After going through hundreds of pages of tables, data, theories, and suppositions…I know what I believe about this issue.
I encourage anyone who wants to be sure they aren’t hurting the environment by using lead in their flies or crimping small split shot onto their leaders to go through the research themselves.
I will state plainly that I found NOTHING in ANY of the literature, studies, or text that comes even remotely close to suggesting that the use of lead in flies, or while fly fishing, is making any kind of signifcant negative impact on bird populations in the United States.
Which makes me wonder why so much of ‘switch from lead’ is aimed at us?
It would be ‘easier’ if more costly, for the bait/conventional guys to switch. They could easily use other materials for weight…not as heavy, but they can use a ‘larger’ split shot or ‘jig head’ and still get the same result…I know the fish won’t care. Many bass fishermen are going to brass or tungsten, even steel, because of the sound the harder material makes…not such an important ‘size’ issue for them
But, for us, small is often an issue. You need ‘more’ non lead wire to get the same depth (which is why we use lead, right, to sink the flies down?). On smaller flies, there may not be room for enough of the ‘non-lead’ to work. On the few flies that use lead eyes, often ‘larger’ isn’t an option…
I can’t see it being our use of the tiny fly fishing sized split shot…not all that much is used, compared to other lead sinkers, certainly not enough that even if we all switched, it would make an observable difference in bird mortality.
Why are they targeting US? Maybe because fly fishermen have always been more environmentally involved? Are we supposed to be more intelligent (I doubt that is their reasoning, since after reading all their stuff, I disagree with them…and I be teligent! 
). Or do they look at us and think we are more gullible?
Or, is this an agenda being pushed by the manufactureers of non lead fly fishing components. Look what they did with hooks a few years back…maybe because THAT worked, they think they can blitz us?
I just find all this ‘poor birdy’ stuff suspicious. I’m just skeptical enough to wonder ‘who profits’ here?
In any event, you don’t have to believe me. Look at this stuff for yourself and draw your own conclusions.
Buddy