Interesting......

[kwyeewyk]

Sounds like it's mostly related to the small size of the lead fragments from big game bullets that allow it to be easily ingested/absorbed by eagles...

Upon impact, lead rifle bullets typically shatter into several hundred fragments distributed throughout the carcass and viscera of a target animal. Estimates indicate that a single big-game bullet (e.g., 100–180 grains) impact results in an average of 235 fragments in the eviscerated carcass and 170 in the viscera (Hunt et al. 2006, 2009, Knott et al. 2010). This can substantially increase the risk of lead exposure to scavenging Golden Eagles feeding on shot carcasses and offal during the hunting season (Kelly et al. 2011, Bedrosian et al. 2012, Cruz-Martinez et al. 2012, Legagneux et al. 2014). Increased numbers of small lead fragments in carcasses result in lead being easily ingested because of their larger surface area, resulting in lead being readily absorbed into the blood stream by scavengers (Barltrop and Meek 1979).

Characterizing Golden Eagle Risk to Lead and Anticoagulant Rodenticide Exposure: A Review

Contaminant exposure is among the many threats to Golden Eagle (Aquila chrysaetos) populations throughout North America, particularly lead poisoning and anticoagulant rodenticides (AR). These threats may act in concert with others (e.g., lead poisoning and trauma associated with striking...

bioone.org

 

[Glockster]

Are we going to ban rat poison as well?
I mean if it just saves one eagle right.

 

[OntarioHunter]

True, but I assume there is still plenty around in the environment from before it was banned to provide a low level source that could be concentrated through the trophic levels, maybe I'm wrong though.

Unlike some on here, I appreciate people who are not afraid to think out loud. Shows they are at least trying to think.

Actually it appears the ban on lead shot has worked for waterfowl. Some places of high use by hunters were indeed very toxic. That's why initially the ban only went into effect in selected areas. Then it was expanded to hunting over water everywhere since it was obvious field hunting for waterfowl would almost never result in them ingesting shot (it would be plowed under every year). Then it became clear the toxicity problem expanded beyond just the waterfowl consuming the stuff. Cripples that escaped loaded with lead shot presented a very real threat to predators and scavengers, so the lead shot ban became universal for all waterfowl everywhere. Curiously, I don't think the ban on toxic shot was expanded to doves and woodcock which are also migratory. Very dumb since steel shot would be highly effective on them, much more so than heavily feathered waterfowl. I suspect these species escaped for the benefit of a relative few aficionados who want to hunt with classic guns that might get wrecked shooting steel shot. But those guys can afford bismuth or tungsten anyway.

The feds keep track of lead levels in waterfowl. Dead birds found on the refuges are, I am told, routinely checked. Periodically since the ban there have been large die-offs of waterfowl in some areas, particularly due to botulism from climate change. These incidents provide excellent opportunities to check for residual "trophic levels" effects from accumulations of pre-ban lead shot.

 

[Lyfter1013]

Cali.... lead ammo along with plastic water bottles, grocery bags, straws, coal, gas engines....

With so many people leaving California and taking the way they voted with them.. don’t be surprised. Hopefully most that leave are smart enough to change there voting ways when they make it to your state.. unfortunately I’m stuck in California until my daughter turns 18.

 

[Brandon270]

With so many people leaving California and taking the way they voted with them.. don’t be surprised. Hopefully most that leave are smart enough to change there voting ways when they make it to your state.. unfortunately I’m stuck in California until my daughter turns 18.

Not entirely true, most of those laws that were enacted we didn't even get a chance to vote on...

 

[MarvB]

Agreed @Lyfter1013 ... unfortunately my state (OR) much like many other are seemingly subject to governance by a few large populous areas. Makes it even more important to stay in the fight as active sportsmen/women trying to protect our resources. Maybe someday they will allow voting based on acreages rather than pop. density (no, I’m not holding my breath lol). I agree with following the science (as in the case of the eagle) and doing what is right when warranted; I also fear the “me to” legislators across the west that jump in line every time Cali decides to “ban something”

 

[Hunting Wife]

Some disease info for people who care...

Raptors almost always pick up lead from carcasses shot with lead bullets. Dead gophers, ground squirrels and prairie dogs shot and left laying are often the culprit. On average, the lead fragments in one dead gopher is enough to kill a hawk.

Lead does not just pass through raptors. It accumulates in the gut...we usually can see it on x-ray. It sits there and is slowly absorbed into the blood stream.

“Elevated blood lead level” is not meaningless. It refers to the blood lead relative to the normal reference range for the species and is a standard way of reporting blood chemistry parameters. It means the bird ingested enough lead to raise blood levels. The specific impacts depend not only on the level, but how long this exposure has been occurring.

Rat poison is an anti-coagulant, and has zero relation to blood lead. That would be a completely separate issue, but could certainly have been the main cause of death rather than lead for this individual. But likely the bird was exposed to both rat poison and lead via foraging on carcasses of small rodents that someone was trying to get rid of.

We see very low lead mortality in waterfowl these days, likely due to lead shot already existing in the environment now being unavailable to birds (covered by sediment, etc) and no new deposition of lead occurring.

Studies in multiple locations demonstrate higher incidence of lead-poisoning in birds coinciding with opening of rifle seasons. However I am unaware of any research pointing to population level effects to any bird species (other than California Condors and possibly Laysan Albatross) due to lead poisoning.

 

[Sytes]

Helps to have a bit more depth to understand the context within the article. Thanks HW.

 

[mtmuley]

Helps to have a bit more depth to understand the context within the article. Thanks HW.

The article gets it's point across I guess. But I do think people that read it won't bother to dig deep enough to find the information HW posted. mtmuley

 

[EKYHunter]

Some disease info for people who care...

Raptors almost always pick up lead from carcasses shot with lead bullets. Dead gophers, ground squirrels and prairie dogs shot and left laying are often the culprit. On average, the lead fragments in one dead gopher is enough to kill a hawk.

Lead does not just pass through raptors. It accumulates in the gut...we usually can see it on x-ray. It sits there and is slowly absorbed into the blood stream.

“Elevated blood lead level” is not meaningless. It refers to the blood lead relative to the normal reference range for the species and is a standard way of reporting blood chemistry parameters. It means the bird ingested enough lead to raise blood levels. The specific impacts depend not only on the level, but how long this exposure has been occurring.

Rat poison is an anti-coagulant, and has zero relation to blood lead. That would be a completely separate issue, but could certainly have been the main cause of death rather than lead for this individual. But likely the bird was exposed to both rat poison and lead via foraging on carcasses of small rodents that someone was trying to get rid of.

We see very low lead mortality in waterfowl these days, likely due to lead shot already existing in the environment now being unavailable to birds (covered by sediment, etc) and no new deposition of lead occurring.

Studies in multiple locations demonstrate higher incidence of lead-poisoning in birds coinciding with opening of rifle seasons. However I am unaware of any research pointing to population level effects to any bird species (other than California Condors and possibly Laysan Albatross) due to lead poisoning.

Nice response

 

[Hunting Wife]

The article gets it's point across I guess. But I do think people that read it won't bother to dig deep enough to find the information HW posted. mtmuley

I always cringe when I read these articles that view everything in terms of a single, named individual rather than a holistic, population or species level view. Neither conservation nor endangerment happen at the scale of the individual.

 

[mtmuley]

I always cringe when I read these articles that view everything in terms of a single, named individual rather than a holistic, population or species level view. Neither conservation nor endangerment happen at the scale of the individual.

Too much emotion. Scary how many people view wildlife that way. mtmuley

 

[Lyfter1013]

Some disease info for people who care...

Raptors almost always pick up lead from carcasses shot with lead bullets. Dead gophers, ground squirrels and prairie dogs shot and left laying are often the culprit. On average, the lead fragments in one dead gopher is enough to kill a hawk.

Lead does not just pass through raptors. It accumulates in the gut...we usually can see it on x-ray. It sits there and is slowly absorbed into the blood stream.

“Elevated blood lead level” is not meaningless. It refers to the blood lead relative to the normal reference range for the species and is a standard way of reporting blood chemistry parameters. It means the bird ingested enough lead to raise blood levels. The specific impacts depend not only on the level, but how long this exposure has been occurring.

Rat poison is an anti-coagulant, and has zero relation to blood lead. That would be a completely separate issue, but could certainly have been the main cause of death rather than lead for this individual. But likely the bird was exposed to both rat poison and lead via foraging on carcasses of small rodents that someone was trying to get rid of.

We see very low lead mortality in waterfowl these days, likely due to lead shot already existing in the environment now being unavailable to birds (covered by sediment, etc) and no new deposition of lead occurring.

Studies in multiple locations demonstrate higher incidence of lead-poisoning in birds coinciding with opening of rifle seasons. However I am unaware of any research pointing to population level effects to any bird species (other than California Condors and possibly Laysan Albatross) due to lead poisoning.

You seem to be very well informed on this and other matters such as CWD, I’m assuming you deal with this in your work not sure what you do but obviously you’re pretty knowledgeable.

I noticed in your response that you mentioned small game animals/rodents but you didn’t mention larger game or gut piles of large game animals. Do you not see larger game animals carcasses their gut piles being as big of a culprit?

 

[kwyeewyk]

On average, the lead fragments in one dead gopher is enough to kill a hawk.

I would guess at that rate it doesn't take many gut piles shot with lead to affect eagles

 

[OntarioHunter]

Some disease info for people who care...

Raptors almost always pick up lead from carcasses shot with lead bullets. Dead gophers, ground squirrels and prairie dogs shot and left laying are often the culprit. On average, the lead fragments in one dead gopher is enough to kill a hawk.

Lead does not just pass through raptors. It accumulates in the gut...we usually can see it on x-ray. It sits there and is slowly absorbed into the blood stream.

“Elevated blood lead level” is not meaningless. It refers to the blood lead relative to the normal reference range for the species and is a standard way of reporting blood chemistry parameters. It means the bird ingested enough lead to raise blood levels. The specific impacts depend not only on the level, but how long this exposure has been occurring.

Rat poison is an anti-coagulant, and has zero relation to blood lead. That would be a completely separate issue, but could certainly have been the main cause of death rather than lead for this individual. But likely the bird was exposed to both rat poison and lead via foraging on carcasses of small rodents that someone was trying to get rid of.

We see very low lead mortality in waterfowl these days, likely due to lead shot already existing in the environment now being unavailable to birds (covered by sediment, etc) and no new deposition of lead occurring.

Studies in multiple locations demonstrate higher incidence of lead-poisoning in birds coinciding with opening of rifle seasons. However I am unaware of any research pointing to population level effects to any bird species (other than California Condors and possibly Laysan Albatross) due to lead poisoning.

According to the veterinary source I found, lead bullet fragments should be expectorated orally in raptor pellets five to six hours after ingestion. If raptors naturally get rid of undigestable bone fragments in this fashion I cannot see why they would be inclined to retain bullet fragments and let them sit in their gut till absorbed as you maintain. You might see bullet fragments with a post mortem x-ray in the storage gut ahead of the stomach but you have no way of knowing if the stuff has been in the raptor long enough to cause significant poisoning ... which I would think would be longer than 5-6 hrs. Of course, multiple insignificant exposures would eventually add up to significant lethal lead levels. Waterfowl, on the other hand, would retain any bullet fragments or shotgun pellets in their gizzard where that material would essentially be treated like gravel and used as an abrasive to grind food. Lead fragments would not be regurgitated, instead they would ultimately be ground to soup and easily cross cell walls in the digestive tract. I'm guessing near 100% absorption.

