill s 84 , 750 Bir ds  

Size 27 oz X daily inta k e 28% = 7 . 56 oz X 1 5 % bird diet = 1 . 1 3 bird oz  

1 . 13 bir d oz X pop. of 600, 00 0 = 678 , 000 bird oz - div. by 8 oz a ver . pr e y = 84 , 750  

B urr o wi ng Owl - Pop. 60 0 , 000 - Ave r . S i ze 5. 3 oz - Da i ly Kill s 15, 000 Bird s  

S i ze 5. 3 oz X d ai l y i nta k e 28% = 1 . 5 oz X 5% bird di et = 0 . 75 bir d oz  

0.75 bir d oz X pop. of 6 00 , 000 = 45 , 000 bird oz - d i v . by 3 oz aver . prey = 15 , 000  

Eastern Screech-O w l - P op . 700 , 00 0 - A ver . S ize 6. 8 oz - D ail y Kills 159, 600 Birds  

Size 6. 8 oz X dai ly i ntake 28% = 1 . 9 oz X 30% b i rd diet = . 57 bir d oz  

. 57 bi rd oz X pop. of 7 00 , 000 = 399 , 000 bi rd oz - d i v . by 2. 5 oz p r ey = 159 , 600