(I know it's long, but I wanted to cover some ground)
If you take into account something like over 10,000 papers written on lead poisoning in raptors, less than 50 have disputed lead toxicity, and several of those were bought and paid for by organizations created to dispute the evidence...well, I dunno.
Some of the best evidence comes from the University of Minnesota Raptor Center's research. They deal with an average of something over 100 eagles annually, 75% have high levels of lead in their blood stream. These eagles begin showing up immediately after deer season opens up (bald eagles are just a well dressed vulture, as behavior goes) and continue until such time as ice out in the spring when they go back to fishing for a majority of their food.
The bloodwork regularly shows two of the four isotopes of lead. One isotope is the one found in leaded gasoline, and it is never found in the bloodwork. Second is a background isotope found naturally occurring in soils and, typically, is waters where glacial deposits left cinnabarite (a lead bearing ore), and this occurs in low levels. But the third and fourth isotopes are found in galena ores that are mined for lead smelting and is used in all kinds of industrial uses, including bullets. THAT is the one that shows up in high levels in sick birds.
Now, to narrow down possible sourcing of that lead in the bloodstream, they also began testing for copper and zinc. Why those two? Gilding metal, 95% copper, 5% zinc. That's the common jacket for dang near every modern bullet manufactured. Copper and zinc also shows up in the blood of lead poisoned raptors at the exact ratio of 95:5. This is what is known in science as a one to one correlation.
As for the vulture family, yes, they have the most amazing digestive system in the world! Turkey vultures can eat ANTHRAX INFECTED DEAD ANIMALS and digest the anthrax spores, rendering them harmless. That's pure ornery! They are also so fast in their digestion that they have to work extra hard to extract calcium before the food passes thru the digestive tract. Consequently, they are instinctually driven to swallow ANYTHING hard that they encounter while feasting on the bloated corpse of what they find. This instinct serves to drive them to eat any bone fragments they find, but also means they will grab up any bullet fragments.
Now, for bullet fragments. If you want a basic primer on what happens to a bullet after it strikes a body, follow this link:
http://www.peregrinefund.org/subsites/conference-lead/PDF/0109%20Stroud.pdfHigh speed bullets react differently than pre-smokeless powder rounds in that on impact the lead suffers more "ablation". The bullet mushrooms and exposes more surface area. This means more surface area of lead and tiny flakes of lead are freed up and remain behind in the tissue. As a sphere doubles in surface area, it triples in volume. That means the smaller the flake, the more surface area for a given mass. And it is the amount of surface area is what is the killer. A gram of lead as a solid piece is almost indigestible for a human as it will pass thru our digestive tract. A gram of lead dust is tens of thousands of times more digestible and will result in significantly higher levels of lead in the blood. When a bullet leaves behind what is now called a "lead snowstorm" of tiny fragments in the chest cavity, you leave an amount of lead behind that is extremely digestible and highly toxic.
Now, lead is known to be toxic. It is one of a very, very, very small number of elements on the periodic table that our bodies do not need in
any amount. Many elements are toxic at higher levels, but are a necessary mineral at low levels. Lead is not only unnecessary, but causes irreparable damage at any level. Not only that, but it cannot be excreted from your system once it is absorbed. Not the liver, the kidneys, the lympatic system, nor the lungs, or any system designed to excrete wastes. Once your body, or the body of any animal from the largest mammals to the smallest bacteria, absorbs an atom of lead, it is there to stay. Permanently. Forever. Amen. Chelation therapy is necessary, a chemical that is more attracted to lead than calcium receptive molecules in your body is introduced and it binds to the lead. That chemical compound is then able to be excreted from your body, but it does not happen naturally. And any damage done by the lead in the meanwhile is often irreversible, so removing the lead from the organism doesn't really fix anything.
What does lead do? It absolutely wrecks nerves and the work nerves do. The brain is affected as well as the central nervous system and the peripheral nervous system. In humans, lead poisoning leads to impaired brain function, uncoordinated muscular reaction, fumbling stumbling uncoordination.
So you aren't as nimble doing a Texas two-step with your special lady and you step on her toes more than you did when you first met. She still loves you and you both laugh and go on with your merry lives. But if you are a condor, vulture, eagle, falcon, or hawk, your very life depends on lightning fast reaction speeds. Your coordination needs to be flawless because Nature tolerates nothing but perfection. Your very ability to fly requires amazing dexterity in your wings, control over each and every flight feather, your life depends on it. Shave off a few points and suddenly it takes more work to do the deed. A few days without food and now you are out of reserves, one single day of missed meals means you no longer have the strength to fly and you are dead. Predatory birds do not carry more than a few days extra calories because flight won't allow it.
Some of the best research has been done in Wyoming on the National Elk Refuge. They conducted years of research on eagles and ravens PRIOR to doing a ammunition exchange, giving hunters copper ammo for lead. Post exchange data shows a reduction in lead levels in these scavenger species commensurate with the ratio of lead to copper hunting. Again, direct one to one correlation.
My own experience has been positive. I went with Barnes TSX copper ammo for the .243, same gun I used to shoot 3" groups at 100 yards suddenly started shooting INCHERS!!! Ha! Maybe I am not such a bad shot after all, I just needed some seriously accurate ammo. To get close to the weight of lead, they have to make a copper bullet longer and consequently, a better ballistic coefficient. Deer I shoot tend to not wander far, not with their entire lung cavity turned into squishy jelly!
If you decide to not go with lead free ammo, consider burying the gutpile so that raptors don't scavenge on the remains. That's what I am doing with the deer I shoot with the ol' flintlock.
Here's what it looks like:
http://www.bing.com/videos/search?q=youtube+minnesota+raptor+center+bald+eagle+lead+poisoning&qpvt=youtube+minnesota+raptor+center+bald+eagle+lead+poisoning&FORM=VDRE#view=detail&mid=F85E91E0AC424060CE8BF85E91E0AC424060CE8BI am available for discussion, but if you wanna troll, P.A. ain't the place. AND ARROWS AIN'T GOT ANY LEAD ANYWAY! MWAHAHAHAHA