 

[Hunting Wife]

You seem to be very well informed on this and other matters such as CWD, I’m assuming you deal with this in your work not sure what you do but obviously you’re pretty knowledgeable.

I noticed in your response that you mentioned small game animals/rodents but you didn’t mention larger game or gut piles of large game animals. Do you not see larger game animals carcasses their gut piles being as big of a culprit?

Given the specific individual in the article and the facts of that one case, its likely that rodents are the culprit here.

On a landscape level, yes gut piles can be point sources for lead, no question. Does anyone have data to quantify exposure via the two or determine which is worse? Not that I’m aware of. My gut tells me which source is the biggest culprit is highly location-dependent, and I also think there is probably some variability in which species are likely to ingest lead from dead rodents vs gut piles. So which is “worse”? I have no idea, and I don’t think anyone else does either.

Are there things we as hunters could do to minimize lead in the environment? Certainly. Is one blanket strategy going to work everywhere? Not likely.

I would guess at that rate it doesn't take many gut piles shot with lead to affect eagles

It’s not an apples to apples comparison. You often have higher weight retention in a larger bullet, and fragments dispersed in a larger carcass, a significant portion of which is removed from the landscape. So hard to make a straight comparison between gut piles and rodent carcasses.

According to the veterinary source I found, lead bullet fragments should be expectorated orally in raptor pellets five to six hours after ingestion. If raptors naturally get rid of undigestable bone fragments in this fashion I cannot see why they would be inclined to retain bullet fragments and let them sit in their gut till absorbed as you maintain. You might see bullet fragments with a post mortem x-ray in the storage gut ahead of the stomach but you have no way of knowing if the stuff has been in the raptor long enough to cause significant poisoning ... which I would think would be longer than 5-6 hrs. Of course, multiple insignificant exposures would eventually add up to significant lethal lead levels. Waterfowl, on the other hand, would retain any bullet fragments or shotgun pellets in their gizzard where that material would essentially be treated like gravel and used as an abrasive to grind food. Lead fragments would not be regurgitated, instead they would ultimately be ground to soup and easily cross cell walls in the digestive tract. I'm guessing near 100% absorption.

They can regurgitate lead, but certainly not always and particularly so for small individual fragments. Plus raptor digestion lends itself to rapid uptake of lead into the bloodstream. When I pick up an eagle that’s been sitting in someone’s yard immobile for 2 days, it takes me 24-48 hours to get it to the vet, and it shows lead in the GI on x-ray and elevated blood lead levels, that lead has most certainly been there longer than 5-6 hours, no matter what you read.

 

[theat]

I've found and caught two eagles that were suffering from lead poisoning. Both birds could not fly or really walk. The eagle in these pictures was sitting on a log in the middle of a small bay a few miles from my house. I was walking the shore with my dog and it jumped into the river and managed to use its wings to swim to shore. It tried to run away from me, but could barely walk with its talons clenched. I found these birds at the end of rifle hunting season and the second just after the season ended. Thankfully, I was able to get them both to a raptor rehabilitator and with a couple weeks of EDTA treatment for lead poisoning, they both recovered and were able to be released near where I found them. There is very little, if any rodent hunting that takes place in this area. I am pretty confident that the lead poisoning came from deer or elk carcases.

 

[SAJ-99]

Waterfowl were/are more susceptible than raptors because they have a gizzard to store lead pellets as grinding gravel whereas raptors, like mammal predators, should pass it through (or rather back out) of their system relatively quickly.

Raptors have a ventriculus. Causes the same problem.

 

[SAJ-99]

Too much emotion. Scary how many people view wildlife that way. mtmuley

But that is how you raise the emotion in people (for better or worse). Talking about averages in a population is often ignored. Talk about a specific individual and it is more emotional.

 

[mtmuley]

But that is how you raise the emotion in people (for better or worse). Talking about averages in a population is often ignored. Talk about a specific individual and it is more emotional.

Understood. With wolves in a big way. Now birds in the Bitterroot. mtmuley