Preventing Bird Deaths from Lead Poisoning
In her second guest post, wildlife vet Helene Van Doninck shares troubling stories about human-wildlife interactions. Lead poisoning is the topic of this entry – Helene tells us how you can prevent unnecessary bird deaths that result from this toxic substance.
As a wildlife veterinarian and rehabilitator, I get a first hand glimpse into what happens when wild birds and humans interact. While many of these encounters are positive, I often see the results when the outcome is negative for the bird. More than ninety percent of the admissions to our rehabilitation centre are a direct result of interaction with humans or our structures.
Each year we analyze the reasons birds and other wildlife are brought to us seeking medical aid. The top reasons for admission include birds that are: hit by a vehicle, victims of cat predation, poisoned (lead poisoning in particular), injured from striking a window, orphaned, oiled, and shot.
We spend a considerable amount of time trying to provide education that will help to decrease the number of animals that are victims of human interaction. People who bring us birds often ask how they can help. For several of the causative reasons listed above, the solution is obvious.
Thousands of wild animals are struck by vehicles every year and simply driving slower and being more aware during dawn and dusk-periods of increased activity may help decrease collisions. Birds of prey and scavenging species are often struck when they opportunistically consume other vehicle collision victims. To help prevent this (not for the faint of heart), I personally carry a shovel in my vehicle and if it is safe to do so, will move dead animals to the ditch or well off the road to prevent another wildlife death. In 2010, we admitted 2 bald eagles that had been struck while scavenging. Both died of their injuries despite medical care.
In recent years we have seen an increase in bird deaths due to lead poisoning. Sadly, these deaths are easily preventable. It has been known for years that lead is toxic, yet it is still used to make hunting and fishing gear and in the manufacturing of other items. Lead shot was banned in waterfowl hunting years ago, but it is still legal to use for hunting other species.
The most common species to get lead poisoning are bald eagles and common loons. Eagles can ingest lead shot (just one ingested pellet or sinker can kill) when scavenging bodies or remnants of bodies left behind by hunters. Some animals are also wounded but not killed and then scavenged by eagles. Loons can ingest lead sinkers or lures left behind on lake beds – lines are often cut when the sinker or gear gets entangled under the water. It is thought that loons either see the reflective lure and go after it, assuming it is a fish, or accidentally ingest the sinker when picking up bits of rock on the lake bed, which is necessary for proper digestion.
Lead poisoned loons are weakened and unable to fly or dive. They will stop eating, have seizures, and get diarrhoea and paralysis of neck muscles. Lead poisoned bald eagles are usually found on the ground unable to fly in a weakened and thin state. They often have a drooped head and wings and are unable to respond to threats by other predators. The poisoning is fatal without treatment and can be fatal even with treatment if the lead levels are high enough or the animal goes too long without receiving care.
Anytime we receive a bald eagle that is unable to fly, but with no signs of injury, lead is my first suspicion. The bird is x-rayed to look for lead, though absence of lead on an x-ray still warrants further investigation in a symptomatic bird. If the eagle ingested the pellet more than two weeks ago, the powerful muscles and presence of other grit in the digestive tract will grind the lead down and release it into the blood stream, making it undetectable by x-rays. In these kinds of cases, a blood sample is sent to confirm the diagnosis and then we start the long process of chelation therapy to try and remove the lead from the victim. This means injections for five to ten days, follow-up blood work, intravenous fluids and tube-feeding to support an animal too sick and weak to ingest food or water. These birds require high maintenance, supportive care until they can stand and eat on their own – they will be in recovery for weeks to months if they survive.
One typical case we received involved a loon seen swimming in circles and unable to dive. The people who noted this were unable to capture it and monitored the loon for one day. The next day the bird, a mature male, was found on land in a weakened state. It was brought to us and died within hours despite medical therapy – it was simply too far gone. We confirmed a diagnosis of lead poisoning with x-rays, blood tests and an autopsy. One lead sinker killed this bird. The person who found the bird called me several days later to tell me that its mate swam back and forth near where the poisoned loon beached, making distress vocalizations for days after its mate died an unnecessary death.
How can you prevent this?
The answer is simple. Avoid using products containing lead, and in particular, do not use lead shot or fishing gear. Alternatives such as steel and bismuth do exist and are available. Ask for and demand these alternatives in tackle, hunting and bait shops. You may just save a life.